Potassium hydrazoate

Potassium hydrazoate, KN3.—On concentrating a solution of hydra-zoic acid neutralized with potassium hydroxide, the hydrazoate separates in doubly refracting crystals. It is not very explosive, but melts and decomposes above 350° C. The aqueous solution has a slight alkaline reaction, the solubility at 17° C. being 49-6 grams per 100 grams of water.3... 

Hydrazoic acid reacts with potassium permanganate. They mutually reduce each other to evolve a mixture of nitrogen and oxygen. Nitrous acid oxidizes hydrazoic acid with the evolution of nitrogen. 

Potassium azide was claimed to be first prepd in 1898 by Dennis Benedict (Ref lb) and in the same year by Curtius Rissom (Ref 2), both by methods involving evapn of a soln of KOH neutralized with a slight excess of hydrazoic acid, HN3. This same method of prepn was described in 1894 by Dennis (Ref la). Browne Houlehan (Ref 3) obtd KNS by reactg metallic K with NH4N3 in liq NHj. Other methods of prepn are described by Hoth Pyl (Ref 16), Moldenhauer MiSttig (Ref 17), Wattenburg(Ref 17a), Franklin (Ref 19), Audrieth et al (Refs 21,... 

Potassium bisulfite reduces fluoroalkylnitroso compounds to the oximes, with the exception that the parent mtrosotnfluoromethane is converted to the corresponding hydroxylamine [90] (equation 72). ArylfluoroaJkylazo compounds are reduced to the hydrazo stage or the fluoroamine by zinc-add, depending on conditions [91] (equation 73) Of the various reagents tested tor selective reduction of ji-fluoroalkyl azides to P-fluoroalkylamines, triphenylphosphine was the best [92] (equation 74). 

AZIDES. The salts of hydrazoic acid are termed azides. Metallic azides can be prepared from barium azide and the metal sulfate, or from potassium azide and the metal perchlorate. 

Angeli35 obtained a white precipitate of insoluble silver azide by mixing saturated solutions of silver nitrite and hydrazine sulfate and allowing to stand in the cold for a short time. Dennstedt and Gohlich 36 later procured free hydrazoic acid by the interaction of hydrazine sulfate and potassium nitrite in aqueous solution. 

T. Curtius and A. Darapsky prepared a basic salt, lanthanum hydroxyazide, La(0H)(N3)2l H20, by boiling a soln. of lanthanum nitrate and sodium azide. The white, slimy mass of basic lanthanum azide is obtained by evaporating the mixed soln. in vacuo, or by treatment of the soln. with a mixture of alcohol and ether. They also made rose-coloured didymium hydroxyazide, Dy(OH)(N3)2, by evaporating a soln. of didymium carbonate in hydrazoic acid. Freshly precipitated yttrium hydroxide dissolves in hydrazoic acid, forming a soluble yttrium hydroxyazide boiling a soln. of yttrium sulphate and sodium azide gives a precipitate of yttrium hydroxide. L. M. Dennis found that zirconium hydroxide is precipitated when a soln. of zirconium salt is treated with potassium azide. 

In addition to the method outlined under procedure A, hydrazoic acid may be prepared by the action of oxalic1 or fluosilicic acids2 upon solutions of sodium azide or by the treatment of barium azide solutions with dilute sulfuric acid. A method involving the action of perchloric acid upon potassium azide has also been proposed. However, subsequent distillation of the filtrate, after removal of the precipitated potassium perchlorate, is necessary to prepare pure hydrazoic acid. Pure hydrazoic acid has also been obtained by the oxidation of hydrazine in acid solution by hydrogen peroxide.3-"... 

A 3 per cent solution of hydrazoic acid (synthesis 26A) is neutralized with an aqueous solution of pure potassium hydroxide. The resulting solution of potassium azide is concentrated on the steam bath to incipient crystallization. The solution is then made slightly acid with hydrazoic acid to replace the hydrogen azide lost by hydrolysis. A volume of ethyl alcohol twice that of the solution is added, and the solution is cooled in an ice bath. Since the solubility in alcohol of the alkali and alkaline earth azides is very slight (see table below), precipitation in the form of a white microcrystalline salt takes place readily. From 90 to 95 per cent recovery of the theoretical quantity of potassium azide can be effected. The precipitated azide is filtered on a Buchner funnel and washed with cold absolute alcohol and then with ether. Any traces of adhering solvent may be removed in a vacuum desiccator. In a typical run, 300 ml. of a solution of hydrazoic acid containing 8.5 g. of HN3 was neutralized with potassium hydroxide, and the isolation of potassium azide effected as indicated above. Yield 14.7 g. (91.5 per cent) KN3. 

Related reactions of the substituted alkenes 176 and 178 with basic nucleophiles such as ammonia occur at C-3 and C-2, respectively, to give the thermodynamically favored gluco adducts 177200 and 179.201 Alternatively, the nitroalkene 178, under neutral or weakly acid conditions, adds nucleophiles such as hydrazoic acid, hydrogen cyanide-potassium cyanide, or purine bases at C-2 to give the a-manno products.201... 

N3C2H202(NH2) Urazine (4-amino-urazole), 4 29 salts, 4 31 NsCs Cesium azide, 1 79 NSH Hydrazoic acid, 1 77, 78 Hydrogen azide, 1 77, 78 N3K Potassium azide, 1 79 2 139, 140... 

Thiatriazole-5-thiol is a fairly strong acid and its salts are readily obtained from the water-soluble alkali and alkaline earth azides with CS2 at 40 °C (equation 43) (64AHC(3)263). These should be handled with care. The potassium salt may explode violently when spread on a porous plate and the slightly soluble heavy-metal salts are very sensitive to shock even under water. An improved method for the preparation and storage of sodium thiatriazole-5-thiolate has been reported (74MI42800). l,2,3,4-Thiatriazole-5-thiol is prepared by addition of concentrated hydrochloric acid to a chilled solution of the sodium salt, obtained as a white or slightly yellow crystalline compound. The free acid can also be prepared from hydrazoic acid and carbon disulfide (equation 43) (64AHC(3)263). 

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