LIQUID AMMONIA AS A SOLVENT AND THE AMMONIA SYSTEM OF COMPOUNDS. VI. ORGANIC AMMONIA COMPOUNDS. PART 111. MIXED ACIDS AND THE AMMONIA ACIDS OF NITROGEN' W. C o ~ m %RNELNS, TFIB OHIO STATEUNIVERSITY, COLUMBUS, OHIO, AND WARREN C. JOHNSON, UNIVERSITY OF CHICAGO, CHICAGO, ILLINOIS
The earlier.portions of this paper2 were concerned with the nitrogen analogs of the familiar oxygen alcohols, aldehydes, carboxylic acid and carbonic acids. There remains to consider certain mixed componndsderivatives at the same time of water andiof ammonia; the disnbstituted ammonia derivatives such as benzene sulfonnitramide, CaHsS02NHN02; and the ammonia acids of nitrogen.
Mixed Aquo-Ammono Acids The Carbylic Acids.-In order to have some term a t once descriptive of the carboxylic, carba~ylic,~ and similar acids, derivatives of the group RC=, Dr. Franklin has suggested "carbylic acid." The substances presented by the following formulas
are, respectively, an aquo, an ammono, and a thio carbylic acid. The acid
, being derivatives at the same amides, substances of the type RCO' \NH~ time of ammonia and water,
may rightly be regarded as mixed aquo-ammono carbylic acids or carboxazylic acids.' As acids, the acid amides conduct the electric current and affect indicators when dissolved in liquid ammonia5 and by their
'
Previous articles in this series have appeared as follows: I, Tnrs JOURNAL, 5, 664 (June, 1928); 11, Ibid., 828 (July, 1928); 111, Ibid., 6, 20 (Jan., 1929); IV, Ibid., 441 (March, 1929); V, Ibid., 7,98149 (May, 1930); VI, Part I, Ibid., 1291-9 (June, 1930); VI, Part 11,Ibid., 1602-16 (July, 1930). '(a) Ibid., 7, 981-99 (June, 1930); (b) 1602-16 (July, 1930). a Ref. 2b. p. 1603. 'In the early literature, before the organic side of the ammonia system was adequately developed, the carboxazylic adds were erroneously styled simply ammono acids. See Franklin, J. Am. Chmt. Soc., 46, 2147 (1924). "a) Franklin and Kraus, Am. Chem. J., 23, 277 (1900); (b) J. Am. Chmt. Soc., 27, 191 (1905). 1850
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action upon both ammono bases and metals fonn numerous which conduct the current with a much greater facility than the acids.9 As carbylic acids these compounds are converted into carboxylic acids and carbazylic acids by hydrolysis and ammonolysis, respectively.
The potassium derivative of palmitamide, a mixed aquo ammono soap, behaves like a soap when dissolved in liquid ammonia in that it lowers the surface tension causing foaming.1° Just as acetonitrile reacts with potassium amide in liquid ammonia to fonn a salt of a carbazylic acid so acetonitrile reacts with potassium hydroxide in the same solvent to form a salt of a mixed aquo-ammono acetic acid,"
+ KNH* +CHC(NH)NHK + KOH CH8C0.NHK
CHsCN CHCN
--t
The pyrogenic decomposition of the salts of the carboxazylic acids yields methane and sodium cyanate," a salt of a mixed aquo ammono carbonic acid, exactly as salts of the aquo and ammono carbylic acids yield methane together with sodium aquo carbonate and sodium ammouo carbonate, respectively.
+ + +
CHGONHNa +CHI NaNCO NaOH +CHI Na2CO8 CH.COONa CHaCNHNHNa NaNH2+CH. NarCN2 NHsLa
+
+
+
Esters of the carboxazylic acids may be either nitrogen or oxygen substituted. In either case ammonolysis of these esters yields the expected substances,
(a) Franklin and Stafford, Am. Chem. 3..28, 83 (1902): (b) Franklin, 81h I d . Cong. A$$. Chem., 6, 119 (1912); (6) 3.Am. Chem. Soc., 37, 2279 (191.5). ; Numerous salts of ammono and mixed aquo ammono acids that have been prepared, yet in no case (with the single exception of cyanamide and possibly malonamide) has i t been possible t o replace more than one hydrogen atom of the amino group, -NH2. Thus RCONH. is a monobasic acid and its salts are binary electrolytes. It is interesting t o note that the mercury and silver salts of the acid amides are stable in water solution. Because of the tenacity with which nitrogen clings to some metals such as silver and mercury, Dr. Franklin has termed these metals "azopbiles," lovers of nitrogen. *Smith, 3. Am. Chem. Soc., 49, 2162 (1927). '"Fuon (Miss), Dissertation, Stanford University, 1925. Cornell, J. Am. Chem. Soc., 50, 3311 (1928). Cf. Ref. 2b, p. 1610. Miss Fulton (Ref. 10) noted that there is also a decomposition of potassium benzamide t o nitrile and potassium hydroxide. la Niemam, Thesis, Stanford University, 1926, " Pinner, Ber.. 16, 1643 (1883).
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Furthermore, the acid esters are known to form salts." Other types of mixed carbylic adds are RCS.OH and RCS.NH2. A further type of mixed acid closely related to the carbylic acids is benzene sulfonamide, a mixed aquo ammono benzene sulfonicacid. Numerous salts of acids of this type have been ~ r e p a r e d . ~ " ' ~ Mixed Aquo-Ammono Carbonic Acid@ Proceeding to a consideration of the important mixed aquo-ammono carbonic acids it will be clear that as the formulas C(OH)4and C(NHp)4 represent, respectively, the ortho aquo and ortho ammono carbonic acids, so the three intermediate formulas given in the table are purely hypothetical formulas for mixed aquo-ammono orthocarbonic acids.
Since dehydration (loss of water) and deammonation (loss of ammonia) are strictly analogous phenomena, it is obvious that the elimination of the elements of water or ammonia or of both water and ammonia from the respective mixed aquo-ammono carbonic acid formulas will yield formulas which will be recognized as those of carbamic acid, urea, and cyanic acid. Furthermore, the strong tendency toward the formation of pyro acids and toward polymerization into six-membered rings gives rise to a large number of other mixed aquo-ammono acids. Biuret, triuret (carbonyl urea), and cyanuric acid are examples of such compounds. OH OC
NH,
OC Biuret
NH2 Triuret
I
C ! i N'
I
HO--C
-.
/I
C-OH
\w/
Cyanuric Acid
' T h e mixed quo-ammono carbonic acids are discussed in the following papers where complete references are given: Franklin, I. Am. Chem. Soc.. 46, 2148 (1924): Blair, Ibid., 48, 87, 96 (1926); Pinck and Blair. Ibid.. 49, 509 (1927).
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In support of the view that these substances are mixed aqua-ammono carbonic acids, the following facts are offered: first, carbamic acid and cyanic acid are familiarly known to form salts. In liquid ammonia carbamic acid reacts with an excess of potassium amide to form a dipotassium salt. Second, urea, although too weak an acid to form salts in the presence of water, reacts in liquid ammonia solution with potassium amide to fonn a mono- and dipotassium salt and also with metallic magnesium to form a magnesium salt. Biuret similarly forms a mono- and tripotassium salt in liquid ammonia and triuret a mono- and tripotassium salt in liquid ammonia and triuret a mono- and dipotassium salt. Third, all of the aqua-ammono carbonic acids mentioned above and numerous others, when heated in water, on the one hand, are hydrolyzed to carbon dioxide and ammonia and, when heated in liquid ammonia, on the other, are ammonolyzed to guanidine. Finally, when fused with an excess of sodium amide these mixed acids are converted into sodium ammono carbonate, sodium cyanamide. Esters of mixed aquo-ammono carbonic acids are saponified to the correspondmg alcohols and acids as is illustrated by the ammonolysis of diphenyl urea,ls OC(NHCsH&
+ 2NHa +ZCeHsNH* + OC(NH&. Further Mixed Acids
When acetyl chloride and sodium acetate are permitted to react, acetic anhydride is formed, CHICOCI
+ NaOOC-CH, +NaCl + CHC&O-COCH8
If sodium nitrate is substituted for sodium acetate, then a substance, acetyl nitrate, is formed which is a t the same time the anhydride of acetic and of nitric acids since both of these acids are formed when the anhydride reacts with water,
+
+
CHsCOCl NaONO2 +NaCl CHaCO---NOn H 2 0 -+CHCOOH HONO*. CHsCO--0-NO2
+
+
Similarly, acetyl chloride and sodium azide form acetyl azide CHCOCI
+ NaNNz +CH,CO--N=N=N
f NaCI.
This compound, depending upon whether one is considering its reaction with water or with ammonia, may be regarded either as the anhydride of aqua-acetic acid and ammono nitric acid or as the anammonide of mixed aqua-ammono acetic acid and ammono nitric acid, CHsCO.N=NeN CHICO N = N E N
+ H 2 0--+ CHCOOH + HNNz. + NH1+CHICONH~+ HNN*.
Consider benzene sulfonylchloride. If it reacts with water benzene sulfonic acid is formed; if it reacts with ammonia benzene sulfonamide is formed.
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This .latter substance is an acid in liquid ammonia since its solution in that solvent is a good conductor of the electric ~urrent.'~Furthermore, benzene sulfonamide in ammonia solution forms salts with ammono baseseC and attacks metals with the evolution of hydrogen gas. It is rightly called a mixed aquo-ammono benzene sulfonic acid. This acid amide reacts with nitric acid to form a derivative known as benzene sulfonnitramide, CIHESOINHYf HONOS--+ GHSOINH-NO. + H.0. This latter substance because of the possession of a replaceable hydrogen atom is still acidic. Such compounds are theoretically impossible of realization among the aquo acids, for obviously the substitution of a second negative group in a molecule of water results not in the formation of an acid but of an acid anhydride. As far as one-half of the molecule, CsH5SOzNH-, is concerned, benzene sulfonnitramide is a mixed aqua-ammono i t is a sulfonic acid; and, as far as the other half is concerned, -NH-NO,, mixed aqua-ammono nitric acid. Because the acidifying power of two electronegative groups is directed to one hydrogen atom, benzene sulfonnitramide is a very strong acid. Numerous salts of this and other sulfannitramides have been prepared and found to be stable in water solution." Other typical representatives of this class of compounds are nitro urea, NH9CO-NHN02, nitromanidine, NHnC(NH)NHNOa,acetyl urea. CHsCONH CO-NH-CONH,, barbituric acid, CH
