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The thermal decomposition of dimethyl acetal by the flow-tube method. II. A study of the abstraction… Lips, Alair 1940

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L lf^> A?.  I,  fix.  THE THERMAL DECOMPOSITION OF DIMETHYL ACETAL BY THE ' FLOW-TUBE METHOD  ..•II.  A STUDY OF THE ABSTRACTION OF POTASSIUM ETHYL XANTHATE FROM SOLUTION BY PURE LEAD SULFIDE •  Alair  Lips  A Thesis submitted in partial  fulfilment of  the requirements f o r t h e DEGREE OF MASTER OF ARTS i n t h e Department of Chemistry  A p r i l , 1940  V a n c o u v e r , B.C.  -I  *  ACKNOWLEDGEMENT Sincere appreciation t o Dr. W i l l i a m U r e f o r h i s gene r o u s h e l p and e v e r r e a d y  coun-  s e l throughout the course o f the investigation.  CONTENTS Page Purpose o f the I n v e s t i g a t i o n  1  Apparatus  2  Experimental Procedure  4  Materials  5  Determination of  Products  (a)  Qualitative  7  (b)  Quantitative  9  I n t e r p r e t a t i o n of Tables  13  Discussion  14  of Results  Bibliography  16  Tables  18  THB THERMAL DECOMPOSITION OF DIMETHYL AQSTjX •1.  PURPOSE 0 ? THE  INVESTIGATION  T h i s work was a t t e m p t e d  i n o r d e r t o supplement r e a c t i o n  r a t e d a t a o b t a i n e d i n t h i s l a b o r a t o r y b y W. G. P i e r c e  8  and  20 G. H. T u r n e r al.  on t h e t h e r m a l d e c o m p o s i t i o n o f d i m e t h y l a c e t -  I t was d e s i r e d t o d e t e r m i n e  t h e n a t u r e and t h e r e l a t i v e  amounts o f t h e p r o d u c t s o b t a i n e d b y t h e p y r o l y s i s o f t h i s substance.  T h i s i n f o r m a t i o n w o u l d be u s e f u l i n d e c i d i n g t h e  t y p e o f c h e m i c a l r e a c t i o n t o which t h e p a r t i c u l a r breakdown belongs* In in  t h e above i n v e s t i g a t i o n s , t h e p r o d u c t s were o b t a i n e d  s o s m a l l a q u a n t i t y as t o make e s t i m a t i o n o f t h e c o n s t i t u -  ents d i f f i c u l t .  I t was f e l t  t h a t w i t h the f l o w o r h o t tube  method o f d e c o m p o s i t i o n * l a r g e enough q u a n t i t i e s o f m a t e r i a l c o u l d be u s e d t o e n s u r e products.  a p p r e c i a b l e amounts o f t h e v a r i o u s  A l s o , b y a d j u s t i n g t h e r a t e o f f l o w and t h e t e m p e r  a t u r e o f t h e h o t t u b e , the p r i m a r y breakdown s u b s t a n c e s be s e c u r e d w i t h o u t c o n t a m i n a t i o n r e s u l t i n g f r o m t h e i r sive  could  progres  decomposition. R An a r t i c l e by a F r e n c h worker  was t h o u g h t  to provide  some c l u e a s t o t h e p o s s i b l e n a t u r e o f t h e r e a c t i o n * worker  f o u n d t h a t a t 400°, i n t h e p r e s e n c e  d i m e t h y l a o e t a l was l a r g e l y d i s i n t e g r a t e d and m e t h y l v i n y l e t h e r . o  This  of certain oxides, to methyl  alcohol  S i n c e t h e a l c o h o l i s n o t f u r t h e r de-  6  composed b e l o w 900  , i t s d e t e r m i n a t i o n would r e v e a l t h e ex-  t e n t t o w h i c h t h e b r e a k d o w n h a d o c o u r r e d , and t h e e t h e r , a  o 7 gas a t room t e m p e r a t u r e (B.P. 12-14 t e c t because  of i t s unsaturation.  p r o d u c t s m i g h t be formed u n d e r 2i  ) , w o u l d be e a s y t o deI t was. e x p e c t e d t h a t t h e s e  the i n f l u e n c e o f heat a l o n e .  APPARATUS, The r u n s were c a r r i e d o u t i n t h e a p p a r a t u s shown i n  Fig.  1. C  g  i s the detachable s t a r t i n g b u l b .  The  s e a l e d - i n tube  at the top prevents vapors from l i q u i d i n the bulb from ing  to d i r e c t c o n t a c t w i t h the grease of the ground  ris-  glass  . j o i n t , and t h e s m a l l o r i f i c e s l o w s up t h e e s c a p e o f v a p o r s d u r i n g t h e r u n o r w h i l e a w e i g h i n g i s b e i n g made. first  s e v e n r u n s , a s i m p l e s t a r t i n g b u l b was  For the  s e a l e d on f o r  each experiment* The r e m o v a b l e Run #8, C  s  and  c o n d e n s e r t u b e C2 was  also introduced  to f a c i l i t a t e removal o f l i q u i d products. s p e e d e d up o p e r a t i o n s c o n s i d e r a b l y *  g l a s s j o i n t s gave no t r o u b l e , and t h e r e was the  g r e a s e ( A p i e z o n M)  was  The use o f  The  ground  no e v i d e n c e t h a t  a t t a k e d by v a p o r s *  C i and C2 a r e c o n d e n s e r s * the  with  I n the e a r l i e r d e t e r m i n a t i o n s ,  l i q u i d p r o d u c t s were, c a u g h t i n b u l b s a t t h e b o t t o m s  of  t h e s e t r a p s * and were t h e n b r o k e n o r s e a l e d o f f . The  c y l i n d r i c a l b u l b B^ i s h e a t e d b y t h e e l e c t r i c  resist-  ance f u r n a c e F, whose t e m p e r a t u r e . i s m a i n t a i n e d a t any  desired  v a l u e b y means o f a p h o t o - e l e c t r i c s e t - u p .  This  arrangement  1  was u s e d by P i e r c e , and i s d e s c r i b e d i n h i s t h e s i s * p l a t i n u m e l e c t r i c r e s i s t a n c e thermometer. aluminum f o i l t o ensure u n i f o r m h e a t i n g *  T i s a-  B-^ j _ c o v e r e d w i t h s  5 Y i s .a d o u b l e m e r c u r y  v a l v e , by means o f w h i c h p a r t o f  the  a p p a r a t u s c a n be s e g r e g a t e d i f n e c e s s a r y .  ion  i s s u c h t h a t m e r c u r y w i l l n o t be pushed  or  The  construct-  i n t o the f u r n a c e  t h e c o n d e n s e r s i f a i r i s a c c i d e n t a l l y a d m i t t e d t o t h e ap-  paratus or i f a break o c c u r s . B-^ and Bg a r e gas s t o r a g e b u l b s .  M i s an .open m e r c u r y  c o n t a i n e r — a s a f e t y - v a l v e w h i c h p e r m i t s gas  to escape i f the  p r e s s u r e i n s i d e t h e a p p a r a t u s s h o u l d e x c e e d one The' h e i g h t o f t h e m e r c u r y  atmosphere.  dolumn h e r e forms a c o n v e n i e n t mea-  s u r e o f t h e gas p r e s s u r e . A i r may  be a d m i t t e d t h r o u g h t h e d r y i n g t u b e D and  stop-  c o c k Sg. T h i s f l o w - t u b e s e t - u p i s j o i n e d t o t h e m a i n vacuum l i n e 2 of  t h e a p p a r a t u s u s e d b y C.B.  Shipton  in  detail. The a r r a n g e m e n t  f o r t h e i o d i n e a d s o r p t i o n work  on gaseous  employed  and d e s c r i b e d by h i m  p r o d u c t s i s e s s e n t i a l l y t h a t w h i c h was  studied  3  "  Shipton , ing  by  The  volume o f t h e gas b u r r e t t e was  c h e c k e d by  t h e amount o f m e r c u r y i t c o u l d c o n t a i n , and was  agree c l o s e l y w i t h h i s v a l u e of 35cc.  weigh-  found to  T h i s f i g u r e was  used  i n t h e c a l c u l a t i o n o f t h e volume o f the f l o w - t u b e a p p a r a t u s ( o b t a i n e d by measurement o f t h e volume o f gas w h i c h a known d r o p i n t h e s a f e t y gauge Sg) t u b e was  produced  A m o d i f i e d Thunberg  a d o p t e d as an a d s o r p t i o n p i p e t t e s i n c e t h e l a r g e  ground g l a s s s t o p p e r p e r m i t t e d e a s y r e n e w a l of the reagent ready cleaning*  O t h e r gas a n a l y s i s were p e r f o r m e d w i t h a  s t a n d a r d Hempel o u t f i t A  and  4 5.  EXPERIMENTAL PROCEDURE I n m a k i n g a r u n t h i s p r o c e d u r e was C  wire  was  s  cleaned,  and  w e i g h e d by s u s p e n s i o n i n a l o o p  f r o m t h e arom o f t h e b a l a n c e .  dimethyl  a c e t a l was  followed  introduced  Then, f r e s h l y d i s t i l l e d  i n t o t h e b u l b by means o f  dropper with a long f i n e t i p u n t i l  the  been a d d e d .  replaced  out  The  delay,  s t a r t i n g t u b e was  to avoid  d e s i r e d weight on t h e  l o s s by v a p o r i z a t i o n , and  COg).  The  a p p a r a t u s was  guage showed a p r e s s u r e  o f 1.8  now  had  frame  withwith  instances,  evacuated u n t i l  x 10"^cm o r  a  surrounded  a Dewar f l a s k c o n t a i n i n g l i q u i d a i r ( o r , i n a few solid  of  the McLeod  less.  I n t h e q u a l i t a t i v e w o r k , a t t h i s s t a g e t h e Dewar was moved, and before  any  contained  r e p l a c i n g the  terminations,  allowed  c o o l i n g agent.  t h i s was  t o d e t e r m i n e any  gas  not  to b o i l For  out  acetal  the q u a n t i t a t i v e  done, s i n c e i t was  there  p o s s i b l e l o s s by v a p o r i z a t i o n .  t h e amount o f a i r i n t h e  of the  re-  de-  desired  I n any  case,  f r e s h l y d i s t i l l e d s u b s t a n c e was  neg-  ligible. Meanwhile, the e r a t u r e , and  f u r n a c e was  brought t o the  k e p t i n t h a t s t a t e by p r o p e r a d j u s t m e n t o f  photo-electric oontrol.  S t o p c o c k S4  i n t h e p o s i t i o n shown i n F i g u r e m a i n i n g i n t h e Dewar on G eately replaced a i r was  put  on  furnace.  g  was  1,  , and  was Now,  c l o s e d , and the l i q u i d  r e m o v e d , and  around the tube.  c o n d e n s a t i o n i n C^, the  desired  the  the  Sj_ p l a c e d a i r re-  f l a s k immed-  Another container  of  t h u s by s l o w v a p o r i z a t i o n i n G  t h e a c e t a l was  temp-  induced to flow  g  liquid and  through  O t h e r a t t e m p t s t o c o n t r o l the r a t e o f p a s s a g e  by  5  were made by s u r r o u n d i n g C  g  w i t h s o l i d C0  g  o r i c e and s a l t  a f t e r t h e l i q u i d a i r had been removed. The m a t e r i a l c a u g h t  i n t h e b o t t o m b u l b o f Gj_ was s e a l e d  o f f , o r was t r a n s f e r r e d t o d e t a c h a b l e Gg by means o f l i q u i d air.  Before removing  any l i q u i d s f r o m t h e a p p a r a t u s by s e a l -  i n g o r o t h e r w i s e , t h e y were a l l o w e d t o r i s e t o a known e r a t u r e , and t h e f u r n a c e was b r o u g h t blowing a i r through i t .  temp-  t o room t e m p e r a t u r e  S t o p c o c k Sg was t h e n c l o s e d ,  by  thus  s e p a r a t i n g a p o r t i o n o f g a s , c o l l e c t e d a t a known p r e s s u r e and  temperature, f o r a n a l y s i s . The n e x t s t e p was t o a d m i t a i r t h r o u g h S g .  Cg was r e -  moved f r o m t h e tube by means o f a d r o p p e r , and G again. 4. (i)  g  was w e i g h e d  The p r o d u c t s were r e a d y f o r v a r i o u s d e t e r m i n a t i o n s .  MATERIALS D i m e t h y l a c e t a l was p r e p a r e d f r o m m e t h y l a l c o h o l and  a c e t a l d e h y d e a c c o r d i n g t o t h e method o f A d k i n s and M s sen . I t was washed w i t h s a t u r a t e d c a l c i u m c h l o r i d e u t i o n t o remove m e t h y l a l c o h o l , and f r e e d f r o m by r e p e a t e d f r a c t i o n a l d i s t i l l a t i o n carbonate.  (neutral)  sol-  acetaldehyde  from anhydrous  potassium  The m a t e r i a l t h u s o b t a i n e d was a l l o w e d t o s t a n d  over m e t a l l i c  s o d i u m , and r e d i s t i l l e d  p o i n t from potassium carbonate  to constant b o i l i n g  just before using.  The p u r i t y  o f t h e p r o d u c t was c h e c k e d by r e f r a c t i v e i n d e x d e t e r m i n a t i o n s • a withApulfrich refractometer. D e s p i t e r e p e a t e d p u r i f i c a t i o n s , the a c e t a l , was p r e p a r e d i n c o l l a b o r a t i o n w i t h G.H.  Turner of t h i s  o r a t o r y , gave a v a l u e f o r t h e r e f r a c t i v e i n d e x  (average  which lab-  n-Q z 1,36585 w h i c h was d i f f e r e n t f r o m t h a t o f P i e r c e from t h a t o f another worker  .  d e n s i t y o f d i m e t h y l a c e t a l as  G.H.  7  Turner determined the  D S3 = ,8479 and D 25 4  hut. t h e s e f i g u r e s and f o u r o t h e r s ,  and  = ,8456,  4 8  >  15  »  1 6  17  > ,  when r e d u c e d t o  a common t e m p e r a t u r e , a l l d i s a g r e e d . I n o r d e r t o check the p r o p e r t i e s o f the d i m e t h y l a c e t a l , T u r n e r and t h e a u t h o r a t t e m p t e d t o p r e p a r e t h e s u b s t a n c e b y a n o t h e r method  , i n v o l v i n g the use o f a boron o x i d e c a t a l y s t ;  b u t u n f o r t u n a t e l y no y i e l d was' o b t a i n e d . v o l v i n g the use o f m e t a l l i c tempted, ing"^.  salts  9  O t h e r methods i n -  as c a t a l y s t s were n o t a t -  s i n c e d a t a i n r e g a r d t o t h e i r e f f i c a c y was Other c a t a l y t i c p r o c e d u r e s ^ '  o f hydrogen  conflict-  ' i n v o l v i n g the use  c h l o r i d e gas, hydrochloric a c i d , or g l a c i a l  acetic  a c i d t o e f f e c t t h e c o m b i n a t i o n o f a l c o h o l and a l d e h y d e t o f o r m d i e t h y l a c e t a l m i g h t have b e e n u s e d t o p r e p a r e t h e d i m e t h y l compound. A n a t t e m p t t o p r o v e t h e p u r i t y o f t h e a c e t a l by m o l e c u l a r 14 w e i g h t d e t e r m i n a t i o n b y t h e V i c t o r Meyer method  proved un-  s a t i s f a c t o r y , s i n c e t h e vapor d i s s o l v e d i n the water used t o measure i t s p r e s s u r e .  I t was p l a n n e d t o o b v i a t e t h i s  diffic-  u l t y b y an a d a p t a t i o n o f a method d e s c r i b e d b y N i e d e r l v o l v i n g t h e measurement o f m e r c u r y t h e s u b s t a n c e t o be d e t e r m i n e d .  , in-•  d i s p l a c e d by the vapor o f  An a p p a r a t u s was  specially  made f o r t h i s p u r p o s e , b u t t h e m o l e c u l a r w e i g h t o f pure a l c o h o l c o u l d n o t be f o u n d w i t h i n Zfo o f e r r o r .  I t was  methyl seen  t h a t t h e l i m i t o f e x p e r i m e n t a l e r r o r h e r e was g r e a t e r t h a n i n t h e measurement o f r e f r a c t i v e i n d e x , s o t h e work was  discon-  7 ..tinned. Every p o r t i o n o f p u r i f i e d dimethyl a c e t a l continued to show c o n s t a n t p r o p e r t i e s , so i t was  d e c i d e d t o go ahead w i t h  t h e i n v e s t i g a t i o n , s i n c e t h e s u b s t a n c e was eous .  However, i t was  noted that exposure t o m o i s t a i r f o r  any l e n g t h o f t i m e p r o d u c e d  a v e r y s l i g h t b u t d e t e c t a b l y de-  c o m p o s i t i o n of the m a t e r i a l , HgC0 .  For t h i s reason, only  3  f r e s h l y p u r i f i e d p r o d u c t was (ii) .  e v i d e n t l y homogen-  used  throughout the r e s e a r c h .  Pure methyl a l c o h o l f o r t e s t purposes 5  from B a k e r s C P .  methanol.  for several  T h i s was  days and was  prepared  allowed to stand over  anhydrous  CaO  f r e s h CaO  u n t i l a c o n s t a n t b o i l i n g p o i n t was  ( i i i ) . ~ A c e t a l d e h y d e was  was  then d i s t i l l e d  from  attained.  p r e p a r e d from p a r a l d e h y d e 19  depolymerization with dilute sulphuric acid f i e d by r e p e a t e d f r a c t i o n a l d i s t i l l a t i o n .  , and was I t was  by  puri-  noticed  t h a t d i m e t h y l a c e t a l w h i c h had b e e n p r e p a r e d f r o m impure aldehyde  s m e l l e d s t r o n g l y o f c r o t o n a l d e h y d e , and t h a t  s u b s t a n c e was  difficult  t o remove c o m p l e t e l y by  acetthis  fractionation,  despite i t s high b o i l i n g point. Grotonaldehyde i s prepared by t h e a c t i o n o f c o l d , c o n c e n t r a t e d s u l p h u r i c a c i d upon p a r 21 aldehyde  , and  t h i s would account  for i t s s l i g h t formation  along with acetaldehyde. (iv) .  O t h e r c h e m i c a l s u s e d were B a k e r ' s C P .  stock or  f r o m E i m e r and Amend. 5.  ANALYTICAL  .(.a) QUALITATIVE (i)  B o i l i n g p o i n t s o f l i q u i d s were o b t a i n e d by  • S i w o b o l o f f * s method (ii)  22  8  .  L i q u i d s were t e s t e d f o r u n s a t u r a t i o n b y s h a k i n g i n  a glass-stoppered  b o t t l e with a carbon t e t r a c h l o r i d e s o l u t i o n  of i o d i n e . 23 (iii) metallic  A l c o h o l s were d e t e c t e d  by F e i g l ' s t e s t s  and by  sodium.  F e i g l ' s #1s f o r a n y common a l c o h o l , depends on t h e e s t e r i f i c a t i o n o f the a l c o h o l and t h e f o r m a t i o n by the e s t e r o f a- c h a r a c t e r i s t i c a l l y - c o l o r e d i r o n s a l t . r e f l u x was c o n s t r u c t e d  for this  F e i g l ' s #2 f o r p r i m a r y  An a l l - g l a s s  micro-  determination.  and s e c o n d a r y a l c o h o l s i s b a s e d  upon t h e i r c o n v e r s i o n b y c a r b o n d i s u l p h i d e and s o d i u m h y droxide  t o a l k a l i xanthogenates which y i e l d a c h a r a c t e r i s t i c  c o l o r r e a c t i o n with molybdates. u s e d h e r e t o do away w i t h c o r k  Glass  stoppered  t u b e s were  contamination.  B o t h F e i g l ' s #1 and #2 were p e r f o r m e d w i t h p u r e a l c o h o l and pure a c e t a l d e h y d e , i n these  a n d were f o u n d t o g i v e no t e s t  instances.  Metallic but  dimethyl  s o d i u m p r o d u c e s no r e a c t i o n w i t h d i m e t h y l  acetal  i f methyl a l c o h o l i s p r e s e n t , bubbles o f hydrogen are  formed, and in. a d d i t i o n a y e l l o w s o l i d  compound a p p e a r s .  l a t t e r s u b s t a n c e seems t o be a p o l y m e r o f t h e a c e t a l , by t h e a c t i o n o f s o d i u m m e t h y l a t e on t h a t compound.  This  formed This  w o u l d be a n a l o g o u s t o t h e p o l y m e r i z a t i o n o f a c e t a l d e h y d e b y 24 NaOH, and w o u l d be i n l i n e w i t h t h e s t a t e m e n t b y B e r n t h s e n 1  t h a t a c e t a l s undergo aldehyde p o l y m e r i z a t i o n . hyde i s p r e s e n t  i n the a c e t a l - a l c o h o l mixture  I f acetaldethat too i s  polymerized. (iv)  A l d e h y d e s were t e s t e d f o r b y t h e u s e o f NaOK and  Tollen's  reagent"^,  Acetaldehyde,  when h e a t e d w i t h NaOH, f o r m s a y e l l o w  pol-  ymer. T o l l e n ' s ammoniaca1 s i l v e r n i t r a t e s o l u t i o n i s much more s e n s i t i v e , and p r e c i p i t a t e s o u t b l a c k m e t a l l i c s i l v e r when reduced by t r a c e s o f any a l d e h y d e . Another t e s t , i n v o l v i n g the r e d u c t i o n of f u c h s i n OUB a c i d  1 5  , was a l s o  st d U  l e  sulphur-  d.  T h e s e t h r e e p r o c e d u r e s were b l a n k - t e s t e d w i t h m e t h y l a l c o h o l and d i m e t h y l (v) .  a c e t a l , and were f o u n d t o be  Gaseous p r o d u c t s  satisfactory.  were w i t h d r a w n f r o m t h e a p p a r a t u s  i n t o e v a c u a t e d b u l b s , and were s h a k e n w i t h p o t a s s i u m permang a n a t e s o l u t i o n , b r o m i n e w a t e r , and i o d i n e i n c a r b o n  tetra-  chloride to test f o r unsaturation. (b)  QUANTITATIVE (i)  Preliminary  The q u a l i t a t i v e d a t a e s t a b l i s h e d t h e f a c t t h a t t h e l i q u i d i products hol  w o u l d c o n t a i n o n l y d i m e t h y l a c e t a l and m e t h y l a l c o -  under normal circumstances.  substances,  or the determination  The s e p a r a t i o n o f t h e s e  o f one i n t h e p r e s e n c e o f  the o t h e r , c o n s t i t u t e d a d i f f i c u l t problem. properties  '  Their physioal  , are s i m i l a r ; t h e i r b o i l i n g p o i n t s are p r a c t -  i c a l l y i d e n t i c a l , and t h e i r ' d e n s i t i e s and r e f r a c t i v e are very c l o s e .  two  indices  T h e y a r e b o t h s o l u b l e i n a l l t h e common  10 solvents. C h e m i c a l methods w h i c h w o u l d remove m e t h y l a l c o h o l i n v o l v e t h e use o f m i n e r a l a c i d s o r s t r o n g o x i d i z i n g  agents  which would h y d r o l y s e o r d e s t r o y the d i m e t h y l a c e t a l .  Sub-  26 s t n a c e s s u c h a s 2, 4 d i n i t r o b e n z o y l c h l o r i d e  which  precip-  i t a t e s m e t h y l a l c o h o l , cannot be u s e d , s i n c e i n m o i s t a i r t h e y would h y d r o l y s e t o form s m a l l q u a n t i t i e s o f m i n e r a l a c i d s . 27 S i m i l a r l y , P r e g l * s method o f d e t e r m i n i n g methoxy groups m i g h t be u s e d t o measure t h e r e s i d u a l d i m e t h y l a c e t a l i f t h a t s u b s t a n c e were n o t h y d r o l y s e d by t h e h y d r i o d i c a c i d u s e d i n the  process. (ii)  The f i r s t method o f e s t i m a t i o n d e v i s e d f o r m e t h y l  a l c o h o l was a n a d a p t a t i o n o f a q u a l i t a t i v e t e s t f o r a c e t a l 25 dehyde  .  P r e p a r e d m i x t u r e s o f a l c o h o l and a c e t a l were r e -  f l u x e d w i t h d i l u t e IIC1 i n an a l l g l a s s a p p a r a t u s ; t h e r e s u l t ing  a c e t a l d e h y d e was p r e c i p i t a t e d by 2*. 4 d i n i t r ophe n y l h y dr a -  z i n e as t h e h y d r a z o n e , and t h i s p r e c i p i t a t e was p u r i f i e d and weighed.  The r e s u l t s o b t a i n e d f r o m two s u c h d e t e r m i n a t i o n s  were i n f a i r l y c l o s e a g r e e m e n t (1,2%), b u t t h e p r o c e s s was f o u n d t o be  time-consuming.  The u s e o f m e t a l l i c s o d i u m was n e x t i n v e s t i g a t e d . f e r r i n g b a c k t o F i g . 1, a r u n (#10)  was c o m p l e t e d i n t h e u s u a l '  manner, b u t t h e l i q u i d p r o d u c t s were k e p t i n C^. moved , p a r t i a l l y f i l l e d  Cg was r e -  w i t h f r e s h l y c u t s o d i u m , and r e p l a c e d .  C^ was t h e n s u r r o u n d e d w i t h l i q u i d a i r , acuated.  Re-  The p r o d u c t s were d i s t i l l e d  and t h e a p p a r a t u s e v -  o v e r i n t o C2, and t h i s  t r a p was c o o l e d w i t h i c e - w a t e r t o p r e v e n t t h e h e a t o f s o d i u m  11 r e a c t i o n from v a p o r i z i n g the l i q u i d s .  When t h e a c t i o n was  c o m p l e t e , a Dewar o f l i q u i d a i r was p l a c e d about t h e c o n d e n s e r and h y d r o g e n pumped o f f and m e a s u r e d * This procedure The  was f o u n d  to possess  c e r t a i n drawbacks.  r e a c t i o n w i t h s o d i u m c o n t i n u e d i n d e f i n i t e l y , and i t was  i m p o s s i b l e t o a s c e r t a i n when e v o l u t i o n o f h y d r o g e n h a d c e a s e d . I n a d d i t i o n t o t h i s , t h e d i m e t h y l a c e t a l formed a y e l l o w p o l ymer w h i c h methylate  c o a t e d t h e s o d i u m and impeded t h e a c t i o n . i s l i s t e d a s p o s s e s s i n g two m o l e c u l e s  cohol of c r y s t a l l i z a t i o n formed.  o f methyl a l -  , so a l l t h e OHgOH may n o t be t r a n s -  .  The  u s e o f the r e f r a c t o m e t e r i n the p u r i f i c a t i o n o f d i -  methyl a c e t a l suggested cohol.  Sodium  The r e f r a c t i v e  a n o t h e r method o f d e t e r m i n i n g t h e a l index of the l i q u i d product, since i t  c o n s i s t e d o f o n l y two s u b s t a n c e s , s h o u l d f u r n i s h i n f o r m a t i o n about t h e i r r e s p e c t i v e p r o p o r t i o n s , even i f t h e r e l a t i o n s h i p between r e f r a c t i v e  i n d e x and c o m p o s i t i o n i s n o t a l i n e a r o n e .  A s e r i e s o f standard mixtures o f methyl  a l c o h o l and d i -  m e t h y l a c e t a l was made u p , and t h e i r r e f r a c t i v e i n d i c e s measured*  These m i x t u r e s were p r e p a r e d  from f r e s h l y  distilled  m a t e r i a l s , were w e i g h e d i n g l a s s - t o p p e d b o t t l e s , and were d e termined immediately* graph, percentages  R e s u l t s were g r a p h e d ,  n ^ ~*.  this  i n unknowns were r e a d , k n o w i n g t h e r e f r a c -  1^.5 t i v e index,  and f r o m  25 and n  D  f o r m e t h y l a l c o h o l were f o u n d t o be  1.35114 a n d 1.32759 r e s p e c t i v e l y , c h e c k i n g c l o s e l y w i t h t h e l i s t e d values  o f 1,33118 and 1.32761.  I I  12 (iii)„ The e s t i m a t i o n o f v i n y l , m e t h y l e t h e r was 5  by t h e work o f C h a l m e r s , who o b s e r v e d v i o l e n t l y with iodine , forming polymer.  t h a t the ether  suggested reaots  a highly-viscous pitch-black  The a c t i o n i s s p o n t a n e o u s , and a p p a r e n t l y a v e r y  small q u a n t i t y of iodine w i l l The  gaseous p r o d u c t s  tact with elemental  e f f e c t the polymerization.  f r o m o u r r e a c t i o n were p u t i n c o n -  i o d i n e i n an a d s o r p t i o n p i p e t t e , a n d an  i d e r i t i c a l phenomenon o c c u r r e d .  Pure p r e p a r a t i o n s of d i m e t h y l  a c e t a l , m e t h y l a l c o h o l , and a c e t a l d e h y d e s u b j e c t e d t o t h e same t e s t . m e r i z a t i o n , forming  were v a p o r i z e d and  They p r o d u c e d no s i g n s o f p o l y -  only a s l i g h t  brown s t a i n on t h e w a l l s o f  t h e a b s o r p t i o n p i p e t t e . ' T h i s was caused' by a p a r t i a l o f t h e i o d i n e by t h e c o n c e n t r a t e d  vapors,  l e a v i n g the i o d i n e very  f i n e l y d i v i d e d when t h e p i p e t t e was pumped o u t . None o f t h e s e three substances  s u f f e r e d any m e a s u r a b l e l o s s i n v o l u m e ,  whereas t h e g a s e o u s m i x t u r e i a b l y diminished. when t h e m i x t u r e  c o n t a i n i n g t h e e t h e r was  apprec-  T h e r e was no f u r t h e r d e c r e a s e i n volume was p l a c e d i n c o n t a c t w i t h f r e s h  reagent,  p r o v i n g t h a t t h e r e m o v a l o f m e t h y l v i n y l e t h e r h a d been complete. In  p r a c t i c e , t h e f r e s h l y f i l l e d a d s o r p t i o n p i p e t t e was  evacuated  while surrounded w i t h s o l i d C 0 . g  o f t h e i o d i n e i s so s l i g h t not a f f e c t t h e a c c u r a c y this error i s diminished  The v a p o r  (.202mm a t 20 0)  o f the determinations  pressure  that i t should a p p r e c i a b l y , and  by r e a c t i o n o f t h e g a s e o u s i o d i n e  w i t h t h e m e r c u r y i n t h e T o p l e r pump. been pumped o u t , t h e r e a g e n t  A f t e r t h e p i p e t t e had  was i n d u c e d  by g e n t l e h e a t i n g t o  c o v e r most o f t h e i n s i d e s u r f a c e o f t h e t u b e w i t h a f i n e of  layer  crystals. The method o f e s t i m a t i n g t h e e t h e r l e f t  something  d e s i r e d , s i n c e the r e a c t i o n between t h e i o d i n e vapor  t o be  and t h e  m e r c u r y f o r m e d an u n d e s i r a b l e c o a t i n g on t h e i n s i d e of t h e T o p i e r pump.  I n a d d i t i o n , t h e i o d i n e vapor adsorbed  cock g r e a s e and n e c e s s i t a t e d i t s f r e q u e n t (iv)  renewal.  G o n d e n s i b i l i t y o f t h e gaseous r e a c t i o n  was a s c e r t a i n e d b y m e a s u r i n g  on s t o p -  products  the f r a c t i o n o f the m a t e r i a l  t h a t w o u l d c o n d e n s e o u t i n t h e a d s o r p t i o n p i p e t t e when i t was surrounded 6.,  with solid  INTERPRETATION (i)  COg.  OF THE  TABLES  The p o s i t i v e t e s t s f o r a l d e h y d e  i n r u n s #1 and #3  i n d i c a t e I n s u f f i c i e n t p u r i f i c a t i o n o f the s t a r t i n g  material.  The l i q u i d p r o d u c t s were a l l o w e d t o assume room tempera t u r e before removal  from  the a p p a r a t u s , t h u s a l l o w i n g any  d i s s o l v e d methyl v i n y l ether to escape.  Hence t h e s e  substan-  c e s d i d n o t e x h i b i t a n y u n s a t u r a t e on. • ( i i ) The t a b l e s p r e s e n t o n l y t h e p e r c e n t o f m e t h y l a l c o h o l i n t h e l i q u i d p r o d u c t s , so t h i s f i g u r e s h o u l d be  slight-  l y l o w e r t h a n t'he v a l u e o b t a i n e d f o r t h e e t h e r , i f t h e two a r e formed i n e q u a l q u a n t i t i e s .  This i s found t o h o l d w e l l f o r  t h e c a s e s where t h e l i q u i d s a r e r a i s e d t o room and e x t e n s i v e v a p o r i z a t i o n  temperature,  occured.  The t o t a l volume o f gas i s s e e n  t o be f a i r l y  constant,  and t o depend n o t on t h e amount o f a c e t a l u s e d , b u t upon t h e temperature  t o ' w h i c h t h e l i q u i d p r o d u c t was r a i s e d and t h e  14 amount o f permanent gas p r e s e n t .  C a l c u l a t i o n reveals that i f  t h e gas i s c o n s i d e r e d , as d i m e t h y l a c e t a l v a p o r , i t s weight p r o x i m a t e s t h e d i f f e r e n c e s i n w e i g h t l i s t e d i n T a b l e 5,  ap-  since  i n no e a s e d i d e x t e n s i v e d e c o m p o s i t i o n o f the s t a r t i n g m a t e r i a l "occur. The  time o f t h e r u n c o u l d n o t be d e t e r m i n e d e x a c t l y ,  since  t h e a c e t a l d i d n o t go t h r o u g h t h e f u r n a c e a t a u n i f o r m r a t e . When a p o r t i o n o f m a t e r i a l h a d l e f t  the s t a r t i n g b u l b , t h i s  c o o l e d t h e r e s i d u a l l i q u i d , so t h a t v a p o r i z a t i o n s t a t i o n a r y f o r varying lengths of time.  remained  Thus t h e f i g u r e s  ob-  t a i n e d are not very s i g n i f i c a n t  e x c e p t i n s o f a r as t h e y r o u g h l y  i n d i c a t e t h a t a l o n g e r exposure  t o heat u s u a l l y produced g r e a t -  er decomposition^  7.  DISCUSSION OF RESULTS (i)  The  qualitative information strongly indicates  the thermal d e c o m p o s i t i o n o f d i m e t h y l a c e t a l i s a s i m p l e i n t o m e t h y l a l c o h o l and m e t h y l v i n y l e t h e r .  T h i s may  that split  be com-  p l i c a t e d by t h e f u r t h e r d e c o m p o s i t i o n o f t h e e t h e r t o y i e l d permanent g a s e s , and by s l i g h t h y d r o l y s i s o f t h e a c e t a l i f t h e m a t e r i a l i s exposed 64-66° b o i l i n g r a n g e  t o m o i s t a i r f o r any l e n g t h o f t i m e . o f the l i q u i d p r o d u c t , the r e s u l t s  t h e a l c o h o l and a l d e h y d e  t e s t s , and  The of  the u n s a t u r a t i o n o f the  gas b u t n o t o f t h e l i q u i d do n o t seem t o p e r m i t any o t h e r p o s sibility. (ii)  On the...quantitative- s i d e , t h e e v i d e n c e f o r e q u a l  p r o p o r t i o n s o f m e t h y l a l c o h o l and m e t h y l v i n y l e t h e r i n t h e breakdown p r o d u c t i s f a i r l y c e r t a i n .  However, h e r e t h e a c -  curacy  of the r e s u l t s i s l i m i t e d by c e r t a i n f a c t o r s .  l i q u i d product  i s n o t r a i s e d t o room t e m p e r a t u r e , some m e t h y l  v i n y l e t h e r may r e m a i n d i s s o l v e d .  This w i l l  affect the iodine  a n a l y s i s , but s h o u l d not d i s t u r b the r e f r a c t i v e i n d e x mination ling to  15 When t h e  deter-  s i n c e t h e e t h e r w i l l r a p i d l y e s c a p e d u r i n g t h e hand-  i n t h e l a t t e r measurement.  I f the products  room-temperature before withdrawal  are r a i s e d  from the apparatus,  much o f t h e m a t e r i a l w i l l v a p o r i z e , and t h e p r o p o r t i o n s o f a l c o h o l and a c e t a l may be d i f f e r e n t i n the l i q u i d phase.  i n t h e gas p h a s e f r o m  However, t h e amounts o f a l c o h o l and  e t h e r a r e of t h e same o r d e r e x c e p t i n t h o s e manent g a s was (iii) composition  those  c a s e s where  per-  formedi  I t i s e v i d e n t , t h a t t h e optimum c o n d i t i o n s f o r d e were n e v e r a t t a i n e d .  O n l y i n a few i n s t a n c e s  where l a r g e q u a n t i t i e s o f t h e a c e t a l were u s e d , d i d p a r t o f t h i s m a t e r i a l happen t o p a s s t h r o u g h t h e f u r n a c e t o produce e x t e n s i v e  s l o w l y enough  d e c o m p o s i t i o n > and t h e f l o w o f t h i s  t i o n was s o s l o w t h a t p r o g r e s s i v e b r e a k d o w n o c c u r r e d . w o u l d seem t h a t t h e d i s i n t e g r a t i o n w i l l 300-500°j a l t h o u g h  por-  It  o c c u r anywhere b e t w e e n  the temperature a t which the r e a c t i o n be-  g i n s was n o t a s c e r t a i n e d . For  f u r t h e r study  on t h i s s u b j e c t , a s u i t a b l e means o f  m e a s u r i n g and c o n t r o l l i n g t h e f l o w o f m a t e r i a l s t h r o u g h the furnace.should wool should  be d e v e l o p e d .  Packing  t h e f l o w tube w i t h  glass  d i m i n i s h t h e r a t e o f p a s s a g e , and w o u l d r e v e a l t h e  effect of increased  s u r f a c e upon t h e e x t e n t o f  decomposition.  16  BIBLIOGRAPHY I.  W. G. P i e r c e ,  T h e s i s , 1939*  2*  G. B., S h i p t o n ,  T h e s i s , 1939.  3.  G. B. S h i p t o n ,  T h e s i s , 1937.  4*  M. Gabanac,  5.  Beilstein,  6.  ¥. C h a l m e r s ,  7.  Organic Syntheses,  8*  H i n t o n and N i e w l a n d ,  9.  C. A.,  Compt. Rend.,  190 , 881,-1930. :  1, 2 7 6 , 1918. Can. J o u r . R e s . ,  7, 472, 1932.  3, 1, 1 9 2 3 . J.A.C.S. , 5 2 , 2 8 9 2 , 1 9 3 0 .  1 1 , 8 6 , 1917.  10.  J . A. G. S., 4 4 , 2 7 4 9 , 1 9 2 2 .  II.  Ann*,  1 2 6 , 62, 1 8 6 2 .  12.  Ber.,  3 0 , 3 0 5 3 , 1897,  13.  Sabatier,  C a t a l y s i s i n Organic  14.  Sherrill,  Laboratory Experiments.  15.  Mullikan,  Identification  16.  Handbook o f C h e m i s t r y and P h y s i c s ,  17.  Beilstein,  18.  Niederland Niederi,  Chemistry.  o f P u r e O r g a n i c Compounds, V . I . 1939-40.  1, 9 2 1 , 1 8 9 3 . Organic Quantitative  Micro-analysis,  pge. 1 7 5 . 19*  McLeod,  Am.  Cham. J o u r . ,  20.  G. H. T u r n e r ,  21.  D e L i s l e , F o w l e r , Love11 & U r e ,  T h e s i s , 1940  Crotonaldehyde. 22.  Lassar-Cbhm,  23.  Geigl,  3 7 , 2 7 , 1907.  T h e r m a l Decomp. o f  T r a n s . R.S.C. , S e c t i o n 1 1 1 , 1936.  O r g a n i c L a b o r a t o r y M e t h o d s , pge. 365.  S p o t T e s t s , pge. 250.  17 24.  Bernthsen,  25.  Shriner  Organic Chemistry,  and F u s o n ,  pge. 136*  I d e n t i f i c a t i o n o f O r g a n i c Compounds,  p g e , 148. 26.  Melons & R e i d ,  27.  Pregl,  J.A.C.S. , 5 1 , 3 4 2 6 , 1929.  Quantitative  Organic M i c r o a n a l y s i s ,  pge. 1 8 1 .  18 TABLE I 'QUALITATIVE DETERM! NAT I ON OF PRODUCTS f.lun T [ — ~  I j , i n Na §01, ~  F e i g l ' s F e i g l ' s NaOH #1 "-  Tollens  20 nr>  Av. -B.P. ~ C~  Unsat. o f Gases  D  \fl j  360°  \$Z 360  no change t v e "  t  ve  Alkaline KHH0 lightened  + ve  tve  64.2  -ve  -ve  66.1 1.36360  -ve  ve  A  I \$3 360° I  "  ve  ve  ve  64.65  Color r e moved from I i n GC1  v  2  if4  360°  if*5  400°  ve "  ve  ve ve  ve  -ve  -ve  64.75  ve  -ve  -ve  64.90  A  Color r e moved f r o m Br water. g  TABLE; I I ANALYSIS OF PERMANENT GASES [tan  %Water Soluble 61.7  %Condensible by Ice.& Water  0  g  G0g  71.8  0  0  79.4  0  0  Comoosition o f Non-condensibles H i g h e r Ho- E t h y l e n e CO HHg CH, mologues o f ...Ethylene 0 8.8 41.2 12.6 35.8 1.4  14.9  37.5 17.8 27.2  If  TABLE I I I Run  Weight of Starting Material  6 • 14*0?  Wt. o f L i q u i d Product  Difference  n£  p&eOE f r o m Graph  13.637  .363  1.36624  2.9  7  9*868  9.480  .388  1.36430  8.6  8  2.847  2,569  © 2 79  1.36641  . 2.1  9  2.502  2«232  .270  10  2 .747  2.481  .266  11  3.930  3.671  e 2*59  12  3.264  2.978  .286  1.36598  4.0  13  2.807  2.545  •2 62  1.56623  2.9  14  3.029  2.695  .334  1.36616  3.3  15  5.347  5.009  .338  1.36617  3.3  16  4.093  3.740  o  353  1.36600  3.4  17  6.269  5.958  o  311  1*56624  2.9  18  4*672  4.326  .346  1*36630  2&7  19  5*189  4.857  1*36642  2.1  2.4 17.6cc;H * a t N.T.P. 1.36625  1.82 2*9  TABLE I T Run  Barom. P. S a f e t y P -P Guage P. P p B ^sg B  T A  T o t a l v o l . gas a t N.T.P. P - P g s 270 - v o l . o f V. B  S  =  J>  75.60  55  55  20.05  21.40  7  75.45  53.55  20.90  22.5  8  76.00  61i60  14.40  22 9 4:5  71.8  9  75.40  61.00  14.40  21.7  69.5  10  76.10  61.65  14.45  21 o 35  68.5  11  76.12  62.5  13.70  22 • 5  68.5  12  76.10  59  95  16.15  20.5  73.6  13  75.85  63.20  12.65  23.65  67,4  14  76.30  59.35  16.95  22.8  86.0  15  75.8  -58.9  16.9  ESiBS'  85.8  16  75.7  58.9  16.8  24.55  91.7  17  76.00  58.65.  17.35  23.5  88.8  18  76.05  58.20  17.85  22.0  89.0  19  76.10  58.85  17.25  21«8  89.1  •  ©  93.4 102.2  21  TABLE ¥ Pol Run  14.Gem P  l  P  p  6  31.20  19.45  7  19.25  16.60  8  18.25  17.25  9  27*3  24.4  10  35*65  31.60  11  29.70  23.90  12  18.9  16.6  13  29.3  24,55  14  3*J e  15  25 o6  19 • 3 5  16  22.5  19.85  17  23.40  18  18  23.05  19, 6  19  27.2  22 g 9  X  p  l~ 2 r — —  2  24:*  g -P 1  0  E x V x 58 22400 : Sample Wt.  l n f  X  .683  1.76 %  .503  2.01  9 235  2«20  •218  2«32  .187  1.80  .369  2.48  .457  3.98  .310  2,83  .311  3.41  o 5o*7  3o 33  ,582  3.31  e 54:2  2*96  .380 .  2.80  .327  2.17  55  c3  w - % Ether  1 0 0 / 0  22  TABLE Y I Run  Temt>, Time o ~ . hrs.  feOH  Either  foNon-oon-  Temp. Product Raised To °C  densibles of Y  0  T  LOSE  Wt.  6„  360  18  2«Q  1.76  7  360  18  8,6  2. 01  8  360  14  2.1  2.20  0  71.8  15  .279  9  360  12  2.4  2«32  0  69,5  15  .270  10  360  10  1.82  1.80  0  68.5  15  .266  1 1 •.'  360  15  2. 9  2.48  0  68,5  14.2  .259  12  340  15  4.0  3.98  1.97  73,6  15  .286  13  350  17  2.9  B. 83  .—  67.4  14.5  ^262  14  410  5  3 e3  3.41  0  86,0 . 19.5  .354  15  460  .4  3 #3  3 o 3o  1.12  85.8  19  .358  16  425  5  3.4  3.31  3.0  91.7  24.55 « 3 53  17  465  6  2.9  2.96  0  88.8  23  .511  18  360  10,5  2.7  2.80  0  89.0  25  .346  19  320  15  2o1  2.17  0  89.1  22.8  ft 332  93.4 25.17  -  15  .363  X 0 2 & 2 15  ,,388  TABLE V I I STANDARD REFRACTIVE INDICES Wt. o f A c e t a l  Wt. o f A l c o h o l  tfMe OH  n  20 D  0  1.36694  100  1.32919 1,36541  2.610  .176  2.164  .368  17.01  1.36192  1.945  .644  33.1  1.35532  1.782  1.005  56.4  1.34955  3.101  .040  1,28  1.56664  2.710  .276  9.25  1.36445  2.273  .559  3.377  .170  4. 78  1.56576  3.229.  .109  3 © 22  1.36606  3.006  .093  3.10  1.56620  2.912  .071  2.40  1.56637  6.74  19.76  1.36025  CONTENTS Page Introduction  .  1  Materials  S  Apparatus  3  Experimental Methods of S a n t h a t e D e t e r m i n a t i o n  3  T i t r a t i o n with Iodine  4  O t h e r T i t r a t i o n Methods  4  C o l o r i m e t r i c Methods  5  X a n t h a t e A b s t r a c t i o n and R e l a t e d Methods  6  Discussion  15  Bibliography  17  1  THE ABSTRACTION OF POTASSIUM ETHYL XANTHATS' FROM SOLUTION BY PURE LEAD SULPHIDE  INTRODUCTION When r e s e a r c h on f l o t a t i o n was begun i n t h i s ory,  t h e c h i e f p r o b l e m t o be a t t a c k e d  laborat-  was t h e q u e s t i o n o f  •what p r o p e r t y , c h e m i c a l o r p h y s i c a l , o f t h e c o l l e c t i n g a g e n t c a u s e d t h e m i n e r a l p a r t i c l e t o be f l o a t e d . that  I t was t h o u g h t  a s t u d y o f c o l l e c t o r a b s t r a c t i o n , by t h e m i n e r a l  from  s o l u t i o n might y i e l d  some c l u e  as t o the s t a t e o f a f f a i r s a t  the  and, with  that  p a r t i c l e surface  described rather  i n t h i s report  was done.  end i n v i e w , t h e work A pure prepared m i n e r a l  than a pure n a t u r a l l y - o c c u r r i n g  experiments, i n order that influenced  by i m p u r i t i e s  one was u s e d i n t h e  t h e o b s e r v e d r e s u l t s m i g h t n o t be  i n the substance.  A thorough review of f l o t a t i o n l i t e r a t u r e , that  on t h e t h e o r i e s 1  Bennett  including  o f c o l l e c t o r a c t i o n , h a s been made by  , and no a t t e m p t w i l l be made t o r e s t a t e any o f t h i s  material.  MATERIALS AND PREPARATIQMS P u r e P o t a s s i u m E t h y l Xantfaate l i t r a t e were p r e p a r e d a c c o r d i n g  and r e c r y s t a l l i z e d  lead  t o methods d e s c r i b e d b y  2  Pearce . Lead S u l p h i d e the  was p r o d u c e d f r o m P b ( N O g )  a c t i o n o f washed h y d r o g e n s u l p h i d e .  i t a t e was t r e a t e d w i t h d i s t i l l e d  g  s o l u t i o n by  The r e s u l t i n g p r e c i p -  w a t e r i n an e l u t r i a t o r  t h e wash l i q u i d gave no t e s t f o r l e a d i o n w i t h H S , g  its  o x i d a t i o n , PbS was s t o r e d u n d e r w a t e r u n t i l Starch  until  To p r e v e n t  required.  Indicator f o r Iodine-Xanthate.Titration  s t made f r o m s t a r c h a n d w a t e r o n l y , b u t a s o l u t i o n  was f i r -  containing  3 murcuric iodide  was f o u n d t o g i v e a s h a r p e r end-point,.  P r a c t i c a l l y a l l o f t h e c h e m i e a l s u s e d were B a k e r ' s 0. P.  stock. Some w o r k e r s p o s t u l a t e  xnathic  the formation  o f d i x a n t h o g e n and  a c i d from xanthate i n c e r t a i n f l o t a t i o n  The p r e p a r a t i o n  1  reactions .  o f t h e s e s u b s t a n c e s was a t t e m p t e d , i n o r d e r  t h a t some d e g r e e o f f a m i l i a r i t y w i t h them m i g h t be a t t a i n e d . 4 D i x a n t h o g e n was made as o u t l i n e d i n B e i l s t e i n  , and was f o u n d  •to be a n o i l y brown l i q u i d w h i c h d i d n o t c r y s t a l l i z e i n f o u r and  one-half  the  a c t i o n o f d i l u t e HOI on KEtX- a t 0° , b u t t h e r e s u l t was  uncertain.  months o f s t a n d i n g .  Xanthic 4  a c i d was p r e p a r e d b y  The p r o d u c t was f o u n d t o e x e r c i s e a r e d u c i n g aet^-  i o n upon KHnO^ s o l u t i o n * i n d i c a t i n g " t h a t i t w o u l d be t i t r a t able.  bisti/ted Water-  Oeerf/o  ~Bgure_L—  Ground. Glass  3  ;:  APPARATUS The e q u i p m e n t f o r t h i s work i n c l u d e d a pR" m e t e r , a c o l o r i m e t e r and an e l e c t r i c a l l y d r i v e n a g i t a t o r f o r s h a k i n g bottles.  A l l b u r e t t e s a n d p i p e t t e s u s e d f o r a n a l y t i c a l work  were c a l i b r a t e d . thods.  Gas a n a l y s e s were p e r f o r m e d by s t a n d a r d  L e a d s u l p h i d e was washed i n an e l u t r i a t o r  me-  ( F i g . 1)  which p e r m i t t e d easy removal of the substance. An apparatus  was d e v e l o p e d  f o r the continuous  deter-  m i n a t i o n o f pl-l o f a s o l u t i o n u n d e r a n y d e s i r e d a t m o s p h e r e ( F i g . 2} A new c o n t a i n e r ( F i g . 3) was d e v i s e d f o r t h e s h a k i n g experiments, ated.  b u t i t s p o s s i b i l i t i e s were n o t f u l l y  investig-  By s u i t a b l e m a n i p u l a t i o n , g a s c a n be w i t h d r a w n f r o m  t h i s apparatus  without d i l u t i o n of the contained  solution.  S o l i d s a r e e a s i l y i n t r o d u c e d , and s a m p l e s o f s o l u t i o n may r e a d i l y be removed by p i p e t t e .  EXPERIMENTAL METHODS OF XANTHATE DETERMINATION B e f o r e b e g i n n i n g t h e a b s t r a c t i o n work, an  attempt  was made t o f i n d t h e method b e s t s u i t e d f o r x a n t h a t e minations.  deter-  4 (i)  T i t r a t i o n with. I o d i n e ( S t a r c h I n d i c a t o r ) T i t r a t i o n of equivalent q u a n t i t i e s of EEtX s o l u t i o n at  d i f e r e n t pH v a l u e s y i e l d e d t h e f o l l o w i n g r e p r e s e n t a t i v e f i g u r e s  pH  Iodine T i t r e (cc)  ' 1.05  0.5  2.16  0.95  5.01  X 3  4.20  2.6  5.15  3.9  6.11  4.2  7.42  4.7  8.19  8.3  s  9.60  15.35  11.83  19.2  r e s u l t s i n d i c a t e that values obtained f o r iodine xanthate pH.  are u s e l e s s u n l e s s o b t a i n e d a t constant  S o l u t i o n s s h o u l d t h e r e f o r e be b u f f e r e d , i . e . , w i t h ITaHCOg,  b e f o r e d e t e r m i n a t i o n s a r e made. (ii)  O t h e r T i t r a t i o n Methods S i n c e K E t X i s a r e d u c i n g a g e n t and a l s o p r e c i p i t a t e s  many m e t a l s  f r o m s o l u t i o n , i t s d e t e r m i n a t i o n by t i t r a t i o n  v a r i o u s o x i d i z i n g a g e n t s a n d s a l t s was KMnO^:-The a d d i t i o n o f x a n t h a t e change f r o m p i n k t o y e l l o w .  with  attempted. gave an i n d e f i n i t e  I n the presence  of  color  diphenylamine,  e x c e s s K E t X p r o d u c e d a w h i t e p r e c i p i t a t e , w h i l e e x c e s s KMnO^  caused a^purple p r e c i p i t a t e  t o appear.  GuSO^-The. i n t e r a c t i o n o f G u S 0 precipitate  of C u ( E t X ) .  and K E t X gave a y e l l o w  4  E x c e s s c o p p e r was  2  use o f NH^OH as an e x t e r n a l i n d i c a t o r .  d e t e c t e d by t h e  T h i s method.-was f o u n d  t o be s a t i s f a c t o r y o n l y when c o n c e n t r a t e d s o l u t i o n s o f b o t h r e a g e n t s were u s e d . AgNQg:-Xanthate h e r e p r o d u c e d a w h i t e p r e c i p i t a t e Ag(E.tX) i g  E x c e s s s i l v e r was  • s o l u t i o n o f HC1.  d e t e c t e d by" an e x t e r n a l  T h i s method t o o was  of  indicator  f o u n d t o be good o n l y  f o r h i g h e r concentrations of the m e t e r i a l s i n question. K a B i O g t - T h i s formed a b l a c k p r e c i p i t a t e , and t h e p o i n t at  w h i c h p r e c i p i t a t i o n ' was .  c o m p l e t e was  difficult  to detect.  O e r i c Ammonium; S u l p h a t e : - T h i s r e a g e n t had t o be used i n  strongly acid  ( H S 0 ) s o l u t i o n t o prevent h y d r o l y s i s of the 2  4  c e r i u m s a l t , and t h e e f f e c t  o f t h i s a c i d on t h e x a n t h a t e  was  uncertain. KgGrjgO^r-An  external indicator  of K Fe(CB'} 4  6  was  used.  T i t r a t i o n s were n o t r e p r o d u c i b l e a t any c o n c e n t r a t i o n o f x a n t h a t e , and a p r e c i p i t a t e  o f unknown c o m p o s i t i o n was  Ni(M0 ) :- A p r e c i p i t a t e 2  the  formed.  of c o b a l t xanthate obscured  p o i n t at which the green color  d i s a p p e a r e d from the  sol-  ution. Co(H0g) ;-Similar to Hi(NO ) . 2  (iii)  g  £  G o l o r i m e t r i o Methods:E x p e r i m e n t s were p e r f o r m e d t o d e t e r m i n e x a n t h a t e b y t h e  amount o f t u r b i d i t y o r c o l o r p r o d u c e d by r e a c t i o n w i t h  certain  r e a g e n t s , and-by c o m p a r i s o n of, t h e s e r e s u l t s w i t h t h e v a l u e s  6 obtained  f o r mixtures  Of t h e m e t a l l i c o m i s e h e r e , and  of known  composition.  s a l t s , only 0uS0  4  and AgNOg showed p r -  only at very low concentrations.  At the  c e n t r a t i o n s e n c o u n t e r e d i n t h e a b s t r a c t i o n work, t h e ates which these and  substances  produced tended to  con-  precipit-  flocculate,  t h i s r u i n e d t h e measurement i n t h a t r a n g e . (NH/)0M0Q4:-Beilstein states:"Molybdate  gives i n min-  e r a l a c i d s o l u t i o n s with KEtX a red p r e c i p i t a t e , soluble i n organic solvents".  I t was  o f t h i s s u b s t a n c e was and  then  not  found however, t h a t the r e d s t a t i o n a r y , but  changed t o  colour  purple  t o b l u e by f u r t h e r r e d u c t i o n o f t h e m o l y b d a t e  with  xanthate.  XANTHATE ABSTRACTION AND (1)  Shaking In  E x p e r i m e n t s w i t h Pb3  t h i s work, m i x t u r e s  were, s h a k e n i n s t o p p e r e d termined  by t i t r a t i o n  RELATED WORK and  KEtX  o f s u l p h i d e and  b o t t l e s , and  with standard  xanthate  the l o s s o f x a n t h a t e  iodine preparation,  NaHCOg as a b u f f e r , u s i n g s t a r c h as an i n d i c a t o r . r a t i o n s were made on E5cc o f f i l t e r e d inal  xanthate  c o n c e n t r a t i o n was  b o t t l e s used i n a r u n .  PbS  solution  s o l u t i o n , and  and  All titthe  t h e same i n e a c h o f t h e  c o n c e n t r a t i o n was  de-  origfour  a l w a y s 25cc o f  f r e s h l y washed m a t e r i a l p e r l i t r e . The b o t t l e s were a l l made to up t h e same volume w i t h d i s t i l l e d w a t e r . A  7  RESULTS pH Run #1  Bottle  Before  PfcS + X  1  6.15  6.30  PbS^ X  2 .  6.21  6.37  1.0  PbS-f-X  3  6.13  6.28  1.0  KEtX  Ip T i t e r ( c c ) Before After  After  4 7.10 8.13 Average a b s t r a c t i o n  12 h r s .  2.85  2.7  63%  pH o f f r e s h l y washed PbS p u l p  5.8 3 .  Run #2  Bottle  PbS ~j- X  1  6.00  6.06 '  PbS+ X  2  6.13  6.21'  1.8  PbS + X  3  6.04  6.15  1.85  KEtX  pH Before After  I T i t e r (cc) Before After ?  —.—  4 6.91 7.43 3.05 • 38.3% Ave r a g;e a b s t r a c t i o n pH o f f r e s h l y washed PbS-—  Run #3  Bottle  pH Before After  1.7  I Titer(cc) Before A f t e r  •6.17  6.33  3.3  PbS-P X  2  6.14  6.29  3.2  PbS-f- X  3  6.13  6.30.  KEtX.  4  PbS -Fx PbS f X PbS +- X KEtX  1 2 3 4  6hrs.  5.90  1-  Bottle  Time o f Shaking  3.0  PbS-HX  Run #4  Time o f Shaking  —.—  7.10 8.22 10.1 Average a b s t r a c t i o n - — 6 6 . 7 % pH o f f r e s h l y washed PbS  18 h r s .  3.35 9.9 5.99  pH pH I Titer(cc) Before After Before After 6.20 6.39 2.8 6.12 6.31 ' 2.6 6.25 6.40 2.65 7.09 8.36 10.2 9.85 pH o f f r e s h l y washed P b S — 5.88 g  Time o f Shaking  Time o f Shaking 24 h r s Av. A b s t i s 73.3%  8 The t o be  pH  o f f r e s h l y p r e p a r e d x a n t h a t e s o l u t i o n was  a l w a y s n e a r 7.  This  figure increased  p e r i o d o f d a y s u n t i l a maximum of a b o u t 10  found  g r a d u a l l y over a was  reached,  pre-  sumably because of s l i g h t d e c o m p o s i t i o n of K E t X t o a l c o h o l  and  carbon d i s u l p h i d e . A s l i g h t vacuum was corked a f t e r shaking. ated  niticed  when the b o t t l e s were  A white t u r b i d i t y i n the l i q u i d  t h a t l e a d e t h y l x a n t h a t e had  un-  indic-  been f o r m e d .  GOMCLTTSICHS Xanthate i s abstracted increase w i t h the  f r o m s o l u t i o n i n amounts w h i c h  time of s h a k i n g .  Lead s u l p h i d e  n o t p r o d u c e enough l e a d i o n s t o r e a c t w i t h any  itself  does  appreciable  amount o f KIStX, so a n o t h e r more s o l u b l e s a l t o f l e a d must  be  p r e s e n t t o a c c o u n t f o r the p r e c i p i t a t i o n o f l e a d e t h y l x a n t h a t e . I f PbSO^ were p r e s e n t , ger  i t w o u l d p r o d u c e a r e l a t i v e l y much l a r -  lead ion concentration  t h a n PbS,  d i s a p p e a r a n c e o f the x a n t h a t e .  and  t h i s would e x p l a i n  the  A c a l c u l a t i o n reveals that  the  amount o f a i r i n a b o t t l e ( l O O c c ) w o u l d c o n t a i n s u f f i c i e n t  ox-  ygen t o o x i d i z e enough PbS  t o PbSQ^ t o a c c o u n t f o r any  xanthate  loss. The thate  amount o f P b ( l t X ) g p r e c i p i t a t e d , and  a b s t r a c t i o n , w o u l d be a f f e c t e d by  fluences  the s o l u b i l i t y o f t h a t s a l t  .  t h e pH,  hence t h e  xan-  s i n c e pH i n -  9 (ii)  As  in (i),  In Nitrogen  Atmoshpere  I n t h i s group o f e x p e r i m e n t s , n i t r o g e n was  bubbled i n t o  c e r t a i n b o t t l e s , so t h a t t h e e f f e c t o f a b s e n c e o f oxygen upon t h e a b s t r a c t i o n m i g h t be Run  #1  Bottle  PbS  X  1  PbS  X  2  • KEtX  3  KEtX  4  Run  #2  PbS  X  1  PbS  X  2  KEtX  3  KEtX  4  determined.  Atmosphere c o n t a i n e d  Iodine t i t e r a f t e r 18 h o u r s  air  3.25  nitrogen  5.6  air  '  10,1  nitrogen  10.2  air  2.65  nitrogen .  5.1  ' air.  9.8  nitrogen  •  10.0  REMARKS I n n i t r o g e n atmosphere, xanthate a b s t r a c t i o n i s a s e d , but m a t t e r how the  some o x i d a t i o n o f PbS thoroughly  the  apparently  sulphide  takes  i s washed and  place, how  decreno  quickly  subsequent n i t r o g e n treatment i s given. The  diminished  presence of n i t r o g e n i n the KEtX b o t t l e s e v i d e n t l y the r a t e ' o f d e c o m p o s i t i o n o f t h a t  substance.  10 (Hi)  Time o f W a s h i n g and Immediate X a n t h a t e A b s t r a c t i o n H e r e , t h e m i x t u r e s were o n l y s h a k e n m o m e n t a r i l y , t h e n  were f i l t e r e d Solution  and t i t r a t e d . Time a f t e r w a s h i n g o f PbS  KEtX  l  0  Titer cc 10.4  1  1 minute  5.9  2  2  "  5.85  3  5  "  5.7  4  10  "  5.6 .  CONCLUSIONS A l a r g e q u a n t i t y o f x a n t h a t e i s a b s t r a c t e d a l m o s t immediately.  Two f a c t o r s a r e i n d i c a t e d ; e i t h e r  (1) The method  o f w a s h i n g l e a v e s b e h i n d a c e r t a i n amount o f o x i d i z e d compounds, o r (2)  lead  The o x i d a t i o n o f PbS i s so r a p i d , t h a t i n  t h e t i m e w h i c h e l a p s e s b e f o r e d e t e r m i n a t i o n s c a n be made, a p p r e c i a b l e changes  takes place.  I t may be t h a t t h e r e i s f i r s t  a r a p i d o x i d a t i o n , f o l l o w e d b y one w h i c h p r o c e e d s a t a much slower (IV)  rate. Time o f W a s h i n g and Amount o f L e a d I o n A. L e a d i o n , as d e t e r m i n e d c o l o r i m e t r i c a l l y by t h e i n -  t e n s i t y o f r e d c o l o r p r o d u c e d w i t h d i - t h i o c a r b a z o n e , was f o u n d t o i n c r e a s e s l o w l y f r o m t h e t i m e o f w a s h i n g o f PbS.  With  this  a g e n t , h o w e v e r , q u a n t i t a t i v e r e s u l t s c o u l d n o t be o b t a i n e d , as it  was f a r t o o s e n s i t i v e . B.  A n o t h e r c o l o r i m e t e r i c method, w h i c h i n v o l v e d t h e  p r e c i p i t a t i o n o f l e a d i o n w i t h HgS w a t e r and t h e s t a b i l i z a t i o n  11 of  t h e . r e s u l t i n g c o l l o i d a l f o r m w i t h s u g a r and a c e t i c  was f o u n d t o y i e l d r e p r o d u c i b l e  1  acid ,  results.  Run_#l  Gone, o f Pb  1.  D i s t i l l e d water  2.  PbS m i x t u r e , 1 rain, a f t e r w a s h i n g  Ion-'-g/litre  ,0011  (  ,0065  3.  "  2 min.  "  "  .0067  4.  "  5 min.  "  "  .0067  5.  "  10 m i n ,  "  "  .0068  CONCLUSIONS There  i s an i n i t i a l h i g h c o n c e n t r a t i o n o f l e a d i o n ,  ( p e r h a p s c a u s e d by t h e p r e s e n c e o f oxygen i n t h e d i s t i l l e d water)  which would account f o r immediate  l a r g e p r o p o r t i o n o f added x a n t h a t e .  p r e c i p i t a t i o n of a  Lead i o n i n c r e a s e s  thenceforth slowly with time. (V)  R e l a t i v e P r e s s u r e Drops o v e r P b S , X a n t h a t e and PbS a n d  Xanthate. T h e s e p r e s s u r e d r o p s were d e t e r m i n e d w i t h a w a t e r manometer b o t t l e s w h i c h c o n t a i n e d a n i n i t i a l  e q u a l volume o f a i r .  F r e s h l y washed PbS gave a n o t i c e a b l e p r e s s u r e l o w e r i n g a l m o s t a t once*  PbS and X a n t h a t e showed d e c r e a s e s  initially;  a f t e r a l o n g time b u i l t  up p r e s s u r e s .  a slight  b u t soon b u i l t up a p r e s s u r e .  drop a t f i r s t ,  Xanthate alone y i e l d e d Re-  s u l t s were n o t e x a c t l y r e p r o d u c i b l e , s o no f i g u r e s a r e g i v e n .  CONCLUSIONS The p r e s s u r e d e c r e a s e i s c o m p l i c a t e d by s u c h t h i n g s as s o l u b i l i t y o f t h e a t m o s p h e r i c g a s e s , vapor p r e s s u r e o f t h e  12 s o l u t i o n s , and The  temperature  m a i n l o w e r i n g may  Pressure  surroundings.  he a s c r i b e d t o o x i d a t i o n o f  i n c r e a s e s i n x a n t h a t e m i x t u r e s t o the  of the v o l a t i l e (VI)  o f the  formation  carbon d i s u l p h i d e .  T i t r a t i o n of X a n t h a t e - v s - P r e s s u r e  Drop i n B o t t l e s  A sample r e s u l t h e r e w i l l i n d i c a t e t h e l a c k o f a t i o n w h i c h was Bottle  PbS.  correl-  observed. Drop  10cm  Iodine t i t e r cc  1  PbS  2  PbS  X  5.5  4.5  6  3  PbS  X  7.8  4.5  6  9.95  6  4-  EEtX  —1  5  EEtX  2.4  The PbS  H0  Time hrs.  6  of e r r o r i n such d e t e r m i n a t i o n s  i s the t e n d e n c y o f t h e s e two  h a v e an o p p o s i t e e f f e c t upon t h e (VII)  6  10.1  c h i e f source  and X a n t h a t e  — —  2  on  substances  to  pressure.  I o d i n e Titer-vs-G-as A n a l y s i s In  t h i s experiment,  t h e b o t t l e s were f i t t e d  s t o p p e r s b e a r i n g i n t a k e and a convenient  one,  shaking b o t t l e s  t o t h e gas  mixtures.  Sun #1  Bottle  1 2 3 4  The  rubber  s y s t e m was  h o w e v e r , s i n c e d r i v i n g t h e gas  contained  PbS EEtX PbS & X PbS & X  o u t l e t tubes.  with  not  f r o m the  b u r e t t e i n v o l v e d d i l u t i o n o f the  Amt. 0 d i s a p p e a r e d (from lOOcc approx) g  cc 2.0 0.1 1.2 1.4  i t i t e r after 18 h r s . ( c o r r e c t e d for d i l u t i o n ) g  10.05cc 3.5 3.1  13 Run  ,f2'  PbS  Bottle  •  Amt. Op d i s a p p e a r e d ( f r o m lOOec a p p r o x )  1  PbS  I titer after 15 h r s . ( o o r r e oted f o r d i l ' n g  1.8 c c  2  -  ~  2.5  " KEtX  3  0.0  9.8  PbS & X  4  . 1 . 6  3.0  C a l c u l a t i o n r e v e a l s t h a t n o t enough oxygen d i s a p p e a r e d to  account  f o r a l l t h e a b s t r a c t i o n , assuming the change:PbS  PbS0  4  Pb(EtX)  2  T h i s w o u l d a g a i n i n d i c a t e t h a t some o x i d a t i o n o f PbS t a k e s place before i t s t r a n s f e r t o the b o t t l e s . (Ylll) After Run  Iodine titer.,  G-as A n a l y s i s , and Lead  I o n B e f o r e and  Shaking  #1 Bottle  Ogdisa-pneared  ?b I o n Before A f t e r  1?_ T i t e r  PbS  1  2.2 c c  .0059  .0098  KEtX  2  0.2  .0009  .0006  9.8  PbS & X  3  1.9  .0011  .0017  2.9  In at  PbS and X a n t h a t e , t h e b u l k o f t h e l e a d i o n i s removed  once by x a n t h a t e .  I n t h e above e x p e r i m e n t ,  the xanthate  a b s t r a c t i o n and t h e l e a d i o n removed by K E t X a r e a p p r o x i m a t ely  chemically equivalent. OTHER MEASUBEMSNTS  (i)  Time was a v a i l a b l e f o r o n l y one d e t e r m i n a t i o n w i t h t h e  apparatus  shown i n F i g . 2, and t h i s was made on PbS i n an a t -  mosphere o f a i r .  (Other Measurements) Time M a r c h 10  11:40 12:30  «  torch  11  l i a r oh 12  M a r c h 13 IT  March  '  14  tt  M a r c h 15 tt  M a r c h 16  pH A.M.  2.62  "  2.63  5:30  P.M.  2.63  8:30  A.M.  2.65  9:15  A.M.  2.65  1:00  P.M.  2.70  5:15  P.M.  2.72  8:15  A.M.  2.80  5:00  P.M.  2.84  8:15  A.M.  2.88  5:30  P.M.  2.90  ' 8:15'A.M.  3.02  5:30 8:15  P.M. A.M.  3.10 5.27  tt  1:30  P.M.  3.33  tt  5:30  P.M.  3,34  M a r c h 17  12:00  A.M.  3.83  M a r c h 18  9:00  A.M.  4.61  M a r c h 19  3:00  P.M.  5.15  M a r c h 20  8:15  A.M.  5.24  tt  2:00  P.M.  5 29  tt  5:30  P.M.  5.31  8:15  A.M  5,36  5:30  P.M  5.40  M a r c h 21 tt  e  15 (Table.Cont'd) Day  . Time  pH  8:15 A.M.  5.42  5:30 P.M.  5.45  M a r c h 23  5:00 P.M. .  5.45  M a r c h 24  4:00 P.M.  5.56  M a r c h 25  10.00 A.M.  5.69  :  M a r c h 22  T h i s r i s e i n pH i s p r o b a b l y due t o r e m o v a l o f t h e a c i d forming  S= i o n by o x i d a t i o n , and t o s o l u t i o n o f b a s i c  con-  s t i t u e n t s from the g l a s s .  DISCUSSION The amount o f - e x p e r i m e n t a l  work done i n t h i s i n v e s t i g -  a t i o n does n o t w a r r a n t s t a t e m e n t o f d e f i n i t e  conclusions.  However, i t seems c e r t a i n t h a t t h e c o l l e c t o r i s removed f r o m s o l u t i o n by c h e m i c a l a c t i o n .  One may a l s o s a y t h a t t h e c o l -  l e c t o r does n o t c o a t t h e s u r f a c e causing  of mineral  p a r t i c l e , thus  i t s f l o t a t i o n , s i n c e t h a t w o u l d r e q u i r e f a r more  l e c t i n g agent than ever d i s a p p e a r s from s o l u t i o n .  col-  The a b s t r -  a c t i o n s a p p e a r s t o be due o n l y t o i m p u r i t i e s on t h e s u r f a c e , o r t o i m p u r i t i e s w h i c h go i n t o s o l u t i o n f r o m t h e s u r f a c e the p a r t i c l e ,  of  and i s a p p r o x i m a t e l y p r o p o r t i o n a l t o t h e amount  of t h a t f o r e i g n m a t e r i a l . The method o f d e t e r m i n a t i o n  s o m e t h i n g t o be d e s i r e d , w h i l e  of xanthate e v i d e n t l y be i t may/yseen t h a t t h e  i o n of a b s o l u t e l y pure l e a d s u l p h i d e  leaves  preparat-  i s not f e a s i b l e .  Since  t  t h i s work was done t h e whole p r o b l e m o f c o l l e c t o r a c t i o n upon  16 g a l e n a has been d e a l t w i t h i n a more r i g o r o u s 5 f a s h i o n by H. K. H e r d h i s xanthate  and  detailed  , who u s e s e l e c t r o m e t r i c t i t r a t i o n f o r  determinations.  17  BIBLIOGRAPHY 1.  R.  B.  Bennett,  Thesis,  '2.  R.  F. P e a r c e ,  3.  Handbook o f C h e m i s t r y  4.  Beilstein,  5.  H. H, H e r d ,  Thesis,  3,  1938. 1938.  and P h y s i o s ,  214,  1918.  Thesis,  1940.  p963,  1938.  

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