1206
relatively inefficient deactivator in alkaline solution; yields of hydrazine were negligible. Glycylglycine is somewhat better, but glycylglycylglycine, one of the simplest polypeptides is practically as effective as gelatin. For triglycine one can envisage the formation of a quadridentate copper complex. Proposed structures are given in Figure 3. +I
H2 *
Vol. 47,No. 6
INDUSTRIAL AND ENGINEERING CHEMISTRY
H
ACKNOWLEDGMENT
This investigation was carried out under the sponsorship of the Office of Ordnance Research, Contract DA-11-022-ORD-828, and also aided materially by a research grant t o R. W. Sanftner from the Western Cartridge Co., Division of Olin Industries, Inc., East Alton, Ill. Our thanks are also extended t o the following companies for furnishing samples €or evaluation: Seaport Chemical Coip., 63 David St., h-ew Bedford, Mass. Kelco Company, 20 S o r t h Wacker Drive, Chicago 8, Ill. Bersworth Chemical Co., Framingham, Mass. Alrose Chemical Co., 180 Mill St., Cranston, R. I. LITERATURE CITED
0
Figure 3. Proposed structures for copper(I1) complexes A . Glycine B . Glycylglycine C . Glycylglycy1:lycine
It is also quite probable t h a t the alginic acid and carrageenin derivatives used in the present investigation serve as complexing agents rather than as adsorbents. Simple polyhydroxy-carboxylic acids, such a s tartaric acid, have long been recognized as substances which form complexes that are relatively stable in alkaline solution. Traube and coworkers (19) have shown t h a t the more complex sugars and sugar acids function in a similar manner. Addition of magnesium ion t o the alkaline synthesis solutions t o form either the hydroxide or the silicate constitutes a n effective method for deactivating dissolved copper; whereas, addition of calcium, barium, cadmium and zinc ions t o synthesis solutions containing silicate serves no beneficial purpose. The siz;es of the ions may be a pertinent consideration. The ionic radii in Angstrom units of M g + + (0.65) and C u + + (0.69) are practically identical which means t h a t these two ions of the same charge could replace each other in their respective lattices. The radii of the alkaline earth ions are larger ( C a + + , 1.06; B a + T , 1.44) making such isomorphous coprecipitation improbable.
Audrieth, L. F., and RIohr, P. H., IND. ENG.CHEX, 43, 1774-9 (1951). Audrieth, L. F., and Ogg, B. A., “Chemistry of Hydrazine,” pp. 28-36, Wiley, New York, 1951. Cederquist, K. Ti., Swedish Patent 115,217 (October 23, 1945). D’Ans, J., and AIattner, J., Angew. Chem., 64,448-52 (1952). Joyner, R. d.,J . Chem. SOC.,1923, pp. 114-21. Joyner, R. A., U. S. Pat& 1,480,166 (Jan. 8,1924). Kanao, S., and Igi, S., Japanese Patent 174,913 (June 24, 1948). Malatesta, L., Gam. chim. ital., 71,467-74 (1941). Ibzd., pp. 5804. M$ller, M., Kgl. Danske Videnskab. Mat.-fus. M e d d . , 12, h’o. 16 (1934). h-agasawa, S., C h m . Researches ( J a p a n ) 5, Inorg. and AnaE. Chem., 19-34 (1949). Tiagasawa, S., J. Chem. Soc. J a p a n , Pure Chem. Sec., 69, 17 (1948). Ibid., p. 72. Penneman, R. A., and Budrieth, L. F., Anal. Chem., 20, 1058-61 (1948). Pfannmuller, W., Traud, W., and Wintersberger, J., German Patent 735,321 (April 8, 1943). Pfeiffer, P., and Simons, H., Ber., 80, 127-8 (1947). Raschig, F., “Schwefel und Stickstoffstudien,” Verlag Chemie, G.m.b.H., Leipzig and Berlin, 1924. Thdnnessen, K., German Patent 729,105 (Nov. 12, 1942). Traube, W., and Kuhbier, F., Ber., 69, 2655-63 (1936). Troyan, J. E., IKD. ESQ. CHEM., 45,2608-12 (1953). RECEIVED for review December 20, 1954.
$CCEPTED
%7
February 21, 1955.
Hvdrazine from Semicarbazide Solvolvsis J
u’
GEORGE W. WATT AND JOSEPH D. CHRISPl The University of Texas, Austin, Tex.
T
HERE are two possible methods for the formation of hydrazine from semicarbazide and both have been considered as bases for the development of practical processes. One of these involves liberation of hydrazine by hydrolysis in either acidic or basic mediums; t h e latter is disadvantageous owing t o the instability of hydrazine in the presence of strong bases ( 7 ) . Hydrolysis in the presence of dilute sulfuric acid, for example, would yield hydrazine sulfate from which the free base could be liberated b y treatment with anhydrous liquid ammonia ( 2 ) . Since ammonium sulfate is substantially insoluble in liquid ammonia (4),filtration followed by evaporation of the solvent ammonia should provide essentially anhydrous hydrazine. Harlay (9) has shown t h a t hydrazine hydrochloride results when semicarbazide is treated with 4 N hydrochloric acid in a sealed tube for 18 hours, Lieber and Smith (11) have studied the hydrolysis of semicarbazide in both acidic and basic mediums but their objective was not the production of hydrazine. The ammonolysis of hydrazine sulfate with liquid ammonia has been studied by Browne and coworkers (5, 6). who reported the pro1
Present address, Eastern Laboratory, Explosives Dept., E. I. du Pont
de Nemours t Co., Gibbstown, N. J.
duction of hydrazine of 93.Zy0 purity, and by Friedrichs (8) who reported yields of 90 t o 96%. More recently, work in these laboratories has shown that this reaction provides a 99% yield of hydrazine of essentially 100% purity (16). The other and somewhat more attractive approach lies in a potentially closed cycle process, one step of which involves the direct ammonolysis of semicarbazide with liquid ammonia t o form hydrazine and urea. Following separation of the hydrazine and t h e solvent, the urea could be recycled t o the steps required t o produce semicarbazide from urea-Le., the formation of urea nitrate, its dehydration of nitrourea, and subsequent reduction to semicarbazide. These latter steps are well known, but t h e literature provides no information relative t o the ammonolytic cleavage of semicarbazide. T h e work described in the present paper is concerned primarily with a detailed study of the ammonolysis of semicarbazide with liquid ammonia. Also included are the results of a brief study designed t o establish conditions favorable t o the formation of hydrazine sulfate from semicarbazide by hydrolysis with dilute sulfuric acid; t h e ammonolysis of hydrazine sulfate will be described elsewhere (16).
”
INDUSTRIAL AND ENGINEERING CHEMISTRY
June 1955
ANALYTICAL .METHODS
All determinations of hydrazine, urea, and semicarbazide (either as starting materials or as equilibrium mixtures of reaction products) employed methods t h a t have been described previously (14, 16). These methods provide for the spectrophotometric determination of hydrazine and urea, and for the determination of semicarbazide by titration with iodate. MATERIALS
Hydrazine dihydrochloride (Eastman No. 1117) was found t o contain 99.8% NzH4 2HC1. Similarly, the purity of semicarbazide hydrochloride (Eastman No. 226) was found to be 99.4%. Semicarbazide, m.p., 95' C., was prepared from the sulfate as described by Audrieth (1). All other chemicals used were reagent grade products t h a t were dried but not otherwise purified before use. HYDROLYSIS OF SEMICARBAZIDE
I n a typical case, 3.0 grams of semicarbazide hydrochloride in 30 ml. of 6 M sulfuric acid were refluxed for 0.5 hour. T h e reaction time was taken as the interval between complete solution of the salt t o the withdrawal of the source of heat. The reaction mixture was allowed to cool t o room temperature, then was cooled in a n ice bath. T h e resulting crystals of hydrazine sulfate were separated by filtration within 2 hours (on longer standing a t 0 O C., unchanged semicarbazide also crystallizes as the sulfate), washed with cold 1M sulfuric acid, washed with absolute alcohol, and dried t o constant weight a t 140" C. Yields thus determined were checked by direct spectrophotometric determination of hydrazine ( 1 4 ) ; the results were in uniformly good agreement. T h e results of experiments in which three different variables were studied are given in Table I.
Table I.
Hydrolysis of Semicarbazide with Sulfuric Acid Hydrazine Yield, %
Reaction Time, Hr.
3 M HzS04. mi. 15 30
6.M HzSOa, ml. 15 30
1207
ammonia were identified. Hydrazine was identified as benzalazine, m.p., 93" C., and by comparison of the spectral curves obtained in the spectrophotometric determination of hydrazine ( 1 4 ) with the spectral curves for pure hydrazine a t different concentrations by plotting the logarithm of optical density against wave length. Urea was similarly identified by comparison with spectral curves for urea (16). Unchanged semicarbazide was identified as the benzaldehyde semicarbazone, m.p., 218" to 220" C. All efforts to detect reaction products other than urea and hydrazine were unsuccessful. Table IJ. Influence of Temperature and Ammonium Chloride Concentration on Hydrazine Yields from Semicarbazide Ammonolysis Temp., OC. 25 75 90
"4C1/ CH6ONs
105
Yield, 97, 0 22 33 .. 39 37 43
17 48 44
123
49
Effect of Temperature. T h e yield of hydrazine as influenced by temperature and ammonium chloride concentration was determined using semicarbazide, semicarbazide hydrochloride, and the latter plus added ammonium chloride as starting materials; the resulting d a t a are given in Table 11. Attention is called to the fact t h a t use of semicarbazide hydrochloride in liquid ammonia is equivalent t o using the free base and ammonium chloride in a I : 1 mole ratio. I n Table I1 and elsewhere, the specified ratios of ammonium chloride to semicarbazide, CHbON3, include the ammonium chloride resulting from use of semicarbazide hydrochloride as a starting material. Effect of Time. Since the yield of hydrazine was not increased appreciably by increasing the temperature above 105" C., the influence of reaction time a t different ammonium chloride concentrations was determined a t 10.5' C. using semicarbazide hydrochloride in all cases. I n addition t o the data given in Table 111, it was found t h a t hydrazine is not formed over 30 hours a t 25 O C., and that the hydrazine yield is 41% for a reaction time of 6 hours at 123O C. and mole ratios of ammonium chloride to semicarbazide equal to 1: 1 and 3 : 1 .
AMMONOLYSIS OF SEMICARBAZIDE
The equipment and procedures employed in this work were essentially the same as those described by Watt and Post ( 1 7 ) . Unless otherwise indicated, the reactions were carried out under strictly anhydrous conditions in sealed tubes in an autoclave for 13 hours a t 105" C. and involved 1.5 grams of semicarbazide hydrochloride in sufficient liquid ammonia to provide a total solution volume of 25 ml. a t -70" C. On completion of a run, the tube was cooled t o -70" C., opened, the solvent allowed to evaporate, and finally warmed t o room temperature. The residue was dissolved in water, made slightly acidic by addition of dilute hydrochloric acid, and made up to a known volume from which aliquots were taken for analysis. Preliminary Experiments. Since it was planned to study the ammonolysis of semicarbazide a t temperatures above its melting point (96" C.), i t was necessary a t the outset t o determine whether hydrazine is formed by the pyrolysis of semicarbazide. Accordingly, semicarbazide hydrochloride was heated in a sealed tube under the conditions specified; hydrazine was not produced. T h e same result was obtainedwhen ammonium chloride and semicarbazide in a 2 : 1 mole ratio were treated similarly. When the free base alone was used, hydrazine was formed but in yields of only 3 i 1%. T h e products of the ammonolysis of semicarbazide with liquid
Table 111. Influence of Reaction Time and Ammonium Chloride Concentration o n Hydrazine Yields from Semicarbazide Ammonolysis Time, Hr. 1 3 6
8 5 13 24
NHaCl/ CHsONa
Yield,
1 1 1
3
24 33 39 39
3
40
1 1
2 3 1 3
%
40
43 47
48 44 51
Effect of Other Salts. I n order t o study further the effect of ammonium ion concentration as well as t o detect possible catalytic effects of specific anions, reactions were carried out using added ammonium chloride, bromide, nitrate, and sulfate, and sodium chloride. Since semicarbazide hydrochloride was used in these runs, ammonium chloride was present in all cases. I n series of separate experiments, the salts were added in mole ratios that ranged from 2 to 5 moles per mole of semicarbazide hydrochloride. The hydrazine yields ranged from 43 to 52% and showed no regular dependence on either the identity or concen-
1208
INDUSTRIAL AND ENGINEERING CHEMISTRY
tration of the added salt; sodium chloride yielded the same results as ammonium salts. Effect of Ammonia to Semicarbazide Ratio. As shown by Table 111, the yield of hydrazine produced in 13 hours a t 105’ C. is 43y0 under conditions such t h a t the mole ratio of ammonia t o semicarbazide is 74:l. When this ratio was reduced to 18:1, the yield of hydrazine was 26%. Synthesis of Semicarbazide from Hydrazine and Urea in Liquid Ammonia. Since, in the ammonolysis of semicarbazide with liquid ammonia, equilibrium is established after 13 hours a t 105’ C., the reverse reaction was demonstrated as follows. Hydrazine dihydrochloride (0.0135 mole) and urea (0.0136 mole) in 25 ml. of liquid ammonia were heated for 13 hours at 105’ C. Analysis of the resulting reaction mixture for semicarbazide (which was identified as the benzaldehyde semicarbazone) and for unchanged hydrazine and urea revealed Semicarbazide Unchanged hydrazine Unchanged urea
Mole 0.0058
0.0077 0.0082
Thus, essentially 100% of t h e starting materials was accounted for, and substantially identical results were obtained in duplicate experiments During the first attempts t o obtain complete analytical data for these reactions as well as t h e ammonolysis of semicarbazide, the quantities of hydrazine were consistently 5 t o 7% lower than the corresponding values for urea. This suggests loss of hydrazine owing t o either decomposition of hydrazine during the course of the reactions or covolatilization of hydrazine during evaporation of the ammonia a t the end of the runs. I n order to evaluate the total loss of hydrazine, a quantity of hydrazine dihydrochloride corresponding t o a 50y0 yield of hydrazine from a typical ammonolysis run was heated in 25 ml. of liquid ammonia solution for 13 hours a t 105” C., the ammonia was evaporated, and the residue was analyzed for hydrazine. Of the hydrazine used as the dihydrochloride 5% was lost during the course of the experiment. To determine what fraction of this loss is attributable t o covolatilization with ammonia, the experiment was repeated except t h a t the hydrazine salt was simply put in solution in ammonia by heating t o 8 5 ” C. for 10 minutes, and then the ammonia was evaporated immediately. Analysis for hydrazine showed that in this case 3.6% of the hydrazine was lost. Accordingly, the data reported for hydrazine recovered in the experiments in which semicarbazide was formed from urea and hydrazine were corrected to the extent of +5%. This correction was used in all cases involving complete analysis of reaction mixtures but not otherwise. Equilibrium Constants. I n similar experiments, the ammonolysis of 0.0135 niole of semicarbazide was found to yield
.
Hydrazine TJrea Unchanged semicarbaside
Mole 0.0064 0.0068 0.0071
which accounts for essentially 100% of the semicarbazide used. The equilibrium constant for the ammonolytic reaction computed from these data is 6.2 X 10-3; t h a t for the reverse reaction, the reciprocal of computed from the data given, is 1.1 X which is 9.1 X 10-8. Similarily for the ammonolytic reaction at 75” C., the equilibrium constant was 1.3 X while for the same reaction at 105’ C. and an ammonia to semicarbazide ratio of l S : l , the value for the equilibrium constant was 9.0
x
10-8. DISCUSSION
T h e data show t h a t hydrazine as the sulfate may be produced in substantially quantitative yield by the hydrolysis of semicarbazide hydrochloride using 10 ml. of 6 M sulfuric acid per gram of semicarbazide hydrochloride ( CHeONaC1) under reflux for 1 hour. As is shown (16), this salt after thorough drying may
Vol. 47,No. 6
be quantitatively ammonolyzed with liquid ammonia t o provide essentiallg anhydrous hydrazine. The ammonolysis of semicarbazide with liquid ammonia ,
NHzC(=O)IYHNHz
+ NHa e NHzNH2 + NH&(=O)NHz
both in the presence and absence of ammonium chloride (an acid in liquid ammonia) or other ammonium salts has been shown to be reversible. Equilibrium is established after 13hours a t 105 C. and the hydrazine present at equilibrium cannot be attributed t o pyrolysis. Currently, means are being considered for t h e displacement of this equilibrium with resultant complete ammonolysis. For example, it is planned t o carry out this reaction in the presence of metal salts which form coordination compounds with hydrazine (a), thus providing for the progressive removal of hydrazine as ammonia-insoluble hydrazinates from which anhydrous hydrazine might be recovered by thermal decomposition a t low pressures and relatively low temperatures. I n connection with the synthesis of semicarbazide from urea and hydrazine in liquid ammonia, it should be recognized t h a t Mistry and Guha (19) have carried out this same synthesis i n amyl alcohol at its boiling point. Although the conversions in the presence of ammonium salts were measurably but not markedly greater than in the absence of such salts, i t must be concluded t h a t this ammonolysis is not appreciably acid-catalyzed. Since the effect of added sodium chloride was almost exactly the same as t h a t of ammonium chloride, this case may constitute another example of electrolyte catalysis ( I O , IS) of an ammonolytic reaction. O
ACKNOWLEDGMENT
The work described in this paper was supported by the United States S a v y , Bureau of Ordnance, under Contract, N123s-67363, Task Order 11. The liquid ammonia used in these studies was generously supplied by the Polychemicals Department, E. I du Pont de Nemours & Co. LITERATURE CITED
Audrieth, L. F., J . Am. Chem. SOC.,52, 1250 (1930). Audrieth, L. F., and Ogg, B. A., “Chemistry of Hydrazine,” D. 52. Wilev. - . New York. 1951. Ib;d., p: 181. Bergstrom, F. W., J . Phys. Chem., 29, 160 (1925). Browne, A. W., and Houlehan, A. E., J . Am. Chem. SOC.,33, 1734 (1911). Browne. A. W.. and Welsh. T. W. B.. Ihid.. 33. 1728 (1911). Clark, C. C., “Hydrazine,” p. 2, Mathieson ‘Chemical Corp., Baltimore, Md., 1953. Friedrichs, F., J . Am. Chem. Soc., 35, 244 (1913). Harlay, V., J . pharm. chim., ( 8 ) , 23, 199 (1936). Lemons, J. F., Williamson, P. At., Anderson, R. C., and Watt, G. W., J . Am. Chem. SOC., 64, 467 (1942). Lieber, E., and Smith, G. B. L., Ihid., 59, 2283 (1937). Mistry, S. M., and Guha, P. C., J . Indian Chem. SOC.,7, 793 (1930). Roper, W. F., Anderson, R. C., and Watt, G. W., J . Am. Chem. SOC.,67, 2269 (1945). Watt, G. W., and Chrisp, J. D., Anal. Chem., 24, 2006 (1952). Ihid., 26, 452 (1954). Watt, G. W., and McBride, W.R., J . Am. Chem. Sac., in press. Watt, G. W., and Post, R. G., IND.EXG.CHEM., 45,846 (1953). RECEIVED for review October 25, 1954.
ACCEPTED February 23, 1955.
