UBC Theses and Dissertations

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UBC Theses and Dissertations

Chelate compounds as seed protectant fungicides and the evolution of toxic gases from chelate fungicides… Lopatecki, Leighton Eugene 1951

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CHELATE COMPOUNDS AS SEED PROTECTANT FUNGICIDES AND THE EVOLUTION OF TOXIC GASES FROM CHELATE FUNGICIDES RELATED TO DITHIOCARBAMIC ACID A THESIS SUBMITTED I N PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE I N AGRICULTURE by L e i g h t o n Eugene L o p a t e c k i i- a, .£u-ys-«__ L^ux^z Lo^h^c-kt i n t h e DEPJETMENT OF AGRONOMY WE ACCEPT THIS THESIS AS CONFORMING TO THE STANDARD REQUIRED FROM CANDIDATES FOR THE DEGREE OF MASTER OF SCIENCE I N AGRICULTURE MEMBERS OF THE DEPARTMENT OF AGRONOMY THE UNIVERSITY OF B R I T I S H COLUMBIA A P R I L , 1951. ABSTRACT A n a t t e m p t was made t o c r e a t e e f f e c t i v e f u n g i c i d e s b y c o m b i n i n g f u n g i s t a t i c c h e l a t e s w i t h m e r c u r y and o t h e r m e t a l s . Two c h e l a t e s , c u p f e r r o n a n d p h e n y l - t h i o d a n t o i c a c i d , w e r e f o u n d h i g h l y f u n g i s t a t i c , a n d t h e e f f e c t i v e n e s s o f t h e i r m e r c u r y com-p l e x e s as s e e d p r o t e c t a n t s was s i m i l a r t o t h a t o f t h e s t a n d a r d f u n g i c i d e A r a s a n . The m e r c u r y c o m p l e x o f c u p f e r r o n was f o u n d r e l a t i v e l y u n s t a b l e , a n d m e r c u r y was e a s i l y d i s p l a c e d b y m e t a l s f o r m i n g more s t a b l e c o m p l e x e s . On t h e o t h e r h a n d , m e r c u r y c o u l d n o t be d i s p l a c e d f r o m t h e p h e n y l - t h i o h y d a n t o i c a c i d c o m p l e x , a n d f u n g i s t a t i c a l l y , t h i s compound a p p e a r e d t o f u n c t i o n a s a n u n d i s -s o c i a t e d m o l e c u l e . S l o p e s o f d o s a g e - r e s p o n s e c u r v e s o f b o t h c h e l a t e s were d e c r e a s e d b y t h e i n c l u s i o n o f m e r c u r y , and t h e e f f i c i e n c y o f b o t h compounds i n c r e a s e d a s r e s p i r a t i o n i n h i b i t o r s . H o w e v e r , b o t h c h e l a t e s a n d t h e i r m e r c u r y c o m p l e x e s w e r e more e f f e c t i v e g r o w t h i n h i b i t o r s t h a n r e s p i r a t i o n i n h i b i t o r s , and t h e i r f u n g i s t a t i c v a l u e s c o u l d n o t be e s t i m a t e d b y r e s p i r a t i o n m e t h o d s . E v o l u t i o n o f t o x i c g a s e s f r o m d i t h i o c a r b a m a t e c h e l a t e f u n g i c i d e d u r i n g d e c o m p o s i t i o n was measured i n t h e W a r b u r g I I m a n o m e t e r . I t was c o n c l u d e d t h a t t h e d i a l k y l s e r i e s o f d i t h i o c a r b a m a t e s decomposed i n t h e p r e s e n c e o f s l i g h t l y a c i d b u f f e r s t o p r o d u c e c a r b o n d i s u l p h i d e a n d a d i a l k y l - a m i n e , D i t h a n e , o n t h e o t h e r h a n d , decomposed w i t h e v o l u t i o n o f h y d r o g e n s u l p h i d e a n d c a r b o n d i s u l p h i d e , a n d , i t was a s s u m e d , w i t h a r e s i d u e o f e t h y l e n e t h i o u r e a . ACKNOWLEDGMENTS G r a t e f u l a c k n o w l e d g m e n t s a r e d u e t o D r . W . N e w t o n , o f t h e D o m i n i o n L a b o r a t o r y o f P l a n t P a t h o l o g y , S a a n i c h t o n , f o r many h e l p f u l d i s c u s s i o n s a n d s u g g e s t i o n s i n c o n n e c t i o n w i t h t h i s w o r k . G r a t e f u l a c k n o w l e d g m e n t s a r e due a l s o t o D r . J . C . W o o d w a r d , D o m i n i o n A g r i c u l t u r a l C h e m i s t , f o r p e r -m i s s i o n t o s u b m i t t h i s t h e s i s b a s e d o n w o r k c a r r i e d o u t a t S a a n i c h t o n , w h i l e t h e a u t h o r h e l d t h e p o s i t i o n o f A g r i c u l t u r a l R e s e a r c h O f f i c e r i n t h e D i v i s i o n o f C h e m i s t r y o f S c i e n c e S e r v i c e . TABLE OF CONTENTS Page A b s t r a c t I n t r o d u c t i o n L i t e r a t u r e R e v i e w s : Seed P r o t e c t a n t F u n g i c i d e s ' . "1 C h e l a t e Compounds a n d C h e l a t e F u n g i c i d e s . . . . 3 L a b o r a t o r y A s s a y o f F u n g i c i d e s 12 E x p e r i m e n t a l P a r t I The P r e p a r a t i o n a n d E v a l u a t i o n o f C h e l a t e s a s Seed P r o t e c t i o n F u n g i c i d e s , . . . .14 P r e p a r a t i o n o f M e t a l Complexes o f C u p f e r r o n and P h y n l - t h i o h y d a n t o i c a c i d 19 E v a l u a t i o n o f M e t a l C o m p l e x e s b y G r e e n h o u s e E x p e r i m e n t s 20 Mode o f A c t i o n o f M e r c u r y Complexes 24 P a r t I I The E v o l u t i o n o f T o x i c Gases f r o m C h e l a t e F u n g i c i d e s R e l a t e d t o D i t h i o - c a r b a m i c A c i d . . . . 3 5 S o d i u m D i e t h y l - d i t h i o c a r b a m a t e 36 M e t a l Complexes o f D i m e t h y l - d i t h i o c a r b a m a t e . .40 D i t h a n e 43 D i s c u s s i o n .48 B i b l i o g r a p h y INTRODUCTION To a n y s t u d y i n v o l v i n g t h e c o n t r o l o f d i s e a s e o r g a n i s m s b y c h e m i c a l s , E h r l i c h ' s (25) c o n c e p t o f " d o s i s c u r a t i v a " and " d o s i s t o l e r a t a " , i s o f f u n d a m e n t a l i m p o r t a n c e . I n o t h e r w o r d s , t h e s e s t u d i e s a r e c o n c e r n e d b a s i c a l l y w i t h t h e r e l a t i o n s h i p b e t w e e n t h e d o s e t o x i c t o t h e p a r a s i t e , t o t h e d o s e t o l e r a t e d b y t h e h o s t . I n t h e e a r l y h i s t o r y o f p l a n t p a t h o l o g y , t h e i n o r g a n i c compounds u s e d f o r c o n t r o l o f d i s e a s e s w e r e g e n e r a l l y t o x i c t o b o t h t h e p a r a s i t e a n d t h e h o s t . Thus e f f e c t i v e d i s e a s e c o n t r o l was o b t a i n e d o n l y w i t h some c o r r e s p o n d i n g damage t o t h e p l a n t . F o l l o i v i n g t h e i n t r o d u c t i o n o f t h e d i t h i o c a r b a m a t e f u n g i c i d e s b y T i s d a l e and W i l l i a m s (52) i n 1944, t h e r e a p p e a r e d two v e r y i m p o r t a n t f e a t u r e s f a v o r i n g o r g a n i c o v e r i n o r g a n i c com-pounds f o r p l a n t d i s e a s e c o n t r o l . The f i r s t f e a t u r e was t h a t many o r g a n i c compounds t e n d t o be f u n g i s t a t i c , r a t h e r t h a n f u n g i c i d a l ; t h a t i s , t h e y i n h i b i t c e l l g r o w t h , w i t h o u t a t t h e same t i m e , k i l l i n g t h e c e l l s . S e c o n d l y , t h e g r o w t h i n h i b i t i n g a c t i o n o f o r g a n i c compounds t e n d s t o be more s p e c i f i c t h a n t h e a c t i o n o f i n o r g a n i c s . B o t h t h e s e f e a t u r e s a s s i s t i n s e l e c t i n g o r g a n i c compounds w h i c h h a v e a b r o a d e r s e p a r a t i o n b e t w e e n t h e " d o s i s c u r a t i v a " and t h e tl " d o s i s t o l e r a t a " . The p r e s e n t p a p e r c o n s i s t s o f t h e f o l l o w i n g two p h a s e s o f t h e p r o b l e m o f p l a n t d i s e a s e c o n t r o l b y o r g a n i c f u n g i c i d e s . 1 The p r o d u c t i o n o f a c t i v e f u n g i s t a t i c a g e n t s f r o m compounds r e l a t e d t o t h e d i t h i o c a r b a m a t e s t h r o u g h common c h e l a t i n g p r o p e r -t i e s . 2 A s t u d y o f t h e c o n d i t i o n s p r o d u c i n g d e c o m p o s i t i o n o f d i t h i o c a r b a m a t e s , and t h e i d e n t i f i c a t i o n o f t h e t o x i c ga se s g i v e n o f f f r o m t h e s e c o m p o u n d s . LITERATURE REVIEWS S e e d P r o t e c t a n t F u n g i c i d e s Due t o t h e u b i q u i t o u s n a t u r e o f s o i l - b o r n p l a n t p a t h o -g e n i c f u n g i i n a g r i c u l t u r a l a r e a s , McNew (38) ha s p o i n t e d o u t t h a t i t r e q u i r e s u n f a v o u r a b l e w e a t h e r c o n d i t i o n s o n l y t o p r o d u c e i n j u r y . D a m p i n g - o f f o f s e e d l i n g s b y s o i l i n h a b i t i n g f u n g i i s c o n s i d e r e d b y L e u k e l ( 2 9 ) t o b e t h e mos t s e r i o u s p r o b l e m e n c o u n t e r e d i n o b t a i n i n g good s t a n d s o f v e g e t a b l e c r o p s , and one o f t h e m a j o r t y p e s o f damage o f a l l c r o p s . A l t h o u g h many f u n g i may b e i n v o l v e d i n t h e d a m p i n g - o f f o f s e e d l i n g s , H e a l d (17) c o n s i d e r s P y t h i u m d e b a r y a n u m t o be o f m a j o r i m p o r t a n c e . O f t h e o t h e r m o l d s i n v o l v e d , H e a l d (17) i n c l u d e s P y t h u m u l t i m u m , a n d members o f t h e genus P h y t o p h t h o r a . Seed t r e a t m e n t may be d o n e f o r one o f t w o p u r p o s e s : t o p r o t e c t t h e seed f r o m s o i l - b o r n o r g a n i s m s , o r t o k i l l d i s e a s e o r g a n -i s m s t h a t o v e r - w i n t e r i n , o r o n , t h e s e e d c o a t . Compounds o f t h e f i r s t c l a s s a r e known a s " s e e d p r o t e c t a n t s " , a n d o f t h e s e c o n d , " s e e d d i s i n f e c t a n t s " . Of t h e s e two t y p e s o f compounds , s e e d p r o -t e c t a n t s a r e t h e m o s t u n i v e r s a l l y r e q u i r e d . The c o n t r o l o f d a m p i n g - o f f b y s e e d t r e a t m e n t has b e e n d i s c u s s e d b y Kadow a n d A n d e r s o n ( 2 8 ) a n d b y H o r s f a l l (24), w h i l e T a y l o r a n d R u p e r t (50) h a v e g i v e n a r e v i e w o f t h e h i s t o r y o f v e g e t a b l e s e e d p r o t e c t a n t s . M o r e r e c e n t d e v e l o p m e n t s o f c o n t r o l 2 m e a s u r e s a r e g i v e n i n a r e v i e w b y L e u k e l (29). A c c o r d i n g t o M a r t i n (30), e a r l y methods o f s e e d t r e a t m e n t c o n s i s t e d i n s o a k i n g seeds i n s o l u t i o n s o f f u n g i c i d e s , p r i n c i p a l l y c o p p e r s u l p h a t e a n d f o r m a l d e h y d e . L e u k e l (29) p o i n t s o u t t h a t f o l l o w i n g t h e d i s c o v e r y o f c o p p e r c a r b o n a t e d u s t a s a b u n t i c i d e , t h e r e was a g r a d u a l change t o d u s t f u n g i c i d e s . T h i s change was a t t r i b u t e d t o t h e ea se o f h a n d l i n g o f d u s t f u n g i c i d e s made p o s s i b l e b y t h e d e v e l o p m e n t o f v a r i o u s home-made m i x e r s a n d t r e a t e r s . The i n t r o d u c t i o n o f r e d a n d y e l l o w c u p r o u s o x i d e s b y H o r s f a l l (22) (19), a n d o f z i n c o x i d e (23) f u r t h e r s t i m u l a t e d i n t e r e s t i n t h e u s e o f d u s t s a s s e e d p r o t e c t a n t s . O r g a n i c s eed p r o t e c t a n t s i n t h e f o r m o f d u s t s d a t e f r o m t h e i n t r o d u c t i o n o f t e t r a c h l o r o - p a r a - b e n z o - q u i n o n e , o r S p e r g o n , b y Cunningham a n d S h a r w e l l (10) i n 1940. S p e r g o n was f o l l o w e d q u i c k l y b y t e t r a m e t h y l - t h i u r a m d i s u l p h i d e , o r A r a s a n , a n d f e r r i c d i m e t h y l -d i t h i o c a r b a m a t e , known a s F e r m a t e . These compounds r e c e i v e d f a v o r -a b l e comments f r o m McNew (39), T a y l o r , R u p e r t a n d L e a c h (51), a n d many o t h e r s . I n t h e f i n a l a n a l y s i s , t h e judgment o f a n y f u n g i c i d e i s a n e c o n o m i c o n e . M c C a l l a n (35) h a s d i s c u s s e d t h e f a v o u r a b l e p o s i t i o n h e l d b y s e e d p r o t e c t a n t s i n t h i s r e s p e c t . B e c a u s e o f t h e c o s t s o f h a n d l i n g a n d t h e l a r g e amounts o f m a t e r i a l r e q u i r e d , f i e l d s p r a y s a n d d u s t s a r e l i m i t e d t o t h e h i g h v a l u e p e r a c r e c r o p s . On t h e o t h e r h a n d , s e e d p r o t e c t a n t s a r e b e i n g u s e d p r o f i t a b l y o n t h e l o w v a l u e p e r a c r e g r a i n c r o p s . The c o r o l l a r y i s a l s o t r u e : t h a t e x p e n s i v e m a t e r i a l s i n t h e f o r m o f o r g a n i c s o r m e r c u r i a l s , r e g a r d -l e s s o f e f f e c t i v e n e s s , c a n f i n d economic u s e o n l y i n s e e d t r e a t -m e n t . C h e l a t e Compounds a n d C h e l a t e F u n g i c i d e s 1 C h a r a c t e r i s t i c s o f C h e l a t i n g A g e n t s The f i r s t u s e o f a c h e l a t e a s a f u n g i c i d e was i n 1914, when 8 - h y d r o x y - q u i n o l i n e , o r o x i n e , was t r i e d b y H i l t n e r (20) a s a s e e d p r o t e c t a n t . The same compound, u n d e r t h e p r o p r i e t a r y name o f C h i n o s o l , h a d b e e n p l a c e d o n t h e m a r k e t i n Germany a s a b a c t e r i o c i d e , t w e n t y y e a r s e a r l i e r . 5" O H S i A s c a n b e s e e n f r o m t h e a c c o m p a n y i n g f o r m u l a , o x i n e c o n s i s t s o f a t o x i c p h e n o l i c r i n g , a t t a c h e d t o a n o n t o x i c p y r i d i n e r i n g (25). T h i s com-pound a p p e a r e d f o r many y e a r s t o p o s s e s s a number o f t o x i c o l o g i c a l r e a c t i o n s w h i c h w e r e s t r u c t u r a l l y a n o m o l o u s . T h e s e r e a c t i o n s w e r e : ( a ) The compound i s f u n g i s t a t i c , n o t f u n g i c i d a l , as w o u l d be e x p e c t e d b y t h e p r e s e n c e o f t h e t o x i c p h e n o l i c r i n g . ( b ) O n l y when t h e h y d r o x y l g r o u p i s i n t h e e i g h t h p o s i t i o n i s t h e compound f u n g i s t a t i c . (c) The compound i s more e f f e c t i v e against Gram p o s i t i v e than against Gram negative organisms. » These os t e n s i b l y anomalous reactions were explained by Albert (1) and by Zentmyer (57), i n 1944 when they co-ordinated a n t i - b a c t e r i a l and a n t i - f u n g a l a c t i v i t y o f oxine with c h e l a t i n g a b i l i t y . The term "chelate", derived from "chela", the great claw o f the c r u s t a t i o n s , was introduced by Morgan and Drew i n 1920 (34). Chelate i s a d e s c r i p t i v e term f o r the c a l i p e r - l i k e groups, which, functioning as two assoc-H H : C : W H i a t e d u n i t s , f a s t e n onto a c e n t r a l m e t a l l i c atom to form h e t r o c y c l i c r i n g s . For example, oxine i s able to bind zinc according to the accompanying formula. Here zinc i s l i n k e d simultaneously to pheno-l i c oxygen by normal valencies, and by nitrogen through co-ordin-ated covalent bonds. The o r i g i n of co-ordinated covalent bonds may be b r i e f l y stated as f o l l o w s : i n the normal covalent bond of organic compounds, the single bond consists o f a p a i r 5 o f s h a r e d e l e c t r o n s , a s i l l u s t r a t e d b e l o w f o r m e t h a n e . Thus one e l e c t r o n comes f r o m c a r b o n , a n d t h e o t h e r f r o m h y d r o g e n . The s h a r e d e l e c t r o n s , c o n s t i t u i n g a s i n g l e b o n d , a r e c o n v e n t i o n a l l y r e p r e s e n t e d b y a s i n g l e l i n e . I n some c o n d i t i o n s , b o t h e l e c t r o n s may b e d o n a t e d b y a s i n g l e a t o m . R e f e r r i n g t o o x i n e , t h e v a l e n c e o f n i t r o g e n i n t h e p y r i d i n e r i n g i s t h r e e , w h i l e n i t r o g e n h a s a p o t e n t i a l v a l e n c e o f f i v e . Z i n c on t h e o t h e r h a n d , ha s two v a l e n c e e l e c t r o n s o n l y , and t h e s e a r e a l r e a d y t a k e n up b y o x y g e n . A c c o r d i n g l y , b o t h t h e e l e c t r o n s f o r m i n g e a c h s i n g l e b o n d b e t w e e n n i t r o g e n a n d z i n c must be d o n a t e d b y t h e n i t r o g e n a t o m . The d i r e c t i o n o f e l e c t r o n s d o n a t i o n i s i n d i c a t e d c o n v e n t i o n a l l y b y t h e u s e o f a n a r r o w . A s m e n t i o n e d p r e v i o u s l y , f u n g i s t a t i c a c t i v i t y o f o x i n e i s l i m i t e d t o t h e a n o l o g u e w i t h t h e h y d r o x y l g r o u p i n t h e e i g h t h p o s i t i o n . C h e l a t i n g a c t i v i t y i s s i m i l a r l y l i m i t e d , s i n c e r i n g s f o r m e d o f more t h a n f i v e e l e m e n t s i n t h i s t y p e o f s t r u c t u r e a r e u n s t a b l e . S u c h i n s t a b i l i t y i s e x p l a i n e d l o g i c a l l y b y t h e s t r a i n t h e o r y . The n o r m a l , ( a n d h e n c e t h e most s t a b l e ) a n g l e b e t w e e n v a l e n c i e s o f t h e c a r b o n a t o m d i r e c t e d a t t h e v e r t i c i e s o f a r e g u l a r t e t r a h e d r o n a r e 109°, w h i l e t h e a n g l e b e t w e e n t h e s i d e s o f a r e g u l a r p e n t a g o n a r e a l m o s t i d e n t i c a l a t 110° . The c o r r e s p o n d i n g a n g l e s o f a h e x a g o n a r e , h o w e v e r , c o n s i d e r -a b l y l a r g e r a t 120°. E l i m i n a t i o n o f s t r a i n i n s i x membered c h e l a t e r i n g s fo rmed f r o m o x i n e b y z i g z a g g i n g i n two p l a n e s , s u c h a s Desha (11) d e s c r i b e s f o r t h e b e n z e n e r i n g i s a p p a r e n t l y n o t p o s s i b l e . Thus s u c h s i x membered r i n g s f o r m e d f r o m 7 h y d r o x y - q u i n o l i n e a r e u n s t a b l e , 6 and A l b e r t (3) r e p o r t s c h e l a t i n g a b i l i t y as w e l l a s f u n g i s t a t i c a b i l i t y i s o f a l o w o r d e r . I n t h e o r i g i n a l o x i n e m o l e c u l e , o n l y two h y d r o p h i l l i c g r o u p s a r e p r e s e n t , - OH a n d - N r . F o l l o w i n g c o m p l e x f o r m a t i o n , b o t h t h e s e g r o u p s a r e m a s k e d , w i t h t h e r e s u l t t h a t t h e c o m p l e x i s e x c e e d -i n g l y i n s o l u b l e i n w a t e r . A c c o r d i n g l y , when o x i n e i s added t o a f u n g u s c u l t u r e , t r a c e m e t a l s a r e p r e c i p i t a t e d a n d g r o w t h c e a s e s , a s Z e n t m y e r (58) h a s s h o w n , a s a r e s u l t o f t r a c e m e t a l d e f i c i e n c y . The example o f m e t a l - c o m p l e x f o r m a t i o n o f o x i n e i s i n many r e s p e c t s t y p i c a l o f t h e a c t i o n o f c h e l a t e s g e n e r a l l y . I n f o r m a t i o n o n t h e a c t i o n o f o t h e r c h e l a t i n g a g e n t s i s t o b e f o u n d i n t h e monographs b y W e l c h e r (54) a n d Zoe a n d S a r v e r (59). Some a d d i t i o n a l f e a t u r e s o f c h e l a t e a c t i o n p e r t i n e n t t o t h e f o l l o w i n g d i s c u s s i o n s , a r e g i v e n f r o m W e l c h e r . O x i n e i s a n example o f a c h e l a t e w h i c h f o r m s n o n i o n i z e a b l e c o m p l e x e s , r e f e r r e d t o as i n n e r c o m p l e x s a l t s . I n n e r c o m p l e x s a l t s r e a c t more a s p u r e o r g a n i c s t h a n as i n o r g a n i c compounds , and t h e m e t a l c o n t a i n e d i n s u c h c o m p l e x e s c a n n o t be d e t e c t e d b y o r d i n a r y means , s u c h a s p r e c i p i t a t i o n w i t h h y d r o g e n s u l p h i d e . T h e s e c o m p l e x e s , t h o u g h u s u a l l y v e r y i n s o l u b l e i n w a t e r , a r e s o l u b l e i n o r g a n i c l i q u i d s . C h e l a t i n g a g e n t s g e n e r a l l y combine w i t h a c o n s i d e r a b l e num-b e r o f m e t a l s , and combine s p e c i f i c a l l y o n l y b e t w e e n c e r t a i n n a r r o w pH l i m i t s . The s t a b i l i t y c o n s t a n t s o f d i f f e r e n t m e t a l c o m p l e x e s o f a c h e l a t i n g a g e n t v a r y c o n s i d e r a b l y . M e l l o r and M a l e y (32) s u g g e s t e d t h a t t h e o r d e r o f s t a b i l i t y c o n s t a n t s o f m e t a l - c h e l a t e c o m p l e x e s i s p r o b a b l y s i m i l a r r e g a r d l e s s o f c h e l a t i n g a g e n t . F u r t h e r e v i d e n c e s u p p o r t i n g t h i s v i e w i s p r e s e n t e d i n t h e e x p e r i m e n t a l p o r t i o n o f t h i s t h e s i s . M o s t i m p o r t a n t o f t h e c h e l a t e s u s e d as f u n g i c i d e s a r e t h e d i t h i o c a r b a m a t e s . I n f a c t , M c C a l l a n (36) c o n s i d e r s t h e d i t h i o c a r b a -mate s t h e mos t e f f e c t i v e o r g a n i c f u n g i c i d e s so f a r d i s c o v e r e d . The i n t r o d u c t i o n o f t h e s e compounds d a t e s f r o m 1934, when T i s d a l e a n d W i l l i a m s (52) o b t a i n e d a p a t e n t o n t h e i r f u n g i c i d a l u s e . The f u n g i -c i d a l a c t i o n o f t h e s e compounds ha s b e e n s t u d i e d i n d e t a i l b y G o l d s w o r t h y , G r e e n and S m i t h , (16), a n d Dimond e t a l (12), w h i l e t h e p r e s e n t s t a t u s o f t h e d i t h i o c a r b a m a t e s a s f u n g i c i d e s h a s b e e n r e v i e w e d b y H e u b e r g e r ( I S ) . The d i t h i o c a r b a m a t e f u n g i c i d e s a r e r e l a t e d t o t h e c h e l a t e s o d i u m d i m e t h y l - d i t h i o c a r b a m a t e , w h i c h i n t u r n i s r e l a t e d t o c a r b o n i c a c i d as i l l u s t r a t e d b e l o w . c ^ c o=c S ~ £ 8 S o d i u m d i m e t h y l - d i t h i o c a r b a m a t e i s a t y p i c a l c h e l a t i n g a g e n t , f o r m i n g c o - o r d i n a t i o n compounds w i t h m e t a l s o f t h e f o l l o w i n g t y p e : A s H o r s f a l l (25) ha s shown, s o d i u m d i m e t h y l - d i t h i o c a r b a m a t e i s a l s o a v e r y p o w e r f u l f u n g i s t a t i c a g e n t . N e v e r t h e l e s s , t h e compound c a n n o t b e u s e d d i r e c t l y a s a p r o t e c t i v e f u n g i c i d e b e c a u s e o f h i g h s o l u b i l i t y . I n s o l u b l e d e r i v a t i v e s h a v e , a s a r e s u l t , b e e n p r e p a r e d b y t h e f o l l o w i n g t h r e e m e t h o d s : 1 B y c o m b i n i n g two m o l e c u l e s o f t h e c h e l a t e t h r o u g h s u l p h u r t o p r o d u c e t e t r a m e t h y l - t h i u r a m - d i s u l p h i d e , now known a s A r a s a n . 2 B y c o m b i n i n g two m o l e c u l e s t h r o u g h t h e m e t h y l g r o u p s t o p r o d u c e d i s o d i u m - e t h y l e n e - b i s d i t h i o c a r b a m a t e , o r D i t h a n e . 3 B y p r e p a r i n g i n s o l u b l e c h e l a t e c o m p l e x e s f r o m m e t a l s a l t s a s p r e v i o u s l y i l l u s t r a t e d . The b e s t known o f t h e s e , a r e t h e i r o n a n d z i n c c o m p l e x e s , F e r m a t e a n d Z e r l a t e . R e f e r e n c e t o t h e f o r m u l a e j u s t g i v e n shows t h a t w h i l e - D i t h a n e r e t a i n s i t s c h e l a t i n g a b i l i t y , A r a s a n d o e s n o t . T h u s , b y 9 r e p l a c i n g s o d i u m i n D i t h a n e , e v e n more i n s o l u b l e m a t e r i a l s a r e p r o -d u c e d . The b e s t known o f t h e s e compounds i s t h e z i n c c o m p l e x P a r z a t e . The c h e l a t i n g a b i l i t y o f L i t h a n e i s a l s o o f i m p o r t a n c e t o t h e f u n g i s -t a t i c a c t i o n o f t h i s compound, a s w i l l be d i s c u s s e d l a t e r . V e r y l i t t l e h a s b e e n r e p o r t e d o n t h e v a l u e o f o t h e r c h e l a t e s a s f u n g i c i d e s . H o r s f a l l a n d Z e n t m y e r (26) h a v e shown h o w e v e r , t h a t t h e c h e l a t e s c u p r o n , c u p f e r r o n , and s a l a c y l a l d o x i m e a r e a c t i v e f u n g i -s t a t i c a g e n t s . H o r s f a l l (25) a t t e m p t e d t o c o m b i n e t h e t o x i c i t y o f c o p p e r w i t h t h e t o x i c i t y o f s a l a c y l a l d o x i m e i n t h e f o r m o f t h e c o p p e r c o m p l e x , b u t f o u n d t h e compound i n a c t i v e . C o p p e r x a n t h a t e s h a v e b e e n t r i e d a s f i e l d p r o t e c t i v e f u n g i c i d e s , b u t w e r e f o u n d w a n t i n g (25) (60), A s w i l l b e e x p l a i n e d l a t e r , c o p p e r was p r o b a b l y a p a r t i c u l a r l y b a d c h o i c e o f m e t a l i n t h e s e c a s e s . On t h e o t h e r h a n d , s i n c e t h i s vrork was u n d e r t a k e n , t h e c o p p e r c o m p l e x o f c u p f e r r o n , a compound e x a m i n e d i n some d e t a i l l a t e r , ha s r e c e i v e d f a v o u r a b l e c r i t i c i s m a s a p r o t e c -t i v e f u n g i c i d e , (27), a n d a l s o a s a p r e s e r v e r o f f i s h i n g n e t s (27). Mode o f T o x i c A c t i o n o f C h e l a t e F u n g i c i d e s A p a r t f r o m o x i n e , l i t t l e w o r k has b e e n d o n e o n t h e mode o f t o x i c a c t i o n o f c h e l a t e f u n g i c i d e s . O x i n e ha s g a i n e d p a r t i c u l a r a t t e n t i o n s i n c e i t s a c t i o n a g a i n s t b a c t e r i a i s c l o s e l y r e l a t e d t o t h a t o f p e n i c i l l i n . G a l e (15) i n d e s c r i b i n g t h i s r e l a t i o n s h i p , p o i n t s o u t t h a t amino a c i d s a r e t a k e n u p b y Gram p o s i t i v e b a c t e r i a i n two w a y s , ( a ) b y s i m p l e d i f f u s i o n , ( b ) b y a n a c t i v e c e l l p r o c e s s r e q u i r i n g e n e r g y . I t i s t h i s l a t t e r energy , r e q u i r i n g t r a n s f e r o f amino a c i d e w h i c h i s i n h i b i t e d b y p e n i c i l l i n , and a l l c e l l s a b l e t o s y n t h e s i z e t h e i r own amino a c i d s a r e , a s a r e s u l t , r e s i s t a n t . Two t r a c e m e t a l s , manganese a n d m a g n e s i u m , p l a y a n e s s e n t i a l p a r t i n t h i s e n e r g y t r a n s f e r . O x i n e , b y i n a c t i v a t i n g t h e s e two m e t a l s , i s a b l e t o i n h i b i t t h e a b s o r p t i o n o f amino a c i d s . I n a c t i v a t i o n b y o x i n e o f o t h e r t r a c e m e t a l s , p a r t i c u l a r l y c o p p e r a n d z i n c , i n t e r f e r e s w i t h c e l l r e s p i r a t i o n a n d f e r m e n t a t i o n , b u t t h i s r e q u i r e s a h i g h e r c o n c e n t r a t i o n o f o x i n e t h a n t h a t r e q u i r e d t o i n h i b i t amino a c i d a b s o r p t i o n . H o r s f a l l (25) s u g g e s t e d t h a t t h e f u n g i s t a t i c a c t i o n o f o t h e r c h e l a t e s , n a m e l y q u i n o n e d i o x i n e , s a l a c y l a l d o x i n e and t h e d i t h i o c a r b a m a t e s may a l s o be due t o t h e i r a c t i o n i n p r e c i p i t a t i n g t r a c e m e t a l s . A v e r y s i g n i f i c a n t f a c t c o n c e r n i n g t h e a c t i o n o f c h e l a t e s u p o n g r o w t h has b e e n p o i n t e d o u t b y A l b e r t ( 2 ) . I n o r d e r f o r g r o w t h i n h i b i t i o n t o t a k e p l a c e , t h e t r a c e m e t a l s on a b a c t e r i a l s u r f a c e must be i n a c t i v a t e d . A p p a r e n t l y m e t a l s may b e h e l d b y a b i o l o g i c a l s u r f a c e i n s u c h a way t h a t o n l y c h e l a t e s o f a p p r o p r i a t e a r c h i t e c t u r e may h a v e a c c e s s t o t h e m . A l b e r t ( 3 ) c o n s i d e r e d t h a t t h i s a b i l i t y was l i m i t e d t o r e l a t i v e l y f e w c h e l a t e s , a n d t h a t t h e s e w e r e m a i n l y r e l a t e d t o o x i n e . N e v e r t h e l e s s , d a t a c i t e d b y H o r s f a l l (25) a n d r e s u l t s g i v e n i n t h e e x p e r i m e n t a l p a r t o f t h e p r e s e n t p a p e r , i n d i c a t e t h a t a c o n s i d e r a b l e number o f c h e l a t e s q u i t e u n r e l a t e d t o o x i n e , a r e g r o w t h i n h i b i t o r s „ Foote, et a l (14) attempted to determine the i n h i b i t o r y e f f e c t of Dithane and Arasan upon the enzyme carboxylase with the Warburg manometer. However, they reported inconclusive r e s u l t s , which they a t t r i b u t e d t o the i n s o l u b i l i t y of these compounds. function independently to tha t of metal p r e c i p i t a t i o n , i s the evolution of t o x i c gases. This type o f a c t i o n appears l i m i t e d to those chelates containing sulphur. Dimmond and H o r s f a l l (7) stated that the greater part of the t o x i c i t y of Dithane appeared to be due to the evolution o f hydrogen sulphide, and suggested the following scheme to explain the evolution of t h i s gas. MA TE (OiTHA NS) ism between nitrogen and sulphur on the one hand, and between the two sulphur atoms on the other. I n s t a b i l i t y r e s u l t e d from t h i s dynamic state, and hydrogen sulphide was s p l i t o f f . A further mode of t o x i c a c t i o n of chelates which may Hydrolysis f i r s t took place, followed by a double tautomer-This explanation was apparently accepted u n t i l r e c e n t l y Rich and H o r s f a l l (45) gave evidence that the gas given o f f by Dithane was a mixture. The second gas appeared to be even more t o x i c than h y d r o g e n s u l p h i d e . As a r e s u l t , R i c h a n d H o r s f a l l c o n c l u d e d t h a t no s a t i s f a c t o r y t h e o r y h a s y e t b e e n o f f e r e d t o e x p l a i n t h e f u n g i c i d a l m e c h a n i s m o f D i t h a n e , They e x p r e s s t h e h o p e , h o w e v e r , t h a t a c l u e may b e f o u n d b y a t t e m p t i n g t o i s o l a t e a n d i d e n t i f y t h e t o x i c g a s e s f r o m t h i s compound. As w i l l be shown l a t e r i n t h e e x p e r i m e n t a l p a r t o f t h i s w o r k , t h e s e c o n d t o x i c gas g i v e n o f f b y D i t h a n e , i s c a r b o n d i s u l p h i d e • No r e p o r t s have b e e n made o f t h e e v o l u t i o n o f g a s e s f r o m o t h e r d i t h i o c a r b a m a t e f u n g i c i d e s . H o w e v e r , i t w i l l be shown l a t e r , t h a t p r o b a b l y a l l o f t h e s e f u n g i c i d e s owe a t l e a s t a p a r t o f t h e i r e f f e c t i v e n e s s t o t h e e v o l u t i o n o f t o x i c g a s e s . L a b o r a t o r y A s s a y o f F u n g i c i d e s Two p r i n c i p a l methods f o r t h e l a b o r a t o r y a s s a y o f f u n g i c i d e s h a v e b e e n d e v e l o p e d . The f i r s t o f t h e s e i s b a s e d u p o n t h e i n h i b i t i o n o f s p o r e g e r m i n a t i o n , a n d h a s been a d o p t e d a s a s t a n d a r d method b y t h e F u n g i c i d e Commit tee o f t h e A m e r i c a n P h y t o p a t h o l o g i c a l S o c i e t y (4), The s e c o n d i s b a s e d u p o n t h e i n h i b i t i o n o f m y c e l i a l g r o w t h , a method f i r s t p r o p o s e d b y Bateman (8), and d e v e l o p e d l a t e r b y V i n c e n t (6l). The b a s i c p r i n c i p a l b e h i n d b o t h t h e s e methods i s t h e e x a m i n a -t i o n o f t h e f u n g i c i d e a t d i f f e r e n t c o n c e n t r a t i o n l e v e l s . As t h e d o s e i s i n c r e a s e d , so i s t h e i n h i b i t i o n i n c r e a s e d . When t h e p e r c e n t a g e i n h i b i t i o n i s p l o t t e d a g a i n s t c o n c e n t r a t i o n , a d o s a g e - r e s p o n s e c u r v e i s p r o d u c e d , W i l c o x o n and M c C a l l a n ( 5 5 ) have shown t h a t i f s u c h d a t a o b t a i n e d f r o m s p o r e g e r m i n a t i o n t e s t s a r e p l o t t e d o n l o g a r i t h m i c p r o b a b i l i t y p a p e r , a l i n e a r do s a g e - r e s p o n s e c u r v e r e s u l t s , , Bateman ( 8 ) o b t a i n e d s i m i l a r l i n e a r d o s a g e - r e s p o n s e c u r v e s f r o m m y c e l i a l i n h i b i t i o n d a t a b y p l o t t i n g t h e l o g s , o f c o n c e n t r a t i o n a g a i n s t l o g s , o f p e r c e n t a g e i n h i b i t i o n . The g r e a t v a l u e o f l i n e a r d o s a g e - r e s p o n s e c u r v e s i n e v a l u a t -i n g t h e f u n g i s t a t i c a c t i o n o f d i f f e r e n t compounds ha s b e e n d i s c u s s e d b y Dimond e t a l l (13), a n d r e v i e w e d b y H o r s f a l l (25) . I t a p p e a r s t h a t d i f f e r e n t f u n g i c i d e s have d i f f e r e n t d o s a g e - r e s p o n s e c u r v e s l o p e s , a n d i t i s a s sumed t h a t compounds w i t h d i f f e r e n t s l o p e s have d i f f e r e n t modes o f a c t i o n . Where d o s a g e - r e s p o n s e c u r v e s o f two f u n g i c i d e s c r o s s , a r e v e r s a l o f t h e o r d e r o f e f f e c t i v e n e s s o f t o x i c a c t i o n r e s u l t s . O t h e r f a c t o r s b e i n g e q u a l , e f f e c t i v e n e s s o f t o x i c a c t i o n o f a f u n g i -c i d e w i t h a f l a t s l o p e w i l l d e c r e a s e more s l o w l y w i t h w e a t h e r i n g , t h a n t h a t o f a f u n g i c i d e p o s s e s s i n g a s t e e p d o s a g e - r e s p o n s e c u r v e . A l t h o u g h more g e n e r a l l y u s e d , t h e s p o r e g e r m i n a t i o n method s u f f e r s t h e d i s a d v a n t a g e t h a t t h e t e s t o r g a n i s m must g e r m i n a t e b y germ t u b e . T h u s , t h e m y c e l i a l i n h i b i t i o n method must be u s e d i n e v a l u a t i n g c h e m i c a l s a g a i n s t d a m p i n g - o f f s p e c i e s o f P y t h i u m o r P h y t o p h t h o r a , s i n c e t h e s e o r g a n i s m s g e r m i n a t e b y swarm s p o r e s . EXPERIMENTAL P a r t 1 The P r e p a r a t i o n a n d E v a l u a t i o n o f C h e l a t e C o m p l e x e s  a s Seed P r o t e c t a n t F u n g i c i d e s A n a t t e m p t was made t o s y n t h e s i z e e f f e c t i v e f u n g i s t a t i c a g e n t s b y c o m b i n i n g f u n g i s t a t i c c h e l a t e r a d i c a l s w i t h m e t a l l i c i o n s . F o r t h i s p u r p o s e , a number o f c h e l a t e s were f i r s t e x a m i n e d f o r f u n g i s t a t i c a c t i v i t y , a n d t h e m o s t a c t i v e o f t h e s e s e l e c t e d f o r f u r t h e r s t u d y . The method o f m e a s u r i n g f u n g i s t a t i c a c t i v i t y was b a s e d o n t h e p r o c e d u r e d e v e l o p e d b y Ba teman ( 8 ) and V i n c e n t ( 6 1 ) . B r i e f l y , t h i s p r o c e d u r e c o n s i s t s i n d e t e r m i n i n g t h e m y c e l i a l g r o w t h r a t e o f a fungus o n a g a r p l a t e s c o n t a i n i n g s u b - l e t h a l d o s e s o f f u n g i s t a t i c a g e n t . A g a r d i l u t i o n s o f t h e t o x i c a g e n t a r e f i r s t p r e p a r e d i n P e t r i p l a t e s . When c o o l , t h e s e p l a t e s a r e i n o c u l a t e d w i t h a f u n g u s c u l t u r e . The p l a t e c u l t u r e s a r e t h e n i n c u b a t e d a l o n g w i t h c o n t r o l c u l t u r e s c o n t a i n i n g no t o x i c a g e n t , a n d r a d i a l g r o w t h measurements made o f t h e d e v e l o p i n g c o l o n i e s a t s u i t a b l e t i m e i n t e r v a l s . G r o w t h r a t e s a r e ' d e t e r m i n e d b y p l o t t i n g t h e i n c r e a s e i n d i a m e t e r o f t h e c o l o n i e s a g a i n s t i n c u b a t i o n t i m e , a n d d r a w i n g t h e b e s t s t r a i g h t l i n e t h r o u g h t h e p o i n t s . The p e r c e n t o f g r o w t h r e t a r d a t i o n o f e a c h c o n c e n t r a t i o n o f t o x i c a g e n t i s t h e n c a l c u l a t e d b y t h e f o l l o w i n g f o r m u l a : R » , c - T X 100%. C Where R=% r e t a r d a t i o n , C = g r o w t h r a t e o f c o n t r o l T= g r o w t h r a t e i n p r e s e n c e o f t o x i c a g e n t . The r e l a t i o n s h i p b e t w e e n c o n c e n t r a t i o n and p e r c e n t r e t a r d -a t i o n i s o b t a i n e d b y c o n s t r u c t i n g d o s a g e - r e s p o n s e c u r v e s . T h e s e c u r v e s a r e o b t a i n e d b y p l o t t i n g t h e r e t a r d a t i o n v a l u e s a g a i n s t c o n -c e n t r a t i o n o n l o g . p a p e r , a n d d r a w i n g t h e b e s t s t r a i g h t l i n e t h r o u g h t h e p o i n t s . P h y t o p h t h o r a e r y t h r o s e p t i c a P e t h y . was t h e t e s t o r g a n i s m u s e d t h r o u g h o u t t h i s w o r k . T h i s m o l d was c h o s e n s i n c e i t s a u i t a b l e g r o w t h r a t e and c o l o n y f e a t u r e s a l l o w e d a c c u r a t e g r o w t h m e a s u r e m e n t s , a n d b e c a u s e i t i s r e p r e s e n t a t i v e o f o r g a n i s m s c a u s i n g d a m p i n g - o f f o f s e e d l i n g s i n s o i l s . D o s a g e - r e s p o n s e c u r v e s p r o d u c e d w i t h t h i s o r g a n -i s m w e r e l i n e a r , p r o v i d i n g measurements w e r e commenced a f t e r c o l o n y d i a m e t e r h a d r e a c h e d 10 mm. , a n d t h e t o t a l i n c u b a t i o n p e r i o d d i d n o t e x c e e d f i v e d a y s . E v i d e n c e was o b t a i n e d t h a t t h e p o s i t i o n o f t h e d o s a g e -r e s p o n s e c u r v e may b e a f f e c t e d by t h e n a t u r e o f t h e a g a r medium as i l l u s t r a t e d i n T a b l e I. T a b l e I I n h i b i t i o n o f F . e r y t h r o s e p t i c a g r o w i n g o n c o r n m e a l a n d o n o a t m e a l a g a r s b y m e r c u r i c c h l o r i d e % i n h i b i t i o n o f g r o w t h C o n c e n t r a t i o n a t 50$ i n h i b i t i o n 1.1 1.2 1.5 1.7 2.0 2.3 2.6 100 m l . C o r n 29 45 60 82 1.3 M e a l Oat M e a l 25 35 47 54 2.4 The o r g a n i s m a p p e a r e d e v e n more s u s c e p t i b l e t o t h e a c t i o n o f m e r c u r i c c h l o r i d e o n a s y n t h e t i c a s p a r a g i n e m e d i u m . T h i s medium c o u l d n o t b e u s e d , h o w e v e r , s i n c e t h e m o l d grew as a n i r r e g u l a r c o l o n y , and a c c u r a t e g r o w t h measurements w e r e i m p o s s i b l e . I n o r d e r t o o b t a i n c o m p a r a b l e r e s u l t s , a l a r g e q u a n t i t y o f o a t m e a l e x t r a c t was p r e p a r e d a n d u s e d t h r o u g h o u t t h e f o l l o w i n g e x p e r i m e n t s . T h i s e x t r a c t was p r e p a r e d a c c o r d i n g t o R a w l i n s ' p r o c e d u r e (43) b y h e a t i n g 50 grams o f o a t m e a l i n one l i t e r o f w a t e r a t 70° f o r 1 h o u r . S i n c e t h e method c f m e a s u r i n g g r o w t h i n P e t r i p l a t e s n e c e s s i t a t e s a c l e a r medium, t h e e x t r a c t was f i l t e r e d . S u f f i c i e n t w a t e r was t h e n a d d e d t o p r o d u c e a f i n a l n i t r o g e n c o n t e n t d e t e r m i n e d b y t h e K j e l d h a l p r o c e d u r e o f 0 ,5$, and t h e e x t r a c t s t e r i l i z e d a t 15 l b s . p r e s s u r e f o r 20 m i n . The a g a r medium u s e d i n t h e f o l l o w i n g e x p e r i m e n t s was p r e p a r e d f r o m t h i s e x t r a c t b y a d d i n g 1 5 $ a g a r t o s u i t a b l e p o r t i o n s o f e x t r a c t , and r e - s t e r i l i z i n g t h e m e d i u m . A g a r d i l u t i o n s o f t h e t o x i c a g e n t s w e r e made b y a d d i n g t h e t o x i c a g e n t t o h o t , s t e r i l i z e d a g a r i n E r l e n m y e r f l a s k s . F i f t e e n m l . p o r t i o n s o f a g a r w e r e t h e n d i s p e n s e d i n t o P e t r i p l a t e s , f i v e p l a t e s p e r d i l u t i o n . S e e d i n g was a c c o m p l i s h e d b y p l a c i n g o n t h e c e n t r e o f e a c h a g a r p l a t e a 5 . 0 mm. d i s c o f a g a r - m y c e l i u m c u t f r o m a s e v e n d a y o a t m e a l a g a r p l a t e c u l t u r e o f P . e r y t h r o s e p t i c a . The p l a t e s w e r e i n c u b a t e d a t 24 ° C , a n d c o l o n y d i a m e t e r s m e a s u r e d a t a p p r o x i m a t e l y 24 h o u r i n t e r v a l s . I n h i b i t i o n v a l u e s o f e i g h t c h e l a t e s , a n d m e r c u r i c c h l o r i d e a r e g i v e n i n T a b l e I I . C o n c e n t r a t i o n s p r o d u c i n g f i f t y p e r c e n t i n h i b i t i o n w e r e e s t i m a t e d b y i n t e r p o l a t i o n o f t h e d o s a g e - r e s p o n s e c u r v e s d r a w n f r o m t h e s e d a t a . D a t a f r o m T a b l e I I show t h a t a l l e i g h t c h e l a t e s a r e a c t i v e f u n g i s t a t i c a g e n t s . H o w e v e r , f u n g i s t a t i c v a l u e s v a r y c o n s i d -e r a b l y , a n d o n l y c u p f e r r o n ( a m m o n i u m - n i t r o s o p h e n y l - h y d r o x y l a m i n e ) and p h e n y l - t h i o h y d a n t o i c a c i d p o s s e s s v a l u e s o f t h e same h i g h o r d e r a s t h a t o f m e r c u r i c c h l o r i d e . C u p f e r r o n a n d p h e n y l - t h i o h y d a n t o i c a c i d w e r e s e l e c t e d t h e r e f o r e a s c h e l a t e s w i t h t h e p o t e n t i a l i t i e s f o r p r o d u c i n g e f f e c t i v e f u n g i s t a t i c c o m p l e x e s w i t h m e t a l s . T a b l e I I I n h i b i t i o n o f M y c e l i a l G r o w t h o f P . e r y t h r o s e p t i c a b y C h e l a t i n g A g e n t s a n d M e r c u r i c C h l o r i d e P e r c e n t a g e I n h i b i t i o n Compound Gms. p e r l i t e r G m s . p e r l i t e r ( x l O - 2 ) ( x l C T 1 ) ** I 100 . 0 8 1 2 3 6 8 1 2 , 3 6 8 * C u p f e r r o n 30 50 98 .0002 P h e n y l t h i o -h y d a n t o i c a c i d 6 20 48 95 .005 M e r c u r i c C h l o r i d e 10 35 73 100 .004 S a l a c y l a l d -oxirae 18 30 39 98 .02 P y r o g a l l o l 85 90 94 100 .05 B e n x o i n -o x i m e 65 79 89 98 .05 D e m e t h y l -g l y o x i m e 28 40 52 80 .09 G a l l o -c y a n i n e 15 25 34 66 .11 * C u p f e r r o n c o n c e n t r a t i o n (xl0 " " l ) * * C o n c e n t r a t i o n i n gm. p e r l i t e r p r o d u c i n g 100$ g r o w t h i n h i b i t i o n . 19 P r e p a r a t i o n o f M e t a l Complexes o f C u p f e r r o n  and. P h e n y l - t h i o h y d a n t o i c a c i d C u p f e r r o n c o m p l e x e s w e r e p r e p a r e d b y a d d i n g s o l u t i o n s o f m e t a l s a l t s t o aqueous s o l u t i o n s o f c h e l a t i n g a g e n t * A l l m e t a l s a l t s w e r e i n t h e f o r m o f c h l o r i d e s , e x c e p t l e a d a c e t a t e . S u f f i c i e n t a c e t i c a c i d was added t o t h e l e a d s o l u t i o n t o p r e v e n t h y d r o l y s i s a n d p r e c i p i t a t i o n o f t h e h y d r o x i d e u p o n t h e d i l u t i o n . To 150 m l . o f a 1.0$ s o l u t i o n o f c u p f e r r o n , 200 m l . o f m e t a l s a l t s o l u t i o n w e r e a d d e d , c o n t a i n i n g f i v e t i m e s t h e e q u i v a l e n t w e i g h t o f m e t a l r e q u i r e d f o r t o t a l p r e c i p i t a t i o n . A l l m e t a l s were i n t h e d i v a l e n t s t a t e , a n d i t was assumed t h a t t h e c h e l a t e r a d i c a l s w e r e b i d e n t a t e . B y p r e c i p i t a -t i n g t h e c h e l a t e r a d i c a l c o m p l e t e l y , t e s t s f o r t h e p r e s e n c e o f c h l o r i d e o r l e a d i n t h e wash w a t e r f r o m t h e p r e c i p a t e d c o m p l e x was s u f f i c i e n t t o e s t a b l i s h p u r i t y . The p r e c i p i t a t e was a l l o w e d t o s e t t l e f o r one h o u r . F i l t e r i n g was t h e n done i n a f r i t t e r e d g l a s s f i l t e r , a n d t h e c o m p l e x washed w i t h h o t d i s t i l l e d w a t e r . W a s h i n g was c o n t i n u e d u n t i l no t e s t f o r c h l o r i d e c o u l d be o b t a i n e d i n t h e wash w a t e r w i t h s i l v e r n i t r a t e , o r l e a d w i t h h y d r o g e n s u l p h i d e . A l l c o m p l e x e s w e r e f i n a l l y d r i e d o v e r s u l p h u r i c a c i d i n a d e s i c c a t o r . P r e p a r a t i o n o f m e t a l c o m p l e x e s o f p h e n y l - t h i o h y d a n t o i c a c i d w e r e c a r r i e d o u t i n a s i m i l a r f a s h i o n t o t h o s e o f c u p f e r r o n . H o w e v e r , s i n c e t h i s c h e l a t e i s r e l a t i v e l y i n s o l u b l e i n c o l d w a t e r , p r e c i p i t a t i o n was done f r o m h o t s o l u t i o n s , a n d t h e c o m p l e x e s were washed w i t h b o i l i n g w a t e r . I n o r d e r t o i n d u c e p r e c i p i t a t i o n o f z i n c , t h e pH o f t h e z i n c c h l o r i d e was f i r s t a d j u s t e d t o pH 5.5 w i t h d i l u t e ammonium h y d r o x i d e . E v a l u a t i o n o f M e t a l Complexes b y G r e e n h o u s e E x p e r i m e n t s A n e v a l u a t i o n o f t h e m e t a l c o m p l e x e s a s s e e d p r o t e c t a n t s was t h e n made b y a p r o c e d u r e b a s e d u p o n t h a t o f M c C a l l a n ( 3 7 ) . I n o u t l i n e , t h i s p r o c e d u r e c o n s i s t e d i n d e t e r m i n i n g t h e r e l a t i v e emer-gence r e s u l t i n g f r o m seeds t r e a t e d w i t h m e t a l c o m p l e x e s when p l a n t e d i n s o i l i n f e c t e d b y t h e d a m p i n g - o f f o r g a n i s m , P y t h i u m u l t i m u m . Due t o a l i m i t e d amount o f m e t a l c o m p l e x e s a v a i l a b l e , r a d i s h s e e d s o n l y , o f S p a r k l e r v a r i e t y , were u s e d i n t h e f i r s t t e s t . Seeds were t r e a t e d w i t h .0625$ o f s e e d w e i g h t o f c h e m i c a l b y s h a k i n g i n g l a s s v i a l s f o r f i f t e e n m i n u t e s . I n f e c t e d s o i l was p r e p a r e d b y a d d i n g t o f r e s h l y s t e r i l i z e d s o i l , t h r e e d a y c u l t u r e s o f P y t h i u m u l t i m u m o n u n h u s k e d b a r l e y . A n e q u i v a l e n t o f 50 g . o f i n f e c t e d b a r l e y was added p e r f l a t o f s o i l . The f l a t s w e r e p l a c e d i n t h e g r e e n h o u s e , w a t e r e d , a n d c o v e r e d w i t h wax p a p e r f o r two d a y s . A f t e r r e m o v i n g t h e p a p e r , t h e t r e a t e d s e e d s w e r e p l a n t e d i n r a n d o m i z e d t e n - s e e d r o w s . C o n t r o l s c o n s i s t i n g o f u n t r e a t e d s e e d , s e e d t r e a t e d w i t h a s t a n d a r d s e e d p r o t e c t a n t f u n g i -c i d e A r a s a n , a n d seed p l a n t e d i n s t e r i l e s o i l w e r e i n c l u d e d . F i n a l c o u n t s o f emergence were made a f t e r t e n d a y s . T h i s t e s t was r e p e a t e d t w i c e , w i t h e s s e n t i a l l y s i m i l a r r e s u l t s . The p e r c e n t a g e emergence o b t a i n e d f r o m seeds t r e a t e d w i t h t h e d i f f e r e n t c o m p l e x e s a r e g i v e n i n T a b l e I I I . T a b l e I I I P e r c e n t a g e Emergence o f C h e l a t e - e o m p l e x T r e a t e d Seed P e r c e n t a g e Emergence M e t a l C u p f e r r o n P h e n y l - t h i o h y d a n t o i c a c i d M e r c u r y 77.5 70. Z i n c 60. 52.5 Cadmium 58.8 L e a d 61.5 Manganese 59.8 C o p p e r 60. 60. A r a s a n 65.0 C o n t r o l 45.5 S t e r i l e s o i l 74.5 L e a s t s i g n i f i c a n t d i f f e r e n c e 21% "**Mean emergence f r o m n i n e r e p l i c a t e s o f 10 s e e d r o w s . A l t h o u g h t h e p e r c e n t a g e emergence o f s eeds o b t a i n e d b y a l l . t r e a t m e n t s i s somewhat h i g h e r t h a n t h a t f r o m t h e u n t r e a t e d c o n -t r o l , o n l y t h e r e s u l t s o f t h e two m e r c u r y c o m p l e x e s a r e o u t s t a n d i n g . The a c t i o n s o f t h e t w o m e r c u r y c o m p l e x e s w e r e as a r e s u l t , examined i n more d e t a i l . U s i n g t h e t w o m e r c u r y - c o m p l e x e s w i t h A r a s a n as a c o n t r o l , a s e c o n d t e s t o f s e e d p r o t e c t a n t v a l u e s was made, u s i n g p e a s e e d o f t h e L i n c o l n v a r i e t y . S i n c e M c C a l l a n (37) r e p o r t s p a l e c o l o u r e d pea s e e d s more s u s c e p t i b l e t o d a m p i n g - o f f t h a n g r e e n s e e d s , p a l e seeds w e r e s e l e c t e d f o r u s e . Seeds w e r e t r e a t e d a t t h e f o l l o w i n g t h r e e l e v e l s , e x p r e s s e d a s p e r c e n t a g e o f s e e d w e i g h t : .015% .0625$ a n d 0 . 2 5 $ . The s e e d s w e r e p l a n t e d a s d e s c r i b e d f o r r a d i s h s e e d , and a f i n a l emergence c o u n t made a f t e r f o u r t e e n d a y s . D o s a g e - r e s p o n s e c u r v e s were d r a w n , f r o m t h e r e s u l t i n g d a t a b y t h e method o f W i l c o x o n a n d M c C a l l a n ( 5 5 ) . S i n c e r e s i s t a n c e t o d i s e a s e - i s n o r m a l l y d i s t r i -b u t e d among s e e d s , W i l c o x o n and M c C a l l a n have shown t h a t when t h e p e r c e n t a g e emergence i n t h e f o r m o f p r o b i t s i s p l o t t e d a g a i n s t l o g s , o f c o n c e n t r a t i o n , a d o s a g e - r e s p o n s e c u r v e i n t h e f o r m o f a s t r a i g h t l i n e r e s u l t s . The z o n e s o f e r r o r o f t h e ED50 ( p e r c e n t a g e d o s e f o r 50$ emergence) w e r e c a l c u l a t e d b y t h e g r a p h i c a l method o f W i l c o x o n a n d M c C a l l a n ( 5 5 ) . The r e s u l t i n g d o s a g e - r e s p o n s e c u r v e s p l o t t e d o n a l o g a r i t h m i c - p r o b a b i l i t y s c a l e a r e shown i n F i g . 1. I • PERCENT DOSAGE , ! 1 ' . . ,. i F i g , I . D o s a g e - r e s p o n s e c u r v e s „ f r o m p e a s e e d emergence t e s t s ' p l o t t e d o n l o g a r i t h m i c - p r o b a b i l i t y s c a l e f o r m e r c u r y c o m p l e x e s a n d s t a n d a r d f u n g i c i d e A r a s a n , P a r a l l e l l i n e s i n d i c a t e z o n e w i t h i n w h i c h t h e ED50 may be e x p e c t e d t o f a l l 19 t i m e s o u t o f 2 0 , u n d e r t h e same c o n d i t i o n s . P o i n t s r e p r e s e n t mean emergence o f t e n seed rows r e p l i c a t e d s i x t i m e s . F i g . I shows t h a t t h e ED50 o f P h e n y l - t h i o - h y d a n t o i c a c i d c o m p l e x i s i d e n t i c a l t o t h a t o f A r a s a n . S i n c e t h e c u r v e s c r o s s , h o w e v e r , t h e o r d e r o f f u n g i c i d a l e f f i c i e n c y o f t h e two compounds i s r e v e r s e d , A r a s a n b e i n g t h e more e f f i c i e n t above t h e p o i n t o f i n t e r -s e c t i o n , a n d t h e p h e n y l - t h i o d a n t o i c c o m p l e x b e l o w . A s i m i l a r c r o s s i n g o f t h e A r a s a n a n d c u p f e r r o n c o m p l e x c u r v e s t a k e s p l a c e i n t h e n e i g h b o u r h o o d o f 20$ e m e r g e n c e . Mode o f F u n g i s t a t i c A c t i o n o f M e r c u r y Complexes A n e x a m i n a t i o n o f t h e mode o f f u n g i s t a t i c a c t i o n o f t h e m e r c u r y c h e l a t e c o m p l e x e s f i r s t e n t a i l e d a s t u d y o f t h e c o m p o s i t i o n o f t h e s e compounds . C u p f e r r o n (ammonium n i t r o s o - p h e n o l h y d r o x y l a m i n e ) i s r e l a t e d t o n i t r o s o - p h e n o l a s shown b e l o w : AtiT&OSQ t>H£N9l. AM/"* 11 3 — N O i ! A c c o r d i n g t o S m i t h (47), C u p f e r r o n f o r m s c o - o r d i n a t i o n compounds w i t h m e t a l s a s i l l u s t r a t e d f o r t h e m e r c u r i c c o m p l e x : C VPFC Sao N ' H e Geo its Co n PLSTX , The t h e o r e t i c a l m e r c u r y c o n t e n t o f t h i s compound i s 42.3$. The a c t u a l m e r c u r y c o n t e n t o f t h e p r e p a r e d c o m p l e x , a s d e t e r m i n e d b y a m o d i f i c a t i o n o f R u p p ' s p r o c e d u r e (49), was 41»6$. The c o n t e n t o f a v a i l a b l e m e r c u r y i n i o n i z e d f o r m p r e s e n t i n a s a t u r a t e d s o l u t i o n o f t h e c o m p l e x a s d e t e r m i n e d w i t h p a r a - d i m e t h y l - b e n z a l - r h o d a n i n e r e a g e n t (48) was 4.5 p . p . m . P h e n o l - t h i o h y d a n t o i c a c i d , o r p h e n o l - t h i o u r e a - a c e t i c a c i d , i s r e l a t e d t o c a r b o n i c a c i d i n t h e f o l l o w i n g m a n n e r : AM-C ori OH A c c o r d i n g t o W i l l a r d & H a l l ( 5 6 ) , p h e n y l - t h i o h y d a n t o i c a c i d f o r m s c o - o r d i n a t i o n c o m p l e x e s w i t h d i v a l e n t m e t a l t o g i v e t h e e m p i r i c a l f o r m u l a o f t h e m e r c u r y compound a s (Co. H ^ O2 - ^2 s ) % • ^ e t h e o r e t i -c a l m e r c u r y c o n t e n t o f t h i s compound i s 32.4$. H o w e v e r , a n a l y s i s o f t h e p r e p a r e d p h e n y l t h i o h y d a n t o i c a c i d m e r c u r y c o m p l e x gave a m e r c u r y c o n t e n t o f 48.10$. T h i s r e s u l t a g r e e s c l o s e l y t o t h e t h e o r e t i c a l m e r c u r y c o n t e n t o f 48.97$ o f t h e m e r c u r o u s c o m p l e x , a s i n t h e f o r m i l l u s t r a t e d . I t a p p e a r s , t h e r e f o r e , t h a t a l t h o u g h m e r c u r i c c h l o r i d e was u s e d i n p r e p a r i n g t h e a b o v e c o m p l e x , u n d e r t h e c o n d i t i o n s o f p r e p a r a t i o n , m e r c u r y i s r e d u c e d t o t h e m e r c u r o u s f o r m . T h i s r e d u c -t i o n i s p r o b a b l y due t o t h e a c t i o n o f p r o d u c t s r e s u l t i n g f r o m s l i g h t d e c o m p o s i t i o n o f t h e c h e l a t e i n h o t s o l u t i o n s . T e s t s f o r t h e p r e s e n c e o f . . a v a i l a b l e m e r c u r y i n s a t u r a t e d s o l u t i o n s o f m e r c u r o u s - p h e n y l t h i o h y d a n t o i c c o m p l e x showed t h a t l e s s t h a n one ppm. o f i o n i z e d m e r c u r y was p r e s e n t . F r o m t h e a b o v e r e s u l t s , t h e i m p o r t a n c e o f a v a i l a b l e m e r c u r y t o t h e f u n g i s t a t i c a c t i o n o f t h e two c o m p l e x e s was e s t i m a t e d . T h i s was done b y c o m p a r i n g t h e a v a i l a b l e m e r c u r y c o n t e n t o f t h e c o m p l e x e s w i t h t h e c o n c e n t r a t i o n o f m e r c u r i c c h l o r i d e r e q u i r e d f o r t o t a l g r o w t h i n h i b i t i o n o f P . e r y t h r o s e p t i c a « The l a t t e r f i g u r e o f 33 p . p . m . m e r c u r y was o b t a i n e d b y e x t r a p o l a t i o n o f t h e d o s a g e - r e s p o n s e c u r v e d r a w n f r o m d a t a o f T a b l e I I . S i n c e a v a i l a b l e m e r c u r y i n t h e c u p f e r r o n c o m p l e x amounts t o o n l y 4.5 p . p . m . a n d l e s s t h a n 1.0 p . p . m . i n t h e p h e n y l t h i o h y d a n t o i c a c i d c o m p l e x , i t may b e a s sumed t h a t a v a i l a b l e m e r c u r y p l a y s l i t t l e p a r t i n f u n g i s t a t i c a c t i o n . N e v e r t h e l e s s , t h e r e i s t h e p o s s i b i l i t y t h a t u n d e r c e r t a i n c o n d i t i o n s , more may become a v a i l a b l e , and t h e t o x i c a c t i o n o f m e r c u r y become a p p a r e n t . The p o s s i b i l i t y o f f u r t h e r m e r c u r y b e c o m i n g a v a i l a b l e was d e t e r m i n e d b y i n v e s t i g a t i n g t h e r e l a t i v e s t a b i l i t y c o n s t a n t s o f t h e c h e l a t e m e t a l c o m p l e x e s . M e l l o r and M a l e y (32), have r e p o r t e d t h a t t h e s t a b i l i t y o r d e r o f d i v a l e n t m e t a l s w i t h a number o f c h e l a t e s f a l l i n t h e f o l l o w i n g o r d e r o f d e c r e a s i n g s t a b i l i t y : I n a f o l l o w i n g r e v i e w , M e l l o r a n d M a l e y (33) d i s c u s s e d a d d i t i o n a l e v i d e n c e t o show t h a t t h i s o r d e r i s p r o b a b l y s i m i l a r f o r a l l o r g a n i c compounds f o r m i n g s i m i l a r c o m p l e x e s . S i n c e t h e r e has b e e n no r e p o r t o n t h e r e l a t i v e s t a b i l i t y o f m e r c u r y i n c h e l a t e com-p l e x e s , t h i s was d e t e r m i n e d b y a s t u d y o f d i s p l a c e m e n t r e a c t i o n s w i t h c u p f e r r o n . P f e i f f e r (41) has p o i n t e d o u t t h a t i f some m e t a l c o m p l e x e s a r e l e s s s t a b l e t h a n o t h e r s , t h e n u n d e r s u i t a b l e c o n d i t i o n s , a m e t a l s h o u l d d i s p l a c e a n o t h e r f r o m a l e s s s t a b l e c o m p l e x . B y a method b a s e d u p o n t h e a b o v e a s s u m p t i o n , t h e r e l a t i v e s t a b i l i t i e s o f m e t a l c o m p l e x e s o f c u p f e r r o n w e r e d e t e r m i n e d . The p r o c e d u r e i n v o l v e d t h e a d d i t i o n o f m e t a l s a l t s t o c u p f e r r o n s u s p e n s i o n s , and a d e t e r m i n a t i o n o f t h e amount o f m e r c u r y d i s p l a c e d . T w e n t y m l . o f m e t a l c h l o r i d e s o l u t i o n , c o n t a i n i n g a n e q u i v a l e n t o f 1.5 x 10~3 M m e t a l , w e r e added t o 20 m l . o f aqueous s u s p e n s i o n s o f c u p f e r r o n m e r c u r y c o m p l e x i n S r l e n m y e r f l a s k s . These f l a s k s w e r e t h e n t i g h t l y c o r k e d a n d s h a k e n a t 20°C f o r 24 h o u r s . A f t e r f i l t e r i n g , t h e amounts o f m e r c u r y d i s p l a c e d b y t h e m e t a l s were d e t e r m i n e d b y a n a l y s i s o f f i l t r a t e a l i q u o t s b y t h e c o l o r -m e t r i c p a r a - d i m e t h y l o m i n o - b e n z a l - r h o d a n i n e method (48). M e t a l s w e r e s e l e c t e d w h i c h d i d n o t i n t e r f e r e w i t h c o l o r d e v e l o p e d b y m e r c u r y u n d e r t h e c o n d i t i o n s o f t h e t e s t . I n t h e p r e s e n c e o f ,0IN. n i t r i c a c i d , n e i t h e r i r o n , z i n c , c o p p e r n o r magnes ium a t a c o n c e n t r a t i o n o f 1.5xl0~^M i n t e r f e r e d w i t h t h e c o l o r m e t r i c r e a g e n t . The amounts o f m e r c u r y d i s p l a c e d f r o m t h e c u p f e r r o n c o m p l e x b y t h e s e f o u r m e t a l s a r e shown i n T a b l e I V . T a b l e I V " The R e l a t i v e Amounts o f M e r c u r y D i s p l a c e d f r o m S u s p e n s i o n o f C u p f e r r o n - m e r c u r y Complex b y D i -v a l e n t M e t a l s a t C o n c e n t r a t i o n s o f 1.5xl0~3 M . D i s p l a c i n g M e t a l C o n c e n t r a t i o n o f D i s p l a c e d M e r c u r y i n p . p . m . None 4.5 Magnes ium 16.8 I r o n 40. Z i n c 60. C o p p e r 100. Two c o n c l u s i o n s may b e d r a w n f r o m t h e s e r e s u l t s . F i r s t , i t a p p e a r s t h a t t h e m e r c u r y c o m p l e x i s l e s s s t a b l e t h a n t h e c o m p l e x e s f o r m e d f r o m t h e o t h e r f o u r m e t a l s . T h i s f o l l o w s as a r e s u l t o f a l l m e t a l s b e i n g a b l e t o d i s p l a c e m e r c u r y . The s e c o n d c o n c l u s i o n i s b a s e d u p o n t h e a s s u m p t i o n t h a t t h e m e t a l f o r m i n g t h e most s t a b l e c o m p l e x w i l l d i s p l a c e t h e most m e r c u r y . I t f o l l o w s f r o m t h i s a s sump-t i o n , t h a t t h e s t a b i l i t i e s o f m e t a l c o m p l e x e s o f c u p f e r r o n d e c r e a s e f r o m c o p p e r t o m a g n e s i u m . T h i s i s p r e c i s e l y t h e same o r d e r o f s t a b i l i t y a s M e l l o r a n d M a l e y ( 3 1 ) r e p o r t f o r t h e s e m e t a l s w i t h o t h e r c h e l a t e s . A s a r e s u l t o f t h e s e s t a b i l i t y s t u d i e s , t h e f o l l o w i n g c o n -c l u s i o n may b e made r e g a r d i n g t h e f u n g i s t a t i c a c t i o n o f a v a i l a b l e ^ -m e r c u r y i n t h e c u p f e r r o n c o m p l e x . A l t h o u g h i n d i s t i l l e d w a t e r t h e a v a i l a b l e m e r c u r y i s i n s u f f i c i e n t t o p l a y a n i m p o r t a n t r o l e i n f u n g i s t a t i c a c t i o n , i n t h e p r e s e n c e o f t r a c e s o f magnes ium o r i r o n , s u c h a s a r e l i k e l y t o b e p r e s e n t i n o r g a n i c m e d i a , s u f f i c i e n t m e r c u r y may b e d i s p l a c e d f r o m t h e c o m p l e x t o p r o d u c e a m e r c u r y t o x i c i t y . A l t h o u g h i t i s c o n c l u d e d what p a r t m e r c u r y may p l a y i n t h e t o x i c i t y o f t h e c u p f e r r o n c o m p l e x , no c o n s i d e r a t i o n has b e e n t a k e n o f t h e o r g a n i c r a d i c a l , i t s e l f a p o w e r f u l f u n g i s t a t . I n f o r m a t i o n o n t h e f u n g i s t a t i c a c t i o n o f t h e c h e l a t e r a d i c a l was o b t a i n e d b y com-p a r i n g d o s a g e - r e s p o n s e c u r v e s o f t h e c o m p l e x w i t h t h e c u r v e s o f i t s component p a r t s , c u p f e r r o n a n d m e r c u r i c c h l o r i d e . T h e s e c u r v e s , shown i n F i g , 2 w e r e o b t a i n e d w i t h P , e r y t h r o s e p t i c a a s t e s t o r g a n i s m a c c o r d i n g t o p r e v i o u s l y d e s c r i b e d m e t h o d s . CONCENTRATION - MILLIMOLES PER LITER. F i g . 2 . Dosage r e s p o n s e - c u r v e s o f f u n g i c i d e s c a l c u l a t e d f r o m d a t a o n t h e i n h i b i t i o n o f m y c e l i a l g r o w t h P e r y t h r o s e p t i c a o n a g a r p l a t e s . P o i n t s r e p r e s e n t t h e mean g r o w t h r e t a r d a t i o n r e s u l t i n g f r o m f i v e r e p l i c a t e s . I f t h e i n h i b i t o r y a c t i o n o f t h e M e r c u r y - c o m p l e x was due t o i o n i z e d m e r c u r y o n l y , t h e s l o p e o f t h e d o s a g e - r e s p o n s e s h o u l d b e s i m i l a r t o t h a t o f m e r c u r i c c h l o r i d e . T h i s f o l l o w s f r o m B a t e m a n ' s ( 8 ) w o r k i n d i c a t i n g t h a t t h e s l o p e s o f d o s a g e - r e s p o n s e c u r v e s o f s a l t s o f a t o x i c m e t a l a r e s i m i l a r r e g a r d l e s s o f a n i o n . S i n c e F i g . 2 A shows t h a t t h e s e s l o p e s a r e n o t s i m i l a r , i t f o l l o w s t h a t t h e c u p f e r r o n p o r t i o n o f t h e m o l e c u l e i s a l s o i n v o l v e d i n t h e f u n g i s t a t i c a c t i o n . The d i s p l a c e m e n t o f m e r c u r y f r o m p h e n y l - t h i o - h y d a n t o i c # a c i d c o m p l e x b y m e t a l s , was e x a m i n e d a s w i t h c u p f e r r o n . A p p a r e n t l y , m e r c u r o u s m e r c u r y f o r m s a v e r y s t a b l e c o m p l e x w i t h t h i s c h e l a t e , s i n c e m e r c u r y was n o t d i s p l a c e d b y a n y o f t h e m e t a l s a d d e d . I f i o n i z e d m e r c u r y p l a y s no p a r t i n t h e f u n g i s t a t i c a c t i o n o f t h i s com-p l e x , i s t h e a c t i o n due s o l e l y t o t h e c h e l a t e r a d i c a l ? R e f e r e n c e t o d o s a g e - r e s p o n s e c u r v e s o f F i g . I I B a g a i n , w i l l a n s w e r t h i s q u e s t i o n . I f t h e a c t i o n o f t h e m e r c u r y c o m p l e x was due t o t h e c h e l a t e m o l e c u l e o n l y , t h e n t h e s l o p e s o f b o t h t h e c h e l a t e a n d m e r c u r y - c o m p l e x c u r v e s s h o u l d be s i m i l a r . H o w e v e r , t h e c u r v e o f t h e c o m p l e x i s c o n s i d e r a b l y f l a t t e r t h a n t h a t o f p h e n y l - t h i o h y d a n t o i c a c i d . I t a p p e a r s , t h e r e -f o r e , t h a t t h e m e r c u r o u s c o m p l e x o f p h e n y l - t h i o h y d a n t o i c f u n c t i o n s n e i t h e r b y v i r t u e o f t h e c h e l a t e r a d i c a l , n o r b y m e r c u r y a l o n e , b u t r a t h e r a s a n u n d i s s o c i a t e d m o l e c u l e , A s e c o n d p r o c e d u r e was u s e d t o d e t e r m i n e t h e e f f e c t u p o n t o x i c i t y o f i n t r o d u c i n g m e r c u r y i n t o t h e c h e l a t e m o l e c u l e . T h i s method i n v o l v e d a d e t e r m i n a t i o n o f t h e r e l a t i v e g r o w t h a n d r e s p i r a t i o n i n h i b i t o r y p o w e r s o f t h e c h e l a t e s , compared t o t h o s e o f t h e i r m e r c u r y c o m p l e x e s . The c o n c e n t r a t i o n s o f t w o c h e l a t e s , t h e i r m e r c u r y c o m p l e x e s , and m e r c u r i c c h l o r i d e r e q u i r e d t o p r o d u c e 50% g r o w t h i n h i b i t i o n , w e r e o b t a i n e d b y i n t e r p o l a t i o n s f r o m t h e d o s a g e - r e s p o n s e c u r v e s o f F i g , 2 , The c o r r e s p o n d i n g c o n c e n t r a t i o n s o f t h e s e compounds r e q u i r e d t o r e d u c e r e s p i r a t i o n o f P . e r y t h r o s e p t i c a b y 50$, w e r e d e t e r m i n e d i n t h e s t a n d a r d W a r b u r g manometer b y methods b a s e d o n t h o s e o f N i c k e r s o n (40) a n d B r o n f r e b r e n n e r e t a l (6) , F o r t h i s p u r p o s e , s h a k e c u l t u r e s o f P . e r y t h r o s e p t i c a w e r e g r o w n f o r manometer r e s p i r a t i o n measurements i n t h e f o l l o w i n g m e d i u m : G l u c o s e 50 Gm. D i p o t a s s i u m p h o s p h a t e 1 .0 » M a g n e s i u m S u l p h a t e 0.02 » C a l c i u m S u l p h a t e 0.02 " A s p a r a g i n e 4.0 » T h i a m i n H y d r o c h l o r i d e 0.2 m g . T r a c e m e t a l s - Cu.05 p . p . m . Z n 1 . p . p . m . F e . l . p . p . m . Mn.05 p . p . m . W a t e r t o make 1 l i t e r pH 6.5 a d j u s t e d w i t h h y d r o c h l o r i c a c i d . C u l t u r e s were s h a k e n u n t i l m o l d g r o w t h h a d r e a c h e d a s t a g e s u i t a b l e f o r p i p e t t i n g . The m o l d m y c e l i u m was t h e n f i l t e r e d o f f , washed w i t h S o r e n s e n ' s b u f f e r o f pH 6 . 5 , a n d f i n a l l y r e - s u s p e n d e d i n b u f f e r . B y means o f a p i p e t t e , e q u i v a l e n t amounts o f m o l d w e r e t h e n added t o manometer f l a s k s . F u n g i s t a t i c a g e n t s were added t o a s i d e a r m , aqueous p o t a s h t o t h e c e n t r e w e l l , and f i n a l l y s u f f i c i e n t w a t e r added t o t h e m a i n f l a s k t o p r o d u c e a t o t a l l i q u i d v o l u m e o f t h r e e m l . The f l a s k s were t h e n p l a c e d i n t h e w a t e r b a t h a t 2 8 ° C , and s h a k e n f o r a n e q u i l i b r a -t i o n p e r i o d o f 10 m i n . The r a t e o f o x y g e n u p t a k e was d e t e r m i n e d d u r i n g t h e l i n e a r r e s p i r a t i o n p e r i o d f o r e a c h c o n c e n t r a t i o n o f c h e m i c a l . The p e r c e n t a g e i n h i b i t i o n was t h e n p l o t t e d a g a i n s t c o n c e n t r a t i o n , a n d a smooth c u r v e d r a w n t h r o u g h t h e p o i n t s . C o n c e n t r a t i o n s p r o d u c i n g 50$ r e s p i r a t i o n i n h i b i t i o n w e r e t h e n i n t e r p o l a t e d f r o m t h e s e c u r v e s . The r e s u l t i n g c o n c e n t r a t i o n o f compounds w h i c h p r o d u c e d 50$ g r o w t h i n h i b i t i o n a n d 50$ r e s p i r a t i o n i n h i b i t i o n a r e shown o n T a b l e V . T a b l e V C o n c e n t r a t i o n s o f Compounds P r o d u c i n g 50$ G r o w t h and R e s p i r a t i o n I n h i b i t i o n o f P . e r y t h r o s e p t i c a Compound C o n c e n t r a t i o n i n m o l e s p e r l i t e r (xl0~5) 50$ G r o w t h I n h i b i t i o n 50$ R e s p i r a t i o n I n h i b i t i o n M e r c u r i c C h l o r i d e C u p f e r r o n C u p f e r r o n M e r c u r y P h e n y l - t h i o -h y d a n t o i c a c i d P h e n y l - t h i o -h y d a n t o i c a c i d m e r c u r y 20. .7 10. 45. 2.5 23. 120. 90. 1000. 105.. T a b l e V shows t h a t i n t r o d u c i n g m e r c u r y i n b o t h c h e l a t e s i n c r e a s e d t h e a c t i o n o f t h e s e compounds a g a i n s t r e s p i r a t i o n . N e v e r -t h e l e s s , b o t h c h e l a t e s and t h e i r m e r c u r y c o m p l e x e s a r e more e f f e c t i v e i n h i b i t o r s o f g r o w t h , t h a n o f r e s p i r a t i o n . T h i s f a c t may e x p l a i n why c h e l a t e f u n g i c i d e s a r e g e n e r a l l y f u n g i s t a t i c r a t h e r t h a n f u n g i -c i d a l . O b v i o u s l y N i c k e r s o n ' s method (40) o f e s t i m a t i n g f u n g i s t a t i c a c t i v i t y b a s e d u p o n r e s p i r a t i o n i n h i b i t i o n , c a n n o t be a p p l i e d t o t h e s e t y p e s o f compounds . P a r t I I T o x i c G a s e s e v o l v e d f r o m C h e l a t e F u n g i c i d e s R e l a t e d t o D i t h i o c a r b a m i c A c i d ._ The i n s t a b i l i t y o f t h e d i t h i o c a r b a m a t e f u n g i c i d e s has b e e n r e c o g n i z e d f o r some t i m e . C a r b a m i c a c i d a n d d i t h i o c a r b a m i c a c i d a r e b o t h u n s t a b l e compounds : t h e f o r m e r a c i d h a s n o t been i s o l a t e d i n t h e f r e e s t a t e (46), and t h e l a t t e r decomposes i n w a t e r ( 3 8 ) . C h e r n i -k o v a n d D o b k i n a ( 9 ) showed t h a t t h e s t a b i l i t y o f t h e d i t h i o c a r b a m a t e m e t a l c o m p l e x e s p a r a l l e l e d t h a t o f t h e s u l p h i d e s . H e u b e r g e r ( 1 8 ) o o n c l u d e d t h a t t h e z i n c s a l t s were more s t a b l e t o h e a t a n d l i g h t , t h a n t h e s o d i u m , i r o n a n d c a l c i u m s a l t s , a n d t h a t t h e s e m e t a l l i c s a l t s a r e r a t h e r u n s t a b l e t o t h e a c t i o n o f a c i d s . A p a r t f r o m ' D i t h a n e , h o w e v e r , t h e e v o l u t i o n o f t o x i c g a s e s p r o d u c e d d u r i n g d e c o m p o s i t i o n h a s n o t b e e n r e p o r t e d . O n l y one o f t h e two g a s e s e v o l v e d f r o m D i t h a n e has b e e n i d e n t i f i e d (45), a n d t h e c o n d i t i o n s r e s p o n s i b l e f o r t h e d e c o m p o s i t i o n o f t h i s compound do n o t a p p e a r t o have b e e n c l e a r l y u n d e r s t o o d . D u r i n g a n a t t e m p t t o measure t h e i n h i b i t o r y a c t i o n o f s o d i u m d i e t h y l - d i t h i o c a r b a m a t e a g a i n s t t h e enzyme c a r b o x y l a s e i n t h e W a r b u r g manometer , i t was n o t i c e d t h a t a gas was e v o l v e d f r o m t h i s c h e l a t e . Due t o t h e i m p o r t a n c e a t t a c h e d b y R i c h and H o r s f a l l (45) t o ga se s e v o l v e d f r o m t h e r e l a t e d compound D i t h a n e , a n a t t e m p t was made t o i d e n t i f y t h e gas f r o m s o d i u m d i e t h y l - d i t h i o c a r b a m a t e . S i n c e t h e i d e n t i f i c a t i o n was s u c c e s s f u l , t h e s t u d y was expanded t o i n c l u d e o t h e r d i t h i o c a r b a m a t e f u n g i c i d e s , i n c l u d i n g D i t h a n e , The f o l l o w i n g e x p e r i m e n t s were d e s i g n e d t o i d e n t i f y t h e g a s e s g i v e n o f f b y t h e s e compounds , a n d t o d e t e r m i n e t h e c o n d i t i o n s o f gas e v o l u t i o n . The s o u r c e s o f t h e d i t h i o c a r b a m a t e s u s e d i n t h e f o l l o w i n g e x p e r i m e n t s w e r e : S o d i u m d i e t h y l - d i t h i o c a r b a m a t e , E a s t m a n Kodak C o , The c o p p e r , i r o n a n d z i n c c o m p l e x e s o f d i m e t h y l - d i t h i o c a r b a m a t e , b y c o u r t e s y o f C a n a d i a n I n d u s t r i e s L t d . D i t h a n e ( d i - s o d i u m e t h y l e n e - b i s - d i t h i o c a r b a m a t e ) , b y c o u r t e s y o f D r . J . G . H o r s f a l l , C o n n e c t i c u t A g r i c u l t u r a l E x p e r i m e n t S t a t i o n , Measurement s o f ga s e v o l u t i o n w e r e made i n a l l e x p e r i m e n t s i n t h e c o n v e n t i o n a l W a r b u r g manometer . E x c e p t i n s p e c i f i e d c a s e s , t h e f o l l o w i n g manometer t e c h n i q u e was a d o p t e d . One m l . o f 1 0 " ^ x 3 M d i t h i o c a r b a m a t e was added t o t h e manometer s i d e a r m , a n d 0 . 4 m l , o f b u f f e r p l a c e d i n t h e m a i n f l a s k . W a t e r was f i n a l l y a d d e d t o t h e m a i n f l a s k t o p r o d u c e a t o t a l l i q u i d v o l u m e o f 3 . 0 m l . A f t e r a n e q u i l i b r a t i o n p e r i o d o f 10 m i n u t e s i n t h e w a t e r b a t h , t h e d i t h i o c a r b a m a t e was dumped i n t o t h e b u f f e r , and gas e v o l u t i o n r e c o r d e d a t 5 m i n u t e i n t e r v a l s . A l l e x p e r i m e n t s were c a r r i e d o u t a t 2 8 ° C . S o d i u m D i e t h y l - d i t h i o c a r b a m a t e The e f f e c t o f pH u p o n gas e v o l u t i o n f r o m s o d i u m d i e t h y l -d i t h i o c a r b a m a t e was f i r s t d e t e r m i n e d . F o r t h i s p u r p o s e , a s e r i e s o f S o r e n s e n ' s p h o s p h a t e b u f f e r s r a n g i n g f r o m pH 4 , 9 t o 7 . 4 w e r e p r e p a r e d . F ig.3 shows t h e r e l a t i v e r a t e o f gas e v o l u t i o n f r o m t h e above compound i n t h e p r e s e n c e o f t h e s e b u f f e r s . S i n c e t h e gas was l a t e r i d e n t i f i e d a s c a r b o n d i s u l p h i d e , gas v o l u m e s i n F ig.3 w e r e c a l c u l a t e d o n a b a s i s o f a c a r b o n d i s u l p h i d e manometer c o n s t a n t . F i g.3. The e f f e c t o f pH o f S o r e n s e n ' s p h o s p h a t e b u f f e r u p o n gas e v o l u t i o n f r o m d i e t h y l - d i t h i o c a r b a m a t e . To d e t e r m i n e t h a t gas e v o l u t i o n was n o t l i m i t e d t o t h e a c t i o n o f p h o s p h a t e b u f f e r , a c o m p a r i s o n was made b e t w e e n t h e a c t i o n o f c i t r a t e a n d p h o s p h a t e b u f f e r on gas e v o l u t i o n . I n o r d e r t o o b t a i n g r e a t e r manometer r e a d i n g s , t h e b u f f e r c o n t e n t was i n c r e a s e d t o 6 m l . These r e s u l t s a r e shown i n F i g.4. F ig s.3 and 4 i n d i c a t e c o n c l u s i v e l y t h a t gas e v o l u t i o n i s a r e s u l t o f b u f f e r a c i d i t y . TIME —•- MINUTES. | — . . '. J F i g , 4 . The e f f e c t o f p h o s p h a t e a n d c i t r a t e b u f f e r s u p o n ga s e v o l u t i o n f r o m s o d i u m d i e t h y l d i t h i o c a r b a m a t e . The i n t e r a c t i o n o f b u f f e r w i t h d i t h i o - c a r b a m a t e was e x a m i n e d f u r t h e r b y m e a s u r i n g t h e ga s e v o l v e d i n t h e p r e s e n c e o f i n c r e a s e d amounts o f b u f f e r . A t t h e same t i m e , a n a t t e m p t was made t o i d e n t i f y t h e gas b y i t s a c t i o n o n aqueous and a l c o h o l i c p o t a s h s o l u t i o n s . F o r t h e l a t t e r p u r p o s e , 0 . 2 m l o f a 5 . 0 $ aqueous s o l u t i o n o f p o t a s h w e r e added t o t h e c e n t r e w e l l o f t h e manometer f l a s k . I n a c o r r e s p o n d i n g f l a s k , a 5 . 0 $ s o l u t i o n o f p o t a s h i n a b s o l u t e a l c o h o l was a d d e d t o t h e c e n t r e w e l l . F i l t e r p a p e r s were a d d e d i n t h e s t a n d a r d manner t o i n c r e a s e t h e r a t e o f gas a b s o r p t i o n . The r e s u l t s a r e shown i n F i g . 5 . ' -F i g . 5 . The e f f e c t o f i n c r e a s i n g amounts o f p h o s p h a t e b u f f e r o f pH 4.9 u p o n gas e v o l u t i o n f r o m s o d i u m d i e t h y l - d i t h i o c a r b a m a t e , a n d t h e r e l a t i v e a b s o r p t i o n o f t h e g a s b y aqueous and a l c o h o l i c s o l u t i o n s o f p o t a s h . The gas e v o l u t i o n r e s u l t i n g f r o m 0.9 m l . b u f f e r i n t h e p r e s e n c e a n d a b s e n c e o f aqueous p o t a s h was i d e n t i -c a l , and h e n c e o n l y one c u r v e i s s h o w n . Volumes c a l c u l a t e d o n a b a s i s o f Kcs2» F i g . 5 shows t h a t s i n c e t h e ga s i s a b s o r b e d i n s t a n t l y b y a l c o h o l i c p o t a s h , b u t n o t b y aqueous p o t a s h , t h e g a s i s n o t h y d r o g e n s u l p h i d e . C o n f i r m i n g t h i s p o i n t was t h e i n a b i l i t y o f a 20$ aqueous s o l u t i o n o f l e a d a c e t a t e t o a b s o r b t h e g a s . T h e s e r e a c t i o n s a r e , h o w e v e r , c h a r a c t e r i s t i c o f c a r b o n d i s u l p h i d e (53) . A s a r e s u l t , R e i t h ' s c o n f i r m a t o r y t e s t f o r t h e p r e s e n c e o f c a r b o n d i s u l p h i d e (44) was d o n e o n t h e a l c o h o l i c p o t a s h s o l u t i o n . One d r o p o f 1/50N c o p p e r a c e t a t e a n d 0.2 m l . o f 4N a c e t i c -a c i d w e r e added t o t h e a l c o h o l i c p o t a s h s o l u t i o n . The c h a r a c t e r i s t i c b r i g h t y e l l o w c o l o r o f c o p p e r z a n t h o g e n a t e c o n f i r m e d t h e p r e s e n c e o f c a r b o n d i s u l p h i d e - . M e t a l Complexes o f D i m e t h y l - d i t h i o c a r b a m a t e A n a t t e m p t was t h e n made t o d e t e r m i n e i f ga s e v o l u t i o n t o o k p l a c e u n d e r s i m i l a r c o n d i t i o n s , f r o m o t h e r c l o s e l y r e l a t e d f u n g i -c i d e d e r i v a t i v e s . F p r t h i s p u r p o s e , t h e c o p p e r , z i n c , a n d i r o n c o m p l e x e s o f d i m e t h y l - d i t h i o c a r b a m a t e , were e x a m i n e d . One m l . s u s p e n s i o n s o f t h e s e compounds w e r e added t o t h e manometer s i d e a r m s , a n d two m l . o f S o r e n s e n ' s p h o s p h a t e b u f f e r pH 4.9 p l a c e d i n t h e m a i n f l a s k . Gas e v o l u t i o n was t h e n measured i n t h e u s u a l m a n n e r . No c a r b o n d i s u l p h i d e e v o l u t i o n c o u l d be d e t e c t e d f r o m t h i s c o p p e r c o m p l e x . The r e l a t i v e e v o l u t i o n o f gas f r o m t h e i r o n a n d z i n c c o m p l e x e s a r e shown i n F i g . 6 , 41 T I M E — H O U R S . F i g . 6 . Gas e v o l u t i o n f r o m m e t a l c o m p l e x e s o f d i m e t h y l - d i t h i o c a r b a m i c a c i d i n t h e p r e s e n c e o f p h o s p h a t e b u f f e r o f pH 4.9. V o l u m e s c a l -c u l a t e d o n b a s i s o f KcS2* The g a s g i v e n o f f f r o m b o t h t h e s e c h e l a t e c o m p l e x e s was i d e n t i f i e d b y t h e methods p r e v i o u s l y d e s c r i b e d a s c a r b o n b i s u l p h i d e . A t t h e same t i m e i t was n o t i c e d t h a t t h e d e c o m p o s i t i o n o f t h e s e two n e u t r a l compounds was a c c o m p a n i e d b y a r i s e i n pH o f t h e b u f f e r m i x t u r e . I t was c o n s i d e r e d p o s s i b l e , t h e r e f o r e , t h a t a n a n i n e m i g h t r e m a i n i n t h e b u f f e r s o l u t i o n a s a s e c o n d a r y d e c o m p o s i t i o n p r o d u c t . As a r e s u l t , a n a t t e m p t was made t o i s o l a t e a n d i d e n t i f y t h e p r o d u c t r e s u l t i n g , f r o m t h e d e c o m p o s i t i o n o f t h e s o l u b l e s o d i u m d i e t h y l - d i t h i o -c a r b a m a t e i n t h e f o l l o w i n g m a n n e r : Sodium diethyl-dithiocarbamate was decomposed with evolu-t i o n o f carbon disulphide by adding slowly .01N hydrochloric a c i d u n t i l pH of 3.0 was produced. The s o l u t i o n was then evaporated to dryness, and the residue washed with ether. A f t e r drying a second time, the residue was then extracted with chloroform. On evaporation, the chloroform s o l u t i o n l e f t a p e r f e c t l y white, s e m i - c r y s t a l l i n e mass producing the c h a r a c t e r i s t i c reaction of an amine s a l t (42). The com-pound produced a sharp melting point of 118.2°C, which compares cl o s e l ; to that of H9-20°C reported f o r diethylamine hydrochloride (21). dithio-carbamate fungicides decompose i n the presence of weakly a c i d i c buffers i n the following manner: Hydrolysis f i r s t takes place. Probably as a r e s u l t of dithiocarbamic a c i d i t s e l f being unstable the d e r i v a t i v e formed on hydrol y s i s then breaks down to form a dialkyamine, and simultaneously s p l i t s o f f carbon-disulphide. I t was concluded, therefore, that the d i a l k y l s e r i e s o f F i g . 6 i l l u s t r a t e s a n o t h e r i n t e r e s t i n g f e a t u r e r e g a r d i n g t h e r e l a t i v e r a t e o f d e c o m p o s i t i o n o f t h e m e t a l c o m p l e x e s . I n P a r t I o f t h i s p a p e r , i t was m e n t i o n e d t h a t t h e s t a b i l i t y o r d e r o f d i v a l e n t m e t a l s w i t h c h e l a t e s a p p e a r e d t o b e s i m i l a r , r e g a r d l e s s o f t h e c h e l a t e r a d i c a l . I f t h i s f a c t a p p l i e s a l s o t o t h e c o m p l e x e s o f d i m e t h y l d i t h i o c a r b a m a t e s , t h e r a t e o f c a r b o n d i s u l p h i d e e v o l u t i o n f r o m t h e t h r e e compounds e x a m i n e d s h o u l d f a l l i n t h e f o l l o w i n g i n c r e a s i n g o r d e r f r o m c o p p e r t o i r o n : C^c -*ZZ ~Z.n <^ /^G • I t was a l r e a d y m e n t i o n e d t h a t no c a r b o n d i s u l p h i d e c o u l d be d e t e c t e d f r o m t h e v e r y s t a b l e c o p p e r compound . H o w e v e r , F i g . 6 i n d i c a t e s t h a t t h e s t a b i l i t i e s o f t h e z i n c and i r o n c o m p l e x e s a r e r e -v e r s e d , s i n c e t h e z i n c compound decomposes more r a p i d l y t h a n t h e i r o n compound. H o w e v e r , P f e i f f e r e t a l , (41), r e p o r t e d t h e f e r r i c c o m p l e x o f b i s - s a l a c y l a l d e h y d e - e t h y l e n e d i a m e n e more s t a b l e t h a n t h e z i n c c o m p l e x , M a l l o r a n d M a l e y (33), comment ing o n t h e r e v e r s a l o f t h e s t a b i l i t y o f t h e i r o n c o m p l e x , c o n c l u d e d t h a t t h i s was u n d o u b t e d l y due t o t h e i r o n b e i n g i n t h e f e r r i c s t a t e . As t h e i r o n c o m p l e x o f d i m e t h y l * d i t h i o c a r b a m a t e e x a m i n e d was a l s o i n t h e f e r r i c s t a t e , i t a p p e a r s t h a t t h e r a t e o f d e c o m p o s i t i o n o f t h e t h r e e d i t h i o c a r b a m a t e c o m p l e x e s a g r e e s w i t h t h e g e n e r a l o r d e r o f m e t a l c h e l a t e c o m p l e x s t a b i l i t i e s . D i t h a n e T e s t s w e r e f i n a l l y made i n t h e W a r b u r g manometer f o r e v o l u -t i o n o f gases f r o m D i t h a n e i n t h e p r e s e n c e o f a n a c i d b u f f e r . The c o n c e n t r a t i o n o f f u n g i c i d e and o t h e r c o n d i t i o n s were i d e n t i c a l t o t h o s e d e s c r i b e d f o r t h e i r o n a n d z i n c c o m p l e x e s . F l a s k s c o n t a i n i n g aqueous and a l c o h o l i c p o t a s h were i n c l u d e d a s p r e v i o u s l y d e s c r i b e d . The r e s u l t s o f t h i s e x p e r i m e n t a r e shown i n F i g , 7 , 1 5 0 \ ° 75 ALCOHOLIC KOH. _ 10. 15 20 2 5 • -o. T I M E — M I N U T E S . 35 » o F i g , 7 . The e v o l u t i o n o f g a s e s f r o m D i t h a n e i n t h e p r e s e n c e o f S o r e n s e n ' s p h o s p h a t e b u f f e r o f pH ,4.9, and t h e r e l a t i v e a b s o r p t i o n o f t h e two g a s e s b y aqueous a n d a l c o h o l i c p o t a s h . F o r method o f c a l c u l a t i n g vo lume o f gas m i x t u r e see t e x t . S i n c e t h e g a s e v o l v e d f r o m D i t h a n e was a m i x t u r e , l a t e r i d e n t i f i e d a s c a r b o n s u l p h i d e a n d h y d r o g e n s u l p h i d e , t h e vo lume o f t h e t o t a l gas c o u l d n o t b e e s t i m a t e d d i r e c t l y . T h i s f o l l o w s as a r e s u l t o f t h e manometer c o n s t a n t b e i n g b a s e d u p o n t h e s o l u b i l i t y o f t h e gas b e i n g m e a s u r e d . The t o t a l gas v o l u m e o f F i g . 7 was t h e r e -f o r e c a l c u l a t e d i n t h e f o l l o w i n g manner : From manometer A , c o n t a i n i n g aqueous p o t a s h , t h e v o l u m e o f c a r b o n d i s u l p h i d e was c a l c u l a t e d , u s i n g KQS-?. F rom manometer B , c o n -t a i n i n g no p o t a s h , t h e t o t a l manometer change due t o e v o l u t i o n o f b o t h g a s e s was r e c o r d e d . The manometer change o f B , c o r r e s p o n d i n g t o t h e v o l u m e o f C S 2 o b t a i n e d f r o m A , was n e x t c a l c u l a t e d . T h e n t h e t o t a l manometer c h a n g e o f A , l e s s t h e c a l c u l a t e d manometer change d u e t o C S 2 , e q u a l l e d t h e change due t o B>>S. T h i s r e s u l t , m u l t i p l i e d b y K j ^ S f o r manometer B , g a v e t h e h y d r o g e n s u l p h i d e e v o l v e d . F i g , 7 shows t h a t t h e gas i s o n l y p a r t i a l l y a b s o r b e d b y aqueous p o t a s h . A d d i t i o n o f l e a d a c e t a t e t o t h e aqueous p o t a s h s o l u -t i o n p r o d u c e d a b l a c k . p r e c i p i t a t e o f l e a d s u l p h i d e , i n d i c a t i n g t h a t t h e p o r t i o n o f gas a b s o r b e d b y aqueous p o t a s h was h y d r o g e n s u l p h i d e . F i g , 7 i n d i c a t e s a l s o t h a t a l t h o u g h t h e gas i s e v e n t u a l l y t o t a l l y a b s o r b e d b y a l c o h o l i c p o t a s h , t h e r e i s a c o n s i d e r a b l e l a g p e r i o d . T h i s c o n t r a s t s w i t h t h e i m m e d i a t e a b s o r p t i o n o f c a r b o n d i s u l p h i d e b y t h i s s o l u t i o n i n p r e v i o u s e x p e r i m e n t s . S i n c e , h o w e v e r , t r a c e s o f w a t e r i n t e r f e r e w i t h a b s o r p t i o n o f c a r b o n d i s u l p h i d e b y a l c o h o l i c p o t a s h , i t was c o n s i d e r e d p o s s i b l e t h a t h y d r o g e n s u l p h i d e m i g h t d o t h e same. A s .a r e s u l t , i t was d e c i d e d t o t e s t f o r t h e p r e s e n c e o f c a r b o n d i s u l p h i d e i n t h e a l c o h o l i c s o l u t i o n , b y R e i t h ' s P r o c e d u r e (44), ' S i n c e R e i t h ' s t e s t f o r c a r b o n d i s u l p h i d e c a n n o t b e c a r r i e d o u t i n t h e p r e s e n c e o f h y d r o g e n s u l p h i d e , i t was f i r s t n e c e s s a r y t o remove t h i s g a s . T h i s was a c c o m p l i s h e d b y a d d i n g aqueous p o t a s h t o t h e c e n t r e w e l l o f t h e manometer i n t h e u s u a l w a y . A t t h e same t i m e , h o w e v e r , a f o l d e d f i l t e r p a p e r s t r i p was p l a c e d i n a s i d e a r m o f t h e f l a s k and t h e s i d e a r m s t o p p e d w i t h a v e n t e d p l u g , D i t h a n e was a d d e d t o t h e s e c o n d s i d e a r m , a n d b u f f e r p l a c e d i n t h e m a i n f l a s k a s b e f o r e The e v o l u t i o n o f gas was r e c o r d e d u n t i l no f u r t h e r change i n r e a d i n g s o c c u r r e d . I n o r d e r t o a b s o r b t h e l a s t t r a c e o f h y d r o g e n s u l p h i d e , s h a k i n g was c o n t i n u e d f o r a f u r t h e r h a l f h o u r . B y means o f t h e v e n t e d p l u g , 0.2 m l o f a l c o h o l i c p o t a s h s o l u t i o n was t h e n r u n i n t o t h e s i d e aim, a n d s h a k i n g was a g a i n c o n t i n u e d f o r a n o t h e r h a l f h o u r . R e i t h ' s t e s t f o r t h e p r e s e n c e o f c a r b o n d i s u l p h i d e i n t h e a l c o h o l i c p o t a s h was t h e n made b y a d d i n g t h e a c e t i c a c i d and c o p p e r a c e t a t e s o l u t i o n s d i r e c t l y t o t h e s i d e a r m c o n t a i n i n g t h e p a p e r . The c h a r a c t e r i s t i c y e l l o w c o l o r i n d i c a t i n g c a r b o n d i s u l p h i d e was p r o d u c e d . A s a r e s u l t o f t h e s e e x p e r i m e n t s , i t was c o n c l u d e d t h a t D i t h a n e decomposes w i t h e v o l u t i o n o f h y d r o g e n s u l p h i d e a n d c a r b o n d i s u l p h i d e i n t h e p r e s e n c e o f w e a k l y a c i d b u f f e r i n t h e f o l l o w i n g f a s h i o n . 47 f v H6jH i < C — N A S f s » c -r- I \ SOLPWOG D/Sc>4,^H/Di • f TH400GBA H Following hydrolysis, ethylene bis-dithiocarbamic acid i s formed. This compound, i n h e r i t i n g the i n s t a b i l -i t y o f dithiocarbamic a c i d , breaks down to form ethylene-thiourea, carbon disulphide, and hydrogen sulphide. This mode of breakdown i s substantiated by two a d d i t i o n a l f a c t s . F i r s t , i t has already been mentioned that ethylene-thiourea i s the only compound i d e n t i f i e d i n the breakdown debris of Dithane ( 4 5 ) , And second, the one to one r a t i o of hydrogen sulphide to carbon dioxide evolved i n theory, approaches the 1.2 to 1.0 obtained i n p r a c t i c e . (See Fig. 7 ) . This l a t t e r r a t i o may be considered an approximation only, since i t i s calculated from readings imrolving two f l a s k s , and hence the p i p e t t i n g of two supposedly equal portions of i n s o l u b l e Dithane i n the form o f water suspensions. DISCUSSION The r e s u l t s o f P a r t I o f t h i s p a p e r show t h a t a c t i v e f u n g i s t a t i c compounds may be p r e p a r e d b y c o m b i n i n g f u n g i s t a t i c c h e l a t e s w i t h m e t a l s . O b s e r v a t i o n s f r o m P a r t I I , i n d i c a t e t h a t p r o b a b l y a l l a c t i v e d i t h i o c a r b a m a t e f u n g i c i d e s decompose w i t h e v o l u t i o n o f t o x i c g a s e s . The i m p l i c a t i o n s o f t h i s f a c t a r e t h a t s u l p h u r compounds e n j o y a p a r t i c u l a r l y f a v o u r a b l e p o s i t i o n i n t h e c h e l a t e f u n g i c i d e f i e l d . F o r e c o n o m i c r e a s o n s a l r e a d y d i s c u s s e d , t h e two m e r c u r y c o m p l e x e s examined i n t h i s p a p e r must o f n e c e s s i t y be l i m i t e d t o u s e as seed p r o t e c t a n t s . On t h e o t h e r h a n d , t h e r e l a t i v e l y i n e x p e n s i v e s o d i u m a n d i r o n c o m p l e x e s o f t h e d i t h i o -c a r b a m a t e s , i n s p i t e o f t h e a b s e n c e o f a t o x i c m e t a l , a r e a c t i v e f u n g i c i d e s w h i c h c a n be u s e d e c o n o m i c a l l y b o t h a s s eed p r o t e c t a n t s and a s f i e l d p r o t e c t a n t f u n g i c i d e s . The e f f e c t i v e n e s s ' o f t h i s l a t t e r t y p e o f compound a p p e a r s u n d o u b t e d l y t o b e due t o t o x i c gas e v o l u t i o n . A s e a r c h f o r o t h e r s u l p h u r c h e l a t e s e v o l v i n g t o x i c g a s e s u p o n d e c o m p o s i t i o n , w o u l d a p p e a r t o b e a p r a c t i c a l a p p l i c a t i o n o f t h e s e s t u d i e s . R e f e r e n c e t o t h e c h e l a t e s t a b i l i t y o r d e r o f M e l l o r a n d M a l e y s h o u l d f a c i l i t a t e t h e p r e p a r a t i o n o f m e t a l c o m p l e x e s f r o m t h e s e s u l p h u r c h e l a t e s p o s s e s s i n g t h e d e s i r e d f u n g i s t a t i c a c t i v i t y . The g r e a t v a l u e o f t h i s m e t a l s t a b i l i t y o r d e r i n b o t h e x p l a i n i n g t h e p r e d i c t i n g t h e a c t i o n o f t h i s t y p e o f f u n g i c i d e h a s n o t y e t b e e n a p p r e c i a t e d . Lf- <j BIBLIOGRAPHY A l b e r t , A . a n d G l e d h i l l , U . S . The c h o i c e o f c h e l a t e - a g e n t f o r i n a c t i v a t i n g t r a c e m e t a l s . A l b e r t , A . , and M a g r a t h , D . The c h o i c e o f c h e l a t f r a g e n t f o r i n a c t i v a t i n g t r a c e m e t a l s . 2. D e r i v a t i v e s o f o x i n e ( 8 - h y d r o x y q u i n o l i n e ) . B i o c h e m . J . 41: 534-545. 1947. 3 A l b e r t , A . , R u b b o , S . D . , G o l d a c r e , R . J . a n d B a l f o u r , B . G . The i n f l u e n c e o f c h e m i c a l c o n s t i t u t i o n o n a n t i - b a c t e r i a l a c t i v i t y . P a r t I I I . A s t u d y o f 8 - h y d r o x y q u i n o l i n e ( o x i n e ) a n d r e l a t e d compounds . B r i t . J . E x p . P a t h . 28.69-74. 1947. A m e r i c a n P h y t o p a t h . Soc ,Comm. o n S t a n d a r d i z a t i o n o f F u n g i c i d a l T e s t s . The s l i d e g e r m i n a t i o n method o f e v a l u a t i n g , p r o t e c t a n t f u n g i c i d e s . P h y t o p a t h . 33: 627-632. 1943. 5 A m e r i c a n P h y t o p a t h S o c . U . S . D . - A . P l a n t D i v . R e p t . Vol.34(7): 215. 1950. B r o n f e r i b r e n n e r , J . , H e r s h e y , A . D . , and D o u b l y , J . A . E v a l u a t i o n o f g e r m i c i d e s b y a m a n o m e t r i c m e t h o d . P r o c . S o c . E x p . B i o l , a n d M e d . 38: 210-212. 1938. 7. B a r r a t t , R . W . , and H o r s f a l l , J . G , F u n g i c i d a l M e c h a n i s m o f D i s o d i u m e t h y l e n e - b i s d i t h i o c a r b a m a t e . P h y t o p a t h . 47: 2. 1947. ( A b s t r a c t ) . 8 Ba teman , E , The e f f e c t o f c o n c e n t r a t i o n o n t h e t o x i c i t y o f c h e m i c a l s t o l i v i n g o r g a n i s m s , U . S . D . A . T e c h n i c a l B u l l . 346. 1933. 9 G h e r n i k o v , Y . A . , a n d D o b k i n a . Use o f s o d i u m - d i e t h y l - d i t h i o -c a r b a m a t e i n a n a l y t i c a l c h e m i s t r y . Z a v o d s k a y a L a b . 15: 1143-1149. 1949. 5 u i i 10 C u n n i n g h a m , H . S . , and S h a r v e l l e , E . G . O r g a n i c s eed p r o t e c t a n t s f o r l i m a b e a n s . P h y t o p a t h , 30: 4. 1940. 11 D e s h a , L . J . O r g a n i c C h e m i s t r y . M c G r a w - H i l l , N . Y . 1936. 12 D i m o n d , E . A . , H e u b e r g e r , J . W . , and H o r s f a l l , J . G . A w a t e r s o l u b l e p r o t e c t a n t f u n g i c i d e w i t h t e n a c i t y . P h y t o p a t h 33: 1095.-1097. 1943. 13 D imond , E . A . , H e u b e r g e r , J . W . , a n d S t o d d a r d , E . M . R o l e o f t h e d o s a g e - r e s p o n s e c u r v e i n t h e e v a l u a t i o n o f f u n g i c i d e s . C o n n e c t i c u t A g r « E x p . S t a . B u l l . 451: 635-667. 1941. 14 F o o t e , M . W . , L i t t l e , J . E . , and S p r o s t o n , T . J . On n a p h t h a q u i n o n e s a s i n h i b i t o r s o f s p o r e g e r m i n a t i o n o f f u n g i . J . B i o l . Chem. 181: 481-487. 1947. . . 15 G a l e , F . E . The a s s i m i l a t i o n o f a m i n o - a c i d s b y b a c t e r i a . 8. T r a c e m e t a l s i n g l u t a m i c a c i d a s s i m i l a t i o n and t h e i r i n a c t i v a t i o n b y 8 - h y d r o x y q u i n o l i n e . J . G e n . M i c r o b i o l o g y 3: 369-386. 1949. 16 G o l d s ^ r o r t h y , M . C , G r e e n , E . L . a n d S m i t h , M . A . F u n g i c i d a l a n d p h y t o c i d a l p r o p e r t i e s o f some m e t a l d i a l k y l d i t h i o c a r b a m a t e s . J . A g r i c . R e s.66: 277-291. 1943. 17 H e a l d , F . D . . I n t r o d u c t i o n t o P l a n t P a t h o l o g y . M c G r a w - H i l l , N . Y . 1943. 18 H e u b e r g e r , J . W . P i t h i o c a r b a m i c a c i d d e r i v a t i v e s a s . f u n g i c i d e s a n d i n s e c t i c i d e s . U . S . D e p t . A g r i c . P l a n t D i s . R e p t r . S u p . . , 157:. 156-161. , 1945. 19 H e u b e r g e r , J . W . a n d H o r s f a l l , J . G . R e l a t i o n o f p a r t i c l e s i z e and c o l o r t o f u n g i v i d a l and p r o t e c t i v e v a l u e o f c u p r o u s o x i d e s . P h y t o p a t h . 29: 303-321. 1939. 20 H i l t n e r , L . U b e r d i W i r k u n g v o n c h i n o s o l und F o r m a l d e h y d a l s B e i z m i t t e l gegen d e n F u s a r i u m b e f a l l de s G e t r e i d e s . P r a k t . B l a t t e r 12: 77-80. 1914. 21 Hodgman, C . D . Handbook o f C h e m i s t r y a n d P h y s i c s . C h e n . R u b b e r P u b . C l e a v e l a n d , O h i o . 1947. 22 H o r s f a l l , J . G . Red o x i d e o f c o p p e r as a d u s t , f u n g i c i d e f o r c o m b a t i n g d a m p i n g - o f f b y s e e d t r e a t m e n t . N . Y . (Geneva ) A g r . E x p . S t . B u l l . 615. 1932. i i i 23 H o r s f a l l , J . G . Z i n c o x i d e as a s eed .and s o i l t r e a t m e n t f o r d a m p i n g - o f f . ( A b s t r . ) P h y t o p a t h , 24: 12. 1934. 24 H o r s f a l l , J . G . C o m b a t i n g d a m p i n g - o f f . - N . Y . (Geneva) A g r . E x p . S t a . B u l l . 6S3. 1938. 25 H o r s f a l l , J . G . F u n g i c i d e s a n d t h e i r a c t i o n . C h r o n i c a B o t a n i c a , W a l t h a m , M a s s . 1945. 26 H o r s f a l l , J . G . , a n d Z e n t m y e r , G . A . F u n g i c i d a l r e a g e n t s f o r amino a c i d s , a m i n e s , a l d e h y d e s , a n d o t h e r r e a c t i v e c e l l c o n s t i t u e n t s . P h y t o p a t h 34: 1004. 1944. ( A b s t . ) 27 I l l m a n , W . J . , S e m e n i u k , G . , N e i s h , A . C , a n d L e d i n g h a m , G . A , R o t r e s i s t a n c e o f c o t t o n d u c k t r e a t e d w i t h c h e l a t e c o p p e r compounds . C a n . J . R e s . F ,26: 311-317. 1948. 28 Kadow, K . J . , a n d A n d e r s o n , H . W . D a m p i n g - o f f c o n t r o l . A n e v a l u a t i o n o f s e e d and s o i l t r e a t m e n t . 111. A g r . E x p . S t a . B u l l . 439. 1937. 29 L e u k e l , R . W . R e c e n t D e v e l o p m e n t s i n s e e d t r e a t m e n t . B o t . R e v . 14 (5): 235-269. 1948. 30 M a r t i n , H . The S c i e n t i f i c P r i n c i p l e s o f P l a n t p r o t e c t i o n . Edward A r n o l d and C o . L o n d o n . 1928. 31 M a r t i n H..> W a i n , R . L . a n d W i l k i n s o n , E . H . S t u d i e s u p o n t h e c o p p e r f u n g i c i d e s V . A c r i t i c a l e x a m i n a t i o n o f t h e f u n g i c i d a l v a l u e o f c o p p e r compounds . A n n . A p p l . B i o l . 412-43.8. 1942. 32 M e l l o r , D . P . , a n d M a l e y , L . S t a b i l i t y c o n s t a n t s o f t h e i n t e r n a l c o m p l e x e s . N a t u r e . 159: 370. 1947. 33 M e l l o r , D . P . , a n d M a l e y , L . I b i d . 161: 436-437. 1948. 34 M o r g a n , G . T . , a n d Drew, H . D . K . R e s e a r c h e s o n R e s i d u a l a f f i n i t y a n d c o - o r d i n a t i o n P a r t I I . A c e t y l a c e t o m . e s o f S e l e n i u m and T e l u r i u m . J . C h e n . S o l . 117 a n d 1 1 8 : 1456-1465. 1920. 35 M c C a l l a n , S . E . A . O u t s t a n d i n g d i s e a s e s o f a g r i c u l t u r a l c r o p s and u s e s o f f u n g i c i d e s i n t h e U n i t e d S t a t e s . C o n t r i b . B o y c e Thompson I n s t . 14 (3): 105-116. 1946. 36 M c C a l l a n , S . E . A . What e v e r y d e a l e r s h o u l d know a b o u t f u n g i c i d e s . A g r i c . C h e m i c a l s 3 (7): 23-25,.77, 79. 1948. i v 37 M c C a l l a n , S . E . A . E v a l u a t i o n o f c h e m i c a l s a s s e e d p r o t e c t a n t s b y g r e e n h o u s e t e s t s w i t h pea s a n d o t h e r s e e d s , C o n t r i b . B o y c e Thompson I n s t . 15 (2): 91-117. 1948. 38 McNew, G . L , The v a l u e o f s c i e n t i f i c e x p e r i e n c e . The C a n n e r 96 (19): 16,18,24,26. 1943. 39 McNew, G . L . G r o w t h s t i m u l a t i o n o f peas b y t e t r a c h l o r o -b e n z o q u i n o n e , a f u n g i c i d a l seed t r e a t m e n t . S c i e n c e 96: 118-119. 1942. 40 N i c k e r s o n , W . J . I n h i b i t i o n o f f u n g u s r e s p i r a t i o n : A m e t a b o l i c b i o - a s s a y m e t h o d . S c i e n c e , 103: 484-486. 1946. 41 P f e i f f e r , P . , T h i e t e r t , H . , and G l a s e r , H . G e g e n s e i t i g e r A u s t a n a c h v o n M e t a l l e n i n i n n e r e n K o m p l e x s a l z e n . J . P r a k t . Chem. 152: 145-156. 1939. 42 P o r t e r , C . W . S t e w a r t , T . D . , and B r a n c h , G . E . K . The methods o f o r g a n i c c h e m i s t r y . G i n n and C o . B o s t o n . 1927. 43 R a w l i n s , T . E , P h y t o p a t h o l o g i c a l a n d B o t a n i c a l R e s e a r c h M e t h o d s . J o h n W i l e y , N . Y . 1933. 44 R e i t h , J . F . R e c u e i l d e s t r a v e a u x c h i m i q u e s de s P a y s - B a s . 53: 18-23. 1934. 45 R i c h , S . , a n d H o r s f a l l , J . G , Gaseous t o x i c a n t s f r o m o r g a n i c s u l p h u r compounds . A m e r . J . B o t . 37: 643-650. 1950. 46 R i c h t e r , G . H . T e x t b o o k o f O r g a n i c C h e m i s t r y . J o h n W i l e y , N . Y . 1947. 47 S m i t h , G . F . C u p f e r r o n a n d N e o - c u p f e r r o n . G . F . S m i t h C h e m i c a l C o . C o l u m b u s . 1938. 48 S t a f f o r d , N . , and W y a t t , P . F . A c o l o r i m e t r i c method f o r t h e d e t e r m i n a t i o n o f m i n u t e amounts o f m e r c u r y i n o r g a n i c m a t t e r . A n a l y s t 61: 529-535. 1936. 49 S t o v i t e r , H . A * , - M c N a b b , W . M . , and W a g n e r , E . C . D e t e r m i n a t i o n o f m e r c u r y i n o r g a n i c compounds . J o u r . I n d . a n d E n g . C h e m . A n a l . E d . 13: 890-893. 1941. 50 T a y l o r , C . F . , and R u p e r t , J . A . A s t u d y o f v e g e t a b l e s e e d p r o t e c t a n t s . P h y t o p a t h . 36: 726-749.- 1946. .6 3 . • 51 T a y l o r , C , F . , a n d R u p e r t , J . A . , a n d L e a c h , J . G . T e t r a m e t h y1 - t h i u r a m d i s u l p h i d e and f e r r i c d i m e t h y l d i t h i o c a r b a m a t e as s eed p r o t e c t a n t s o n v e g e t a b l e s , P h y t o p a t h . 33: 14. 1943. ( A b s t r . ) 52 T i s d a l e , W . H . , a n d W i l l i a m s , J . D i s i n f e c t a n t . U . S . P a t e n t 1, 972, 961. 1934. 53 T r e a d w e l l , E . P . and H a l l , W . T . A n a l y t i c a l C h e m i s t r y . J o h n W i l e y , N . Y . 1945. 54 W e l c h e r , F . J . O r g a n i c A n a l y t i c a l R e a g e n t s . V o l s . 1 - l v v D . v a n N o s t r a n d , T o r o n t o . 1948. 55 W i l c o x o n , F . a n d M c C a l l a n , S . E . A . T h e o r e t i c a l p r i n c i p l e s u n d e r l y i n g l a b o r a t o r y t o x i c i t y t e s t s o f f u n g i c i d e s . C o n t r i b . B o y c e Thompson I n s t . 10 (3): 329-338. 1939. 56 W i l l a r d , H . H . , a n d H a l l , D . The s e p a r a t i o n a n d d e t e r m i n a t i o n o f c o b a l t . 1. The s e p a r a t i o n o f c o b a l t b y means o f p h e n y l - t h i o h y d a n t o i c a c i d . J o u r . A m e r . Chem. S o c . 44: "2219-2226. 1922. 57 Z e n t m y e r , G . A . M e c h a n i s m o f a c t i o n o f 8 - h y d r o x y q u i n o l i n e . P h y t o p a t h . 33: 1121. 1943. 58 Z e n t m y e r , G . A . I n h i b i t i o n o f m e t a l c a t a l y s i s a s a f u n g i s t a t i c m e c h a n i s m . S c i e n c e 100: 294-295. 1944. 59 Zoe and S a r v e r . S u b s t i t u t e M e l l a n , A . O r g a n i c R e a g e n t s i n I n o r g a n i c A n a l y s i s . P h i l a d e l p h i a : The B l a k i s t o n C o . 1941. 60 G o l d s w o r t h y , M . C . , C a r t e r , R . H . , & G r e e n , E . L . The f u n g i c i d a l a n d p h y t o c i d a l p r o p e r t i e s o f some c o p p e r x a n t h a t e s . P h y t o p a t h : 497-504. 1942. 61 V i n c e n t , J . M . The e s t e r s o f 4 h y d r o p y - b e n z o i c a c i d a n d r e l a t e d compounds . P a r t 1. M e t h o d s f o r t h e s t u d y o f t h e i r f u n g i s t a t i c p r o p e r t i e s . J o u r . S o c . Chem. I n d u s t r y , 66: 149-155. 1947. 

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