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The pyridine denitration of mannitol hexanitrate Brown, James Bay 1953

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THE PYRIDINE DENITRATION OF MANNITOL HEXANTTRATE by JAMES' RAY- BROWN  A Thesis submitted i n P a r t i a l Fulfilment of the Requirements f o r the Degree of Master of Science i n the Department of Chemistry  We accept t h i s thesis as conforming t o the standard required from candidates f o r the degree of Master of Science;.  Members of the Department of Chemistry.  The University of B r i t i s h Columbia April, 1953.  /  ABSTRACT The products of the reaction of excess anhydrous pyridine with D-mannitol hexanitrate at 30°C. have been analysed and five of the major components identified.  A gas consisting of nitric oxide, nitrous oxide  and nitrogen was evolved and D-mannitol-1,2,U,5,6-pentanitrate and pyridinium nitrate were recovered from the reaction mixture.  Twelve other  non-nitrogenous unidentified components were detected in the reaction mixture by paper-partition chromatography.  Establishment of a nitrogen  balance for the reaction indicated that complete removal of nitrogen from about 2 moles of pyridine and from about 0 . 2 5 moles of the hexanitrate occured during the formation of 0.75 moles of mannitol pentanitrate.  ACKNOWLEDGEMENTS  The writer wishes to express his sincere thanks to Dr. L. D. Hayward for his encouragement and willing assistance i n the direction of this investigation. Grateful acknowledgement i s made also to the National Research Council of Canada for a summer granto  TABLE OF CONTENTS Page Introduction  ...  ...  ...  ...  ...  1  Historical Introduction Discussion of Results Conclusions  ...  ...  1 ...  ...  ...  ...  Experimental  . 1 ; ...  ...  ...  ...  13  ...  ...  23  -  Special PrecautionsMaterials and Methods  ...  ......  Preliminary Experiments  23  .:  ... • 2U  ...  Determination of the Rate of Gas Evolution Analysis of the Evolved Gas  ......  25  ... ...  ...  Fractionation of the Water Soluble Reaction Products Isolation of Pyridinium Nitrate  .......  25 ' 28 '  ' ...  29  ...  -29  Adsorption Chromatography of the Acetone-Soluble Residue  Determination of Pyridine and Pyridinium Nitrate in the Residue (a) Precipitation as the Copper Thiocyanate Complex (i) Estimation of Pyridine ( i i ) Estimation of Pyridine in Pyridinium Nitrate  ...  30  ...  31  (b) Precipitation as Pyridinium Perchlorate  31  (c) Separation by Dialysis (i) Dialysis of Pyridinium Nitrate ( i i ) Dialysis of theResidue  32  ...  32  (d) Separation by Ion Exchange (i) Preliminary Tests ( i i ) Treatment of the Residue with Amberlite I-R-U5  33 •••  33  continuing Table of Contents  Page Experimental Determination of Pyridine and Pyridinium N i t r a t e .in the Residue (e) T i t r i m e t r i c Determination  ..  ( i ) Prel ( i i ) Volumetric Analysis of the Water Soluble Reaction. . Products . . . Bibliography  ...  ...  . . . . . . .  ...  . . . .  ...  ...  35 36  - 1  -  INTRODUCTION Since the f i r s t discovery of the pyridine denitration of mannitol and dulcitol hexai itrates to the corresponding pentanitrates no attempts have been made to determine the mechanism of the reaction.  However, since  the reaction has recently been shown to result in specific denitration of both mannitol- and dulcitol-hexanitrate in the three (or chemically equivalent U-) position, i t has become important as a possible method of a making available/specific secondary hydroxyl group in poly.hydric alcohols and possibly also in sugar molecules.  This specificity coupled with the  desirable characteristics of nitrate groups as carbohydrate "blocking groups" suggedis the use of the carbohydrate nitrates as intermediates in sugar syntheses.  Further development toward this goal required, the  investigation of the mechanism of the pyridine-carbohydrate nitrate reaction. The present work describes the isolation and identification of the major by-products of the reaction of pyridine. with vmannitollihexanitrate, together with preliminary studies on the rate of the reaction. HISTORICAL INTRODUCTION The pyridine denitration of mannitol hexanitrate was f i r s t discovered by Wigner in 1°03 (2#) when he found that pyridine was av.jmore selective denitrating agent than Tichanowitsch s ammoniacal ether (2$.). 1  The latter reagent was stated by Wigner to cause some deep-seated decomposition as a result of i t s action as a caustic a l k a l i . did not show this unddsirable secondary effect.  Pyridine, however,  The method described  was  to dissolve the mannitol hexanitrate i n six times i t s weight of pyridine with cooling, when necessary, to prevent the reaction from becoming too vigorous.  The reaction was accompanied by the evolution of large amounts  of "nitrous vapor" and by a gradual change in the solution from colorless to bright yellow.  The crystalline pentai itrate was isolated by  precipitating with water and was purified by crystallization from aqieous ethanol. No further investigation of the reaction was attempted until Hayward, in 1951, showed by methylation, denitration and periodatej oxidation that the partialdenitrating a. ction of the pyridine i s specific to the 3 - (or equivalent It-) position of the mannitol hexanitrate molecule (6). McKeown, in 1952, showed that the 3 - (or k-) position i s also the point of attack of pyridine on dulcitol hexanitrate (10). The action of pyridine and other weak bases on nitrated carbohydrate derivatives has been investigated by several workers. Walter (25) in 1911, noted that guncotton, soaked with one of dimethylaniline, phenylhydraz ine, o- or p-toluidine or naphthylan ine, and l e f t in the dark, suffered a. gradual change i n color indicating decomposition. Angeli (1) found that pyridine-moistened  nitrocellulose gives  an 60$ yield of the original weight of nitrocellulose with a nitrogen content reduced from an original 12% to 9-10% indicating decided decomposition. Giannini (5) extended this work in 192k> He found that a gas containing carbondioxide, n i t r i c oxide, nitrous oxide and nitrogen, ,was given off and that the carbohydrate product, after U5 days i n contact with  pyridine, had approximately the molecular weight of a biose unit.  In  19kh Gladding and Purves (6) found that pure, dry pyridine caused a vigorous.decomposition of dissolved, stabilized guncotton at 100°C. Nitrogen dioxide was evolved as a volatile pyridine complex which readily crystallized above the solution on cooling. Ryan and Casey (15) studied the effect of primary, secondary and tertiary amines on various carbohydrate nitrate esters.  Dimethyl  aniline reacted with mannitol hexanitrate at an elevated temperature to evolve a gas consisting of 70% Nitrous oxide and 30% nitrogen. Much work has recently been done on the action of hydroxylamine, methoxyamine and their corresponding hydrochlorides on pyridine solutions, of carbohydrate nitrates. The reactions observed were assumed to be caused by the ammonia derivative with the pyridine acting merely as solvent. In 1946 Segall (18) found that excess hydroxylamine i n pyridine at room temperature, acted on cellulose trinitrate to give a cellulose dinitrate with the evolution of one mole of nitrogen per mole of anhydroglucose. nature. pyridine. evolved.  The nitrate groups attacked proved to be secondary i n  Unlike other cellulose nitrates, theproduct was stable to Methoxyamine acted similarly except that no nitrogen was With excess hydroxylamine hydrochloride the product appeared to  be a cellulose ketoxime dinitrate and the gas evolved consisted of 8$% nitrous oxide and 1$% nitrogen. Hayward (7) followed up this work by investigating the action of hydroxylamine i n pyridine on methyl- *,-and/3 trates.  -D-glucopyranoside tetrani-  In preliminary experiments he found that an alcoholic solution  '  -  k-  of hydroxylamine had l i t t l e or no effect on methyl- «< -or /3-D-glucoside tetranitrate.  When the compound was dissolved in anhydrous pyridine,  highly colored products were rapidly formed but no gas was evolved. The  -isomer was recovered in 16% yield after four and one half hours,  and in 60% yield after sixteen hours.  A vigorous exothermic reaction  ensued on addition of hydroxylamine in anhydrous pyridine to methyl- /3 D-glucoside tetranitrate.  Nitrogen gas was evolved in the ratio of 1.3  moles per mole of tetranitrate, and the product contained methyl- ^ -Dglucoside-2,3,6-trinitrate (53%), methyl- /& -D-glucoside-3,6-dinitrate (33%) and unidentified methyl-  -D-glucoside trinitrate.  The action of hydroxylamine hydrochloride in pyridine on methyl.£ -D-glucopyranoside tetranitrate, investigated by Rooney ( 1 5 ) , was slower and more complex. The gas evolved was 87$ nitrous oxide and 30% nitrogen, and the carbohydrate products appeared to be a mixture of partially denitrated methyl glucoside and completely denitrated polyoxime products. Methyl-/^-D-gluco-pyraao8S:de-2,3y6-trinitrate and a substance believed to be methyl-y^ -D-glucopyranoside-2,6-dinitrate  were isolated.  An investigation of the action of guinoline on methyl-/3 -Dglucoside tetrai itrate by Swai (20) showed that a'partial denitration occurs with the evolution of a gas. DISCUSSION OF RESULTS The reaction of mannitol hexanitrate with pyridine (denitration reaction), carried out in air, led to the evolution of a brown gas and the formation of a thin film of nearly colourless crystals on the walls of the glass vessel above the solution.  This crystalline material (m.p. 116 -  117°C. after crystallization from methanol) was tentatively identified as  - 5 pyridinium nitrate by means of a mixed melting point with an "authentic sample of pyridinium nitrate.  When, however, the reaction was carried out  in the absence of a i r i n the Toricellian vacuum of a Lunge Nitrometer, the gas evolved was colourless and no crystalline material was deposited.  The  gas turned red-brown on admission of commercial oxygen, but did not deposit any solid material.  Consideration of the reaction indicated that the  following components could be anticipated in the gaseous product: nitric oxide, nitrous oxide, carbon dioxide, carbon monoxide, nitrogen and pyridine vapour.  Since the gas was colourlessbut reacted with oxygen  to give a red-brown gas, n i t r i c oxide must have been present and nitrogen dioxide and oxygen absent.  The alkaline, oxidizing conditions prevailing  in the reaction mixture made the formation of gaseous ammonia, hydrogen cyanide, formic acid, formaldehyde and hydrocarbons unlikely. Water-\apour was shown to be absent when no solid was deposited on admission of oxygen to the gas. A method i>or the analysis of such a mixture was not available in the literature.  However, several reagents, described as absorbents for  n i t r i c oxide were chekked, in the Orsat apparatus, for absorption of commercial nitrous oxide.  These were 1$% aqueous sodium sulphite, 1% in  potassium hydroxide (a), 20% potassium hydroxide (11), 0.1 normal sulphuric acid 1% in potassium permanganate (23) and 0.1 normal potassium hydroxide 1% in potassium permanganate (9). In each case the nitrous oxide was slowly absorbed.  Aqueous ferrous sulphate, recommended by Scott (1^) was  not tested because the unstable complex formed with nitricoxide i s reported to have an appreciable vapour pressure of n i t r i c oxide in equilibrium with i t (2.4).  - 6 -  The nitrogen dioxide formed by reaction of oxygen with the gas was found to react f a i r l y readily with mercury i f sufficient surface was available for reaction,  The disappearance of the characteristic colour  of the gas was taken as evidence for the completion of the reaction:  2 N 0 + 2 0 + Hg  Hg (NOj^.  2  Carbon monoxide, i f present, would, of course, be oxidized to carbon dioxide during this reaction.  -he possible components then remaining  would be nitrous oxide, carbon dioxide, nitrogen, pyridine vapour and the excess oxygen. The nitrous oxide was absorbed i n $$% ethanol (18) would also absorb the pyridine vapour.  which  The carbon dioxide was absorbed  in 1+0$ potassium hydroxide and the excess oxygen i n alkaline pyrogallol (2*t). The percentage of pyridine i n the gas could be calculated (from the ratio  '  of i t s vapor pressure at the temperature of the reaction to the atmospheric and  pressure) subtracted from the percentage of the gas absorbed i n ethanol to A  give the true percentage nitrous oxide. However, since i t s concentration was small and f a i r l y constant ( 2 . 5 -  2.8$),  the correction was not  considered necessary and the total gas absorbed i n ethanol was calculated as nitrous oxide.  The absorption of oxygen by ethanol was found to be  n i l within the experimental error.  (The volume of the gas increased due  to the pressure of ethanol vapour but returned to the original when the latter was absorbed in hP% potassium hydroxide)• In a test with commercial nitrous oxide ethanol was found to absorb 9Q»S% and 9%*$%, the absorption tadng about l j hours.  In the  analysis of the oxygen-treated gas, a repass through the ethanol pipette was required after absorption in potassium hydroxide to establish how much of the gas absorbed was ethanol. Within the limits of the experimental  f  -  7  -  error (about 1*5%) the loss i n volume of the gas on passage through potassium hydroxide was due to absorption of ethanol vapour* The molecular weight of the gas unabsorbed during the analysis, determined by the vapour density method (3), was found to vary between 28.5 and 29»5>.  The variable discrepancy between these values and the theoretical  value for nitrogen was attributed to contamination of the unabsorbed gas with pyridine.  The composition of the gas was found to vary considerably  from run to run in spite of extreme care i n attempting to control the reaction conditions.  T  he rate of evolution of the gas during each reaction  was also found to vary.  It appeared that the observed variations might be  the result of a varying water content of the hydroscopic pyridine. However, use of pyridine dried over barium oxide and freshly fractionally d i s t i l l e d through a 20 inch Widmer column(boiling range 115.0  - ll5.5^corr.)  did not lead to reproduceable gas compositions or rate curves.  In Fig. 1.  are plotted moles of gas per mole of mannitol hexanitrate for several runs using anhydrous pyridine. To check the possibility that the absolute number of moles of nitrogen evolved in the various forms was a constant quantity, the itate and analytical data were calculated to gram atoms of nitrogen per mole of mannitol hexanitrate. The resulting plots, while not reproduceable (as i s shown inJFig. 2) were more closely grouped than the plots of moles of total gas evolved (Fig. l ) . The effect of water on the reaction was further tested. Denitrations were carried out with the addition of O.OOlu mole of water in one case and 0.0028 mole i n another. amount of nitrogen evolved resulted.  A marked decrease in the total  In the f i r s t case the yield of gas  r«4  O  i>o  <oo  HO  (0>J  (io  (4-o  two  i a  0  zoo  z -" 2  - 10  -  calculated as nitrogen was reduced by about one quarter and in the second by about one half of the average yield from an anhydrous reaction. plots'F and G  The results are plotted i n Fig.2.*,  The composition of the gas  was not significantly altered, as can be seen by reference to Table I, but the yield of crude mannitol pentranitrate was apparently increased. However, since the nitrogen evolved during these reactions was significantly less than that evolved during an "anhydrous" reaction and the colour of the reaction mixture diluted to 250 ml. was much lighter, i t i s indicated that the reaction did not proceed as far in these cases as i t did under under anhydrous conditions.  Therefore, i t i s l i k e l y that the isolated  products contained unreacted mannitol hexanitrate. The water soluble reaction products, (residue) after reduction to dryness, wereextracted with acetone (about 0 . 5 $ by weight did not dissolve) and subjected to fractional crystallization from that solvent. While a small sample of pyridinium nitrate was isolated by this method, no further separation was possible. T  n e  pyridinium nitrate was eliminated  from the residue by neutralization with potassium hydroxide but i t was found that the coloured components in the resulting residue were no more easily separable from potassium nitrate by fractional crystallization than they had been from pyridinium nitrate.  A change i n the colour of the aqueous  solution of the residue from yellow-orange to brick-red during the neutralization, indicated that a reaction in addition to neutralization had taken place. Pure pyridinium nitrate was isolable from the residue by removal of the coloured components with activated charcoal. Paper-partition chromatorgraphy of the residue separated i t into  -  11'-  TABLE I RESULTS OF THE ANALYSES OF THE GASEOUS PRODUCT  Run  A  Time of Reaction hrs. min.  Vol. of water added  Gm. Atoms weight N evolved M.P.N.-* in 4 hrs.  67.3  ' 14.8 .14.7  17.9 18.2  2.98 (3 hr) 1.398 g  2  nil  3  Composition of Evolved Gas % N9 % NO $N 67.5  2  2  B  3  20  nil  66.3  15.2  18.5  3.12 (3hBr. 1.61 g. 20 min.)  C  U  30  nil  65.7  15.3  20.0  3.04  1.48 g.  D  5 '  nil  68.7  9.8  21.5  3.04  1.61 g.  E  4  nil  63i 8  18.2  18.1  2.92  1.64 g.  F  4  0.025 ml.  63.5  16.4  20.3  2.16 ,  1.75 g.  G  4  0.05  ml. 60.8  16.5  22.8  1.49  1.72  •& Mannitol Pentanitrate.  - 12  -  fourteen components with Rf values ranging from 0 . 0 to O.J.  The developing  solvent had the composition butanol k0%, water k9%, ethanol 10$ and ammonia 1% by volume.  The spots were detected by their ultraviolet fluorescence  and by development with a 1% solution of aniline trichloroacetate in glacial acetic acid.  Interpretation of the spots was made d i f f i c u l t by their number,  by considerable trailing of some of the compcraerits and by the relatively high proportion of pyridinium nitrate in the residue. A very large spot with aa Rf value of 0 . 3 5 was identified, by comparison with a standard, as pyridinium nitrate. 'Mannitol pentanitrate gave a spot with Rf value 0 . 9 as identified by comparison with a standard. This spot did not fluoresce appreciably but was detercted as a salmon pink spot on treatment with aniline trichloroacetate.  The Rf. values of the  spots and their color are given in Table II. The components of the neutralized residue did not separate very well on partition chromatographing,  but seven spots appeared under ultra-  violet i±radiation and one on developing with aniline trichloroacetate. One of these spots was probably produced by potassium nitrate and another by mannitol pentranitrate.  '^hree of the spots appear to be due to compounds  also present in the untreated residue and therest to compounds produced by the action of the potassium hydroxide.  Adsorption chromatography of the  acetone soluble portion of the residue on s i l i c a gel using acetone as the eluting solvent, M to six fractions which were detected by their reaction or non-reaction with diphenylamine reagent.  Most of the residue was collacted  in the f i r s t and fourth fractions, the f i r s t containing a small quantity of brown gum and the fourth, heavy yellow needles contaminated with an orange syrup.  However, i t appeared that the method would be useful for  - 13 -  TABLE II PAPER-PARTITION CHROMATOGRAPHIC ANALYSIS  0. .016  .07 .09  .10 .15 .18 .19 .19 .20  .22 .2U .25" .26 .28  .29  .32 .35 - .35 .Uo  .hk '  •50 .63 .9  yellow-orange yellow orange orange sky blue yellow (ATCA) orange blue orange oran ge orange sky blue l i g h t orange l i g h t orange yellow blue yellow quench blue blue yellow l i g h t orange sky blue salmon pink  X  X  X  X  CD  CD H  O  £> -P nj CD CD O  al o H •rl -rl O Q -P W  >  X  X  X  o  CD «N =H  X  X  X  IA  cfl _=f  B« a iH o  •rl >» •P rO o  (fl U  TS  CD -P  X  X  X  X  Fraction -retained  cfl  —i  by I-R-U5  *  Dialyseable fraction acetone in sol.  o B10j^ soluble fraction  C10j^ precipitate J fraction  Color Total Residue  Rf Value  Total Neutralized Residue  OF RESIDUE FRACTIONS  xTr xTr'  X X  X X  xTr  X  X  X  X X X X X  X X  X  X X X  X  X X  •  X  X  X  X  xlr X  X  X  X  xTr X  X X X '  X  X  X  X  Tr = trace. The colors appeared under u l t r a - v i o l e t i r r a d i a t i o n except where a n i l i n e trichloroacetate (ATCA) i s specified, i n which case development of the chromatogram with that reagent was required.  "  -Irresolution of the residue only after the pyridinium nitrate had f i r s t been removed. A quantitative method for determination of pyridine was sought in order that both the amount of pyridine used in the reaction and the amount in the form of pyridinium nitrate could be determined. T  he method of Spacu ( 1 9 ) ,  designed for the estimation of copper,  was found to give low yields (96%) of the green pyridine complex with copper thiocyanate (Cu(C^H^N) (CMS)2) when 1 mole potassium thiocyanate 2  and 0.5 molar cupric sulphate were added in slight excess to a standard 0.1 molar pyridine solution.  Addition of further precipitating reagents  to the solution lead to precipitation of white potassium thiocyanate. The method was therefore considered unsatisfactory. Precipitation of the pyridine from a glacial acetic acid solution of the residue as pyridinium perchlorate would have the advantage that an excess of precipitant could be removed from thefiltrate by precipitation with potassium acetate. free from salts.  Thus the remaining residue would be relatively  The method was therefore applied to the residue in  spite of the fact that i t gave only 9$% of the theoretical yield with a standard pyridinium nitrate solution.  The resulting precipitate was a  bright yellow instead of white as expected.  The indication was that  coloured cations were present in the solution of the residue that precipitated with perchlorate anions.  On solution of the precipitate in acetic  acid, removal of perchlorate with potassium acetate and cautious reduction to dryness, a part white, part brown powder was obtained (weight about 0.3 gm.).  The white material was assumed to be potassium acetate. The perchlorate ions were similarly removed from the yellow  - 15 -  f i l t r a t e and the solution evaporated.  Acetone extraction removed the  coloured components from the resulting light brown solid (assumed to be mostly potassium acetate) and evaporation of the remaining solution ikft 0 . 1 gm. of dark orange-brown, amorphous, hygroscopic materialo The spots produced by paper-partition chromatography of the perchlorate-precipitated fraction and the soluble fraction, corresponded to those produced by chromatography of the potassium hydroxide neutralized residue. he fraction precipitated -frith perchlorate ions gave five spots, T  one of which appeared to be potassium acetate. The unpreqpitated fraction of the residue showed two spots, one being mannitol pentanitrate, and a faint spot for potassium acetate. Sines the denitration reaction could involve polymerization of the pyridine, i t was thought that dialysis of the residue might lead to some separation.  Preliminary tests showed that pyridinium nitrate easily  passed through cellophane dialysis tubing. Almost the entire residue passed through the pores of the membrane during dialysis,- leaving only 0 . 0 2 gm. of solid material from an original 0.8 gm. of residue. he solid material in the dialysing. solution could be T  extracted with acetone which dissolved out the pyridinium nitrate, mannitol pentanitrate and three other components as-shown by papergrams of the two resulting fractions.  '  -  T'h Rf values of some of the spots (10 appeared under ultraviolet) e  produced by the acetone insoluble fraction did not correspond to those .of the residue, but i t appeared that these values were dependent on the amount of pyridinium nitrate present.  The method of dialysing might, however,  have produced some changes in the residue.  The fact that acetone dissolved only part of the dialysed material but practically a l l of the original residue supported the latter view.' The solid remaining in the dialysis bag remained at the point of application when subjected to paper-partition chromatography. PyridiniQm nitrate was found to be nearly completely removed from a standard aqueous solution by the weakly basic anion exchange resin Amberlite I-R-U5*  Cn application of the method to the residue, however,  i t was found that the resin retained a part of the residue which could be recovered from the regenerating bicarbonate solution by reduction to dryness and extraction with acetone. (0.32 gm.)  The material recovered in this way  appeared to be mostly colorless crystals of sodium bicarbonate  on which was deposited a small quantity of very dark brown material. The treated residue solution yielded 0.11 gm. of hard, amorphous, f a i r l y dark orange-brown material which gave nine spots on a paper-partition chromatogram, one of which corresponded to mannitol pfentanitrate. spot appeared for pyridinium nitrate.  No  The material retained by the  resin gave one spot corresponding to one of those from the neutralized residue and two indistinct spots for components readily detectable in the fraction unaffected by I-R-U5*  The results of the chromatography  experiments are summarized in Table II. An estimate of the amounts of pyridine remaining after reaction and pyridinium nitrate produced was obtained by titration of the reaction . mixture after removal of the mannitol pentranitrate and dilution with water to 2^0 ml. ' End points were detected with a calibrated Beckman model "G" pH meter equipped with standard glass and saturated calomel electrodes. A 25 ml. aligfuot of the solution was f i r s t titrated with 0.2 - 0 . 3 N.  potassium hydroxide for nitrate ion and then with 0 . 6 normal sulphuric acid for pyridine.  The pyridine titrated thus included that originally  bound as pyridinium nitrate.  The accuracy, as determined by analysis of  standard samples, was £ 0 . 3 $ for both titrations.  The loss of the volatile  pyridine involved in the manipulation of the reaction mixture was found to be $.&$  - 0 . 2 $ by subjecting a pyridine sample to the transferring and  filtering required of the reaction mixture.  After determination  of the  volume of potassium hydroxide solution required, another 25 ml. alLigupt of the solution was treated with a known excess of potassium hydroxide and reduced to dryness for determination of the weight of pyridinium nitrate-free residue. With these data i t was possible to make a rough calculation of the composition and weight of the reaction products to be expected in the residue and to compare the calculated weight of residue to that found. The calculations showed that there was essentially no nitrogen to be expected in the residue other than that determined as nitrate ion, that carbon and hydrogen were present in the approximate ratio of 1:1 oxygen was present in very small quantity.  and that  This composition i s inconsis-  tant with the character of the residue since i t indicates the presence of only hydrocarbon material.  However, i n calculating the number of moles  of oxygen in the residue, i t was assumed that a l l of the oxygen as nitrate ion came from the reactants, while the probability i s that i t came in large part, from the water into which the reaction products were poured. When i t was assumed that the acidic material titrated was produced from nitric oxide after the reaction, the ratio of carbon to oxygen became approximately 3:1 and the water solubility of the residue was then consistant with uie  -18calculations.  Approximately two moles of pyridine were used i n t h e  reaction f o r each mole of mannitol hexanitrate added.  The discrepancy  between the calculated and experimental values f o r the weight of residue must be attributed to the presence i n the reaction mixture of a v o l a t i l e , pyridine and water soluble f r a c t i o n which would be l o s t i n the evaporation of the neutralized residue to dryness.  The r e s u l t s of the volumetric  analyses for three denitration runs are given i n Table I I I .  Table IV.  gives the composition of the residues calculated from the a n a l y t i c a l data. The value f o r pyridine added was corrected f o r losses i n manipulation. The experimentally determined weight of residue given i n Table IV. was that obtained from the weight of the neutralized water soluble reaction products by subtracting the known weights of potassium n i t r a t e and potassium hydroxide.  The calculated weight of residue i s the weight of  pyridinium n i t r a t e - f r e e residue.  •  «  CONCLUSIONS The p r i n c i p a l reaction which occurred on solution of mannitol hexanitrate i n pyridine resulted i n the replacement n i t r a t e ester group of the hexanitrate by hydroxyl. or racemization occurred, the replacement of a proton f o r a nitronium i o n .  of the number three Since no inversion  probably involved substitution  The source of this proton remains un-  known since the r e s u l t s of the present i n v e s t i g a t i o n indicated decomposition  profound  of both the pyridine used i n the reaction and the mannitol  hexanitrate not recovered as the pentanitrate.  Paper-partition  chromatography indicated that no l e s s than fourteen s o l i d products were formed during the reaction and analysis of the gaseous product showed that i t contained three components.  The substitution of the nitronium  *  19  -  TABLE III VOLUMETRIC ANALYSIS OF THE WATER-SOLUBLE REACTION PRODUCTS  t  Run  E  F  G  moles  moles  0.0011+  0.0028  * 0.00553.  0.00553  0.00553  Mannitol pentranitrate recovered  o.ooi+03  0.001+30  0.001+23  Mannitol hexanitrate lost in reaction  0.00150  0.00123  0.00130  Pyridine added  0.222  0.222  0.222  Pyridine recovered  0.211  0.210  0.212  Pyridine used in reaction  0.011  0.012  0.010  Gm. Atoms of nitrogen in gaseous prod.  0.01613  0.01221  0.00798  Nitrate ion recovered  0.00902  0.00919  0.00958  moles Water added Mannitol hexanitrate added  0.0  - 20 -  TABLE IV . MATERIAL BALANCE BASED ON THE ANALYSIS OF THE AQUEOUS AND GASEOUS REACTION PRODUCTS  r  Run  (  E  F  G  moles  moJbes  moles  -0.001  0.002  :0.00ii  Carbon i n the residue  0.06U  0.065  -0.055  Hydrogen in the residue  0.063  0.063  0.053  Oxygen i n the residue  0.019  0.016  0.019  Calculated weight of residue  1.13 gm.  1.13  Determined weight of residue  0.097  0.01+6 gm.  Nitrogen i n the residue  gm.  gm.  1.07 0.102  gm.  gm.  - 2-1 "  ion into the pyridine ring with ejection of a proton appeared unlikely in view of the extreme conditions required for the nitration of pyridine (12). Nitrogen was recovered in simple molecules far in excess of one gram atom per mole of mannitol pentanitrate produced (six gram atoms of nitrogen per mole of mannitol pentanitrate were produced in the case of the anhydrous reaction).  In fact, the calculations based on the analyses  of the reaction products from the anhydrous denitration account for a l l the nitrogen content of the reactants i n mannitol pentanitrate unreacted pyridine, n i t r i c oxide, nitrous oxide, nitrogen and nitrate ion. In the two denitrations done with the addition of water to the reactants, the calculations showed that a small amount of nitrogen was present in the unidentified products.  However, an increased yield of  water-insoluble product was obtained from these two reactions (Table III) and this increase could be accounted for by assuming the presence of unreacted hexanitrate.  Thus a nitrogen balance was achieved in the three  cases which indicated the unidentified products to be nitrogen-free. The hexanitrate not recovered as pentanitrate must then have been completel y denitrated, probably with further oxidative degradation.  The pyridine  used in the reaction must also have been degraded at least to the extent of ring opening to eliminate the nitrogen. It may be conjectured that these products were low molecular weight unsaturated alcohols, aldehydes and acids. is glutaconaldehyde (27).  One possible component  It has an empirical fommula (C^H^Og) consistent  with the calculated composition of the residue (C3H3O) and has two forms depending on the pH: structure;  in acid solution i t has the yellow-brown dialdehyde  in basic media i t i s in the form of the dark r ed enolate ion.  - 22 -  OHC-CH-CH = CH-CHO 2  O-CH = CH-CH = CH=CHQ + H  acid  +  base  The presence of this compound or similar ones i n the reaction product would account for the observed colour change on neutralization of the residue and for the extraction of a portion of the residue by an anion exchange resin. The major problem in the resolution of the solid residue was the removal of the very large quantity of pyridinium nitrate.  Very mild  conditions were required because the expected components would be subject to ready polymerization and decomposition.  Alkaline solutions had to be  avoided because of the possibility of aldol type condensations and Cannizano disproportionations.  Of the methods" utilized in this work, treatment of  the residue in aqueous solution with the weakly basic anion exchange resin amberlite i-R-kB appeared to be the one most-suited for the removal of the pyridinium nitrate.  -In addition, i t separated at least one coloured  anionic component from the rest of the residue.  The treated residue could  then be subjected to adsorption chromatography on unactivated s i l i c a gel using acetone followed by methanol as the eluting solvent. 'The fluorescence of the fractions under ultraviolet irradiation should serve to differentiate them.  The number of components i n each fraction could be determined by  application of paper-partition chromatography.  Further work should be done  on the total analyses of the reaction products.  • This should include  analysis of the crude mannitol pentanitrate and of the neutralized residue for nitrogen.  An investigation to ascertain the identity of the compon-  ents evaporated during the reduction of the neutralized residue to dryness should also be undertaken.  - 23 EXPERIMENTAL Special Precautions The explosive character of mannitol hexa- and pentanitrates made i t essential that special precautions be taken in handling these compounds and the solid byproducts of the denitration reaction.  The mannitol was  nitrated in 5 gram lots and no more than the product of one nitration was storedin the dry state at one time.  Distillations were carried out on  a steam bath at reduced pressure to a minimum volume of residue of approximately 25 ml.  Further drying was accomplished at room temperature in a  vacuum desiccator. Materials and Methods Nitric Acid.  Red fuming nitric acid supplied by Baker and Adamsonvas  used for a l l nitrations* Pyridine.  A.R. pyridine supplied by The British Drug Houses was used  for the denitrations. Mannitol.  D-Mannitol supplied by theSchering-Kahlbaum Company, Berlin, 20  - 0.53* (C, 7.00) HgO was  Germany, melting point 166-167°C,  used in the preparation of mannitol hexanitrate. D-Mannitol-1,2,3,U,5,6-hexanitrate  .  .  was prepared in five gram lots as  described by Pattd'son and Todd ( 1 4 ) . Diphenylamine Reagent used in testing for .nitrate was prepared by the method of Mulliken (13). Ion Exchange Resin.  Amberlite I-R-U5 anion exchange resin supplied  by Rohm and Haas Company, The Resinous Products Division, was used for the removal of anions.  - 2k Cellophane 1^/g inch Osmosis Membrane supplied by  Dialysis Tubing.  Central Scientific Company, was used i n six inch lengths, tied off at the bottom with a rubber band, for a l l dialysis experiments. Paper-Partition Chromatographic Paper.  Watman No.l. Paper, supplied  by ¥. and R. Baker, Ltd. was used.for"the paper-grams. Silica Gel.  Technical Dessigel was ground in a corn mill and sieved.  The 80-115 mesh portion was used. Paper-Partition Chromatography. . Spots of the material to be analyzed were applied to t*he 50 cm. paper strip 8 cm. from the top and at intervals of 3 cm.  The concentration of the material on each spot was  built up by repeated/application of thesolution of the material from a capillary-tipped pipette, the spots allowed to dry between each application.  The chroroatogram was'developed by suspending i t from  a trough of the developing solvent (k0% butanol, k9% water, 10$ ethanol and 1% ammonia by volume) in an insulated chromatography tank with a Light-fitting .cover.  After allowing' the developing process to proceed  for twenty-four- hours, the chromatogram was removed from the tank and allowed to dry.  It was then investigated i n a photographic dark-room  • under ultra-violet irradiation. • Spraying of the chromatogram with 1% aniline trichloroacetate in.glacial acetic acid by means of an atomizer then followed.  The chromatbgram was allowed to dry and then  heated i n an oven for three minutes. - Spots produced by the aniline - trichloroacetate appeared the following day. ®  Preliminary Experiments Mannitol hexanitrate (5 grams) was dissolved in 30 ml. of pyridine i n a 250 ml. erlenmayer flask ( 7 ) . The solution changed from  - 25 colourless to yellow-orange i n twenty minutes.  A frosting of crystals on  the walls of the flask ab ore the solution had also appeared by this time. In one half hour the container had f i l l e d with a red brown gas.  After this  time external cooling of the mixture, to keep the temperature below 35°C., was no longer necessary.  After 2k hours the solution (now red-brown) was  poured into 250 ml. of d i s t i l l e d water.  A white, curdy precipitate of  mannitol-1,2,U,5,6-pentanitrate immediately deposited and was filtered off after two hours, leaving a yellow-*orange solution.  Wash-water (200 ml.)  added to the main f i l t r a t e caused further precipitation but another 100 ml. used for further washing after refiltering the mother-liquor induced no precipitation. The pentanitrate product, after two crystallizations from ethanol-water, melted correctly at 8l-82°C. (27).  The yield of crude  product was 3.1 gm. (69% of theory). Determination of the Rate of Gas Evolution The reaction.was carried out in a Lunge Nitrometer equipped with a burette calibrated to read in moles x 10"^ at 20°C.  The weight of  mannitol hexanitrate used i n each case was 2.500 ~[ O.OOlgm. ' The temperature of the reaction mixture was controlled to 30 t 2°C. by means of a jacket surrounding the reaction chamber.  The mannitol hexanitrate was  placed in the cup and washed into the reaction chamber with pyridine. Evolution of the colorless gas started in three to six minutes.  The rate  of gas evolution i s plotted i n Fig. 1. Analysis of theEvpJV ed Gas A l l estimations of gas composition were done by the volumetric method using a Fischer Technical model Orsat apparatus.  The retaining  - 26 liquid was water saturated with the gas to be analysed. Results are tabulated i n Table I. After removal of the reaction mixture from the Lunge Nitrometer, the reaction chamber was rinsed and dried with acetone. A volume of commercial oxygen (approximately one half the volume of the evolved gas) was then admitted to the reaction chamber and transferred to the burette. The gas became deep brox«i in contact with the oxygen. The mercury levelling bulbs were so adjusted that mercury passed from the reaction chamber through the gas.  In about two hours the gas was  colorless, indicating complete reaction of the n i t r i c oxide with oxygen and mercury. After noting the residual volume of the gas, i t x^as tranferred to the Orsat apparatus equipped with pijopettes containing 95% ethanol, h0% potassium hydroxide and alkaline pyrogallol solutions., for absorption of nitrous oxide, fethanol and oxygen respectively. The percentage of nitrous oxide was given by a  x  V2  V where a = percent of residual gas absorbed by ethanol and potassium hydroxide = volume of gas before admission of oxygen V  2  = volume of residual gas.  The percentage of nitrogen in the gas was given by b  x  V  2  where b = percentage of residual gas unabsorbed.  - 27 The percentage of n i t r i c oaide was given by  h where c = percentage volume of gas absorbed i n alkaline pyrogallol. The original gas volume was corrected for pyridine vapor i n accordance with Van der Meulen and Mann (22). The molecular weight of the gas remaining unabsorbed after being passed through the various solutions was determined as described by Daniels, Mathews and Williams (3) •  '^he unabsorbed gas was transfer ed from  the Orsat apparatus into a previously evacuated and weighed glass bulb of known volume (11.00 ml.).  '^he pressure and temperature  of the gas i n the  bulb were recorded and the bulb then closed by means of a stopcock, wiped with a moist then a dry chamois cloth, allowed to stand i n the balance case f o r ten minutes, then weighed.  The weight and pressure of the gas  were corrected f o r the weight and pressure of water present, assuming saturation,and the molecular weight calculated from the equation M = g TR pV where M = the molecular weight. g = the corrected weight of gas T = temperature  i n degrees Kelvin  R = the universal gas constant p = the corrected pressure of the gas V = the volume. Results from several different runs were:  - 28 1.  29.3,  2.  28.7  3.  28.6  U.  29.1  5.  29.6  29.2  Fractionation of the Water Soluble Reaction Products The f i l t r a t e was concentrated under reduced pressure on the steam bath to approximately 25 ml. of clear orange liquid, transferred to a small beaker and dried in vacuo over phosphorous pentoxidee and potassium hydroxide pellets,  •'•he residue so obtained was dark orange-brown in color and  semi-crystalline, readily dissolved in cold water, dissolved almost completely i n methanol, ethanol and acetic acid, and to the extent of about three quarters in hot acetone.  It was partly soluble in chloroform  and slightly soluble in ether, benzene and petroleum ether. The residue ( 2 . 1 g ) was extracted in a WazitsfcL extractor with acetone until fresh acetone did not become colored. material was almost black and weighed 0.12g#  The undissolved  Fractional crystallization  of the extract led to the isolation of 0.02 g. of near white needles that melted at l l 5 . 5 - H 7 ° C unchanged in admixture with pure pyridinium nitrate prepared by the action of concentrated nitric acid on pyridine and purified to constant melting point (il6-117«5°C.) by recrystallization from methanol. The colored components could not be separated from the colorless crystals which appeared to make up the bulk of the residue. A portion of the residue ( 0 . 8 6 g.) was dissolved in 60 ml. of water and neutralized to pH 9 (pH paper) with 7»5 ml. of 10$ potassium  - 29 hydroxide (original pH = k)«  '^'he color of the solution changed during the  addition from orange-broim to brick-red.  distinct odor ©f pyridine was  noted. The solution was evaporated on the steam bath under reduced pressure to 25 ml. and further evaporated to dryness in a vacuum desiccator, leaving heavy red-black needles.  This residue was Insoluble in petroleum  ether, benzene and ether, slightly soluble In chloroform, more soluble in acetone, ethanol and methanol, and completely soluble in water.  On  successive extraction in a Wazitsklc extractor with acetone (yellow solution), methanol (dark red solution) and ethanol (almost colorless solution), three fractions were obtained, the major one being the acetone soluble fraction.  Fractional crystallization appeared, i n separating the  components of the acetone soluble fraction, to be no more efficient than i t had been in the case of the untreated residue and the method was abandoned. Isolation of Pyridinium Nitrate A. portion of residue weighing O.78 g. was dissolved in 50 ml. of water, heated to boiling with 1 gm. of activated charcoal, and filtered through Kiesllguhr.  The yield of ammost colorless needles obtained from  the solution after drying and recrystallizing from acetone was 0.2k g. (31$ of the weight of the residue), m.p. 115-116.2°;  m.p. in admixture  with pure pyridinium nitrate 115-5 to 117.2°. Adsorption Chromatography of the Acetone-Soluble Residue Unactivated 60-115 mesh silicagel (50 gm.) assaislurryciri acetone was introduced into a column 1.3 cm. in diameter and plugged at the constricted end with glass wool.  The height of the resulting column of  -  silicagel was 52 cm.  39  -  The column was flushed with acetone until the  effluent was clear. •• The acetone extract of 0 . 8 gm. of residue (volume 22 ml.) was added to the column and collection of 8 ml. fractions commenced. The flow-rate was 8 ml. in two and a' half minutes.  The .  separation of the fractions was detected by testing the 8 ml. portions t  of effluent with diphenylamine reagent (13) on a spot-plate.  When, •  after collection of lk5 - eight ml. portions, the portions .showed only a faint, gradually decreasing test to diphenylamine reagent, methanol was added to the  eluting; solvent in gradually increasing proportions  until acetone was eliminated completely. fractions.were obtained.  In this manner two further,  A.total of 180 - eight ml. portions of effluent  was collected, which yielded six fractions. The f i r s t was an orange-brown gummy material, the. second a very small quantity of yellow  o i l , the third  a small quantity of orange-brown semicrystalline material, the fourth .contained,, heavy light yellow needles in admixture with an orange gum, the f i f t h a light brown semi-crystalline material and the sixth an orange oil.  .  ,  .  .  Determination of Pyridine and Pyridinium Nitrate i n the fiesidue (a) Precipitation as the Copper Thiocyanate Complex (19) (i) Estimation of Pyridine.  A $0 ml. aliquot of 0.101 molar -  aqueous pyridine was treated with 7 ml..each of one molar aqueous potassium thiocyanate.and 0 . 5 molar aqueous cupric sulphate.  A green flocculent precipitate appeared which was  filtered after one hour on a fine sintered.glass funnel. precipitate was dried in -vacuo.  Yield 0.82 gm. (96%).  second run gave 0.81 g. of product (9$%)•  The A  Addition of further  precipitating reagents to the f i l t r a t e gave a white precipitate presumably of copper thiocyanate. , (ii)l)Estimation of Pyridine in Pyridinium Nitrate.  A solution of  0.58 gm.- of pyridinium, nitrate dissolved in 100 ml. of water was neutralized to pH 10 (alkacid paper).  The pyridine-water  azeotrope was d i s t i l l e d off under reduced pressure in an a l l glass apparatus into a. 100 ml. receiver cooled in a brine bath at -10°C.  T'he receiver was backed up by a dry ice trap.  The contents of the receiver and.trap were washed into a beaker and the pyridine estimated by precipitation as the- copper thiocyanate. complex.  The yield was 80$.of theory.-  Two  repetitions of this procedure gave yields of 91.3$ and 91*3$ ' of. theory.  .  „  . \  (b) Precipitation as Pyridinium Perchlorate ' To Of62 gm. of. pyridinium nitrate dissolved in 10 ml. of glacial r  acetic acid was added a I N .  solution of perchloric acid in acetic  acid until precipitation of the white pyridinium perchlorate :  :  was  complete. , The precipitateuwas filtered and dried i n vacuo. gm.  (98$).  About. 0 . 7 gm.  Yield 0.75  of residue.was dissolved.in 10 ml. of  glacial acetic acid, filtered from a very small quantity of mediumbroxm insoluble material and treated with 1 N. perchloric acid in glacial acetic acid.  i  he  solution was made up to 125 ml. with ether  to induce further precipitation.' ^he precipitate was filtered and dried in vacuo.  Yield 0.73 g. of heavy yellow needles.  liquor was yellow in color. ,  . .  . '  The mother  -' 32 «  The precipitate was dissolved in 100 ml. of glacial acetic acid and treated with 7 ml. of 10$ potassium acetate in glacial acetic acid.  The fine white precipitate of potassium perchlorate was •  filtered off and the solution evaporated under reduced -pressure. The solid material remaining was part white, 'part brown powder.' -' ;  The white material probably was potassium acetate. The f i l t r a t e from the perchlorate precipitation, after precipitation of excess perchlorate with potassium acetate in acetic* acid, was concentrated under reduced pressure and dried in vacuo.  The solid, light brown residue was extracted with  acetone until the remaining solid was almost colorless, ^he acetone solution was evaporated to dryness (the last stage in  •  vacuo) leaving 0 . 1 gm. of dark orange-brown amorphous hyirescopic • .material, which was then chromatographed  on paper (Table II).  (c) Separation by Dialysis  ...  (i) Dialysis of Pyridinium -Nitrate-.  A. dialysis' bag was • charged -\ :•.  with 1 gm. of pyridinium nitrate in 100'ml. of water and 'the whole suspended in a beaker.cl' Mater was constantly admitted to the beaker from the bottom. '  In a twenty-four hour period the  solution in the'dialysis bag gave a negative test-for nitrate to diphenylamine reagent and had no pyridine odor.  ('ii)Dialysis of the Residue.  A solution of 0 . 8 gm. of residue in  100 ml. of water was dialysed In a liquid-liquid extractor. The color of the solution in the bag did not appear to diminish but the extracting liquid'became yellow-orange.  After twenty--  four hours no more color was extracted - from the bag, the contents  - 33 -  of which gave a negative test to diphenylamine reagent.  Both  bag contents and dialysing solution were reduced to solid • residues by the usual procedure.  The bag residue weighed  0.01 gm., was dark brown in color and d i f f i c u l t y soluble in water,  -he solid from the dialysing solution was light •  orange-brown in color and had more crystalline character than the original residue.  It could be separated, by extraction  with acetone, into a partly crystalline yellow-orange  acetone  •soluble fraction and an orange-brown amorphous material, (d) Separation by Ion Exchange (i) Preliminary Tests.  In preliminary tests, Amberlite I-R-l^B;,  anion exchange resin was found to "throw" i t s color badly and so was substituted with Amberlite I-R-l+5. • ' Approximately 20 gm. (damp) of Amberlite -l-R-k$ anion • exchange resin was stirred for twenty minutes with a solution of one gram of pyridinium nitrate dissolved in 100- ml. of water.  The mixture was then filtered on a coarse sintered  glass funnel and the resin-washed with water-.  The resin was  then regenerated by washing with •$% NaHCO^ (200 ml.) and then water until the washings were neutral to pH-paper.  Filtrate  and resin were then recombined and the process repeated twice. After two treatments the solution gave only a faint test with diphenylamine reagent and the third treatment had no noticeable effect. ( i i ) Treatment of the Residue with Amberlite I-R-U5 Resin.  A  portion of the resin (0.68 gm.) was treated in the. pr eceeding  -•34manner except that the sodiym bicarbonate regenerating solution was saved since i t was yellow i n color.  On the  third regeneration the -regenerating solution was not colored. The treated solution was evaporated to dryness, leaving a hard, amorphous, f a i r l y dark orange-brown residue weighing 0.11 gm.  The combined regenerating solutions were reduced  to dryness.  The solid residue (mostly sodium bicarbonate)  was then extracted with acetone until i t was colorless.  On  evaporation of the acetone, 0.32 gm. of very dark brown material was obtained.  The crystalline character appeared  to be attributable to colorless crystals of sodium bicarbonate.  In any case, the dark material'was only.a very small  part of the total. (e) Titrimetric Determination (i) Preliminary Tests.  A, 250 ml. aqueous solution was  prepared,  containing 1.31*0 gm. of pyridinium nitrate and 17*55 gm. of pyridine.  Aliquots of 25 ml. of this solution were.titrated  f i r s t with standard 0.2 N. potassium hydroxide from a 5 ml. burette for estimation of nitrate, and then with standard 0.6 N Sulfuric acid for estimation of total pyridine (free pyridine added plus pyridine freed from pyridinium nitrate).  The end .,  points were detected with the ..aid of a Beckman model "G" pH meter equipped with a standard glass electrode and a. fibretipped calomel electrode containing saturated potassium chloride solution.  The end point in the potassium hydroxide  titration occured at a pH of about 9*2 with a maximum change  -35in pH per drop of potassium hydroxide solution (0.033 ml.) of about 0.35 pH units.  ^he end point i n the titration  with sulphuric acid occured at a pH of about 3.05 with a maximum change inpH per four drops of sulphuric acid solution (0.20 ml.) of about 0.16 pH units. he determined T  weight of pyridinium nitrate was 0.131+3 (100.2$) and 0.131+7 gm. (100.1+$). The determined weight of pyridine (actual weight- was 18.2 gm.) was 18.1 gm. and 18.1.gm. (99*5$)• The pyridine lost in manipulation of the reaction mixture was determined as followss Pyridine (15 ml.) was subjected to the entire procedure of the denitration aid preparation of the aqueous reaction products for titration.  ^he theoretical weight of pyridine  titratable then should be 17.7 gm.  The result's were as  follows: Run 1 .  17.52  Run 2.  17.52  17.1+9  17.52  17.1+8  17.59  average = 17*1+9  average = 17.51+  = 17.5  pyridine lost = 0.2 gm. (1.1$)  = 17.5' * 0.2 gm. (1.1$).  deviation between the results of the txiro runs i s 0.05 ml. (0.28$). ( i i ) Volumetric Analysis of the Water Soluble Reaction Products. The denitration reaction was carried out as usual i n  '  - 36 .-  the Lunge Nitrometer.  Special care was taken in handling the  pyridine and the reaction mixture to prevent loss in maniptte lation.  The reaction was allowed to proceed for four hours  and the rate of evolution of the gas was recorded... After transferring the reaction mixture to a 25>0 ml. groundglass stoppered erlenmeyer flask containing 200 ml. of water, the reaction chamber was rinsed with three one-ml. portions of pyridine delivered from a one-ml. pipette and then with 10 ml. of water in three ^portions. t  The mixture was then allowed to  stand for at least two hours, the precipitate of pentanitrate was filtered and washed on a previously weighed course sintered glass funnel and,the f i l t r a t e transfered to a 2J?0 ml. volumetric flask, and diluted to the mark.  Twentyfive ml.  aliquots of this solution were then titrated as described in the preceding section.  One 25 ml. aliquot was treated with  a measured excess of potassium hydroxide and evaporated to dryness in a desiccator for determination of the weight of residue.  '^he results are tabulated in Table III.  - 37 -  BIBLIOGRAPHY 1 . Angeli, A.  17:113.  Z. ges. Schiess-Sprengstoffw.  2 . Beatty, R.L., Burger, L.B. and-Schrenk, H.H. 3687.  Rept. Investigations.  U.S. Bur. Mines.  Feb. 1 9 4 3 .  3 . Daniels, F., Mathews, J.H. and Williams, J.W. Chemistry. Ii. Divers, E.  McGraitf-Hill Book Co.  6 . Gladding, E.K., and Purves, C.B.  1949.  J. Am. Chem. Soc.  1 3 . Mulliken-Huntress. M.I.T. 14.  16:766.  1944.  Trans. Sci. Inst. Fertilizers (Moscow)  CA. 2 7 : 5 8 9 9 .  1946.  1944.  1951.  1943.  The Chemistry of Heterocyclic Compounds.  Book Company.  1921;.  University of British Columbia. 1 9 5 2 .  M.Sc. Thesis.  1 1 . Mirkin, I.A., and Glazova, L.V.  1 2 . Morton, A.A..  73:1974.  Ind.Eng. Chem., Anal. Ed.  1932.  18:2810.  McGill University.  8. Hayward, L.D.  No. 9 2 : 1 1 7 .  CA.  66:76.  Ph.D. Thesis.  10. McKeown, G.G.  1921..  J.Am.Chem. Soc.  7. Hayward, L.D.  9 . Kieselbach, R.  1899.  54:79-  Gazz. Chim. I t a l .  Experimental Physical  194l. p.3.  75:82.  Chem. Soc. Trans.  5 . Giannini, G.  1922.  McGraw-Hill  p.192.  Manual of the Identification of Organic Compounds.  1937- p . 1 6 3 .  Patterson, T.S., and Todd, A.R.  1 5 . Rooney, C.S.  Ph.D. Thesis.  16. Ryan, H., and Casey, M.T.  J . Chem. Soc. 2876.  McGill University.  1929*  1952.  Scien. Proc. Royal Public Soc. 1 9 : 1 0 1 .  1928-1930. 17*  Scott, W.W.  Standard Methods of Chemical Analysis.  Company Inc. 1 8 . Segal, G.H.  D. Van Nostrand  p. 2346.  Ph.D. Thesis.  McGill University.  1946.  


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