Hydrogen azide solutions

The free acid, l,2,3,4-thiatriazole-5-thiol, may be prepared from hydrogen azide and carbon disulfide, but the simplest way to obtain the acid is to treat a chilled solution of the sodium salt with concen-... 

A different reaction takes place between an ethereal solution of the disulfide and hydrogen azide this reaction proceeds according to Eq. (15). Probably the principal step of this reaction is the spontaneous decomposition of the disulfide into nitrogen, sulfur, and... 

An ethereal solution of some 100 g of the crude nitrile was allowed to spontaneously evaporate and crystallise. The crystalline slurry so produced exploded violently without warning. Previously such material had been found not to be shock-sensitive to hammer blows, but dry recrystallised material was very shock-sensitive. Traces of free hydrogen azide could have been present, and a metal spatula had been used to stir the slurry, so metal azides could have been formed. See Other CYANO COMPOUNDS, ORGANIC AZIDES... 

A solution, prepared by mixing saturated solutions of cadmium sulfate and sodium azide in a 10 ml glass tube, exploded violently several horns after preparation [1], The dry solid is extremely hazardous, exploding on heating or light friction. A violent explosion occurred with cadmium rods in contact with aqueous hydrogen azide [2], A DTA study showed a lesser thermal stability than lead azide [3], It is strongly endothermic (AH°f (s) +451 kJ/mol, 2.32 kJ/g). 

Ross, F. F., Water Waste Treatment, 1964, 9, 528 private comm., 1966 One of the reagents required for the determination of dissolved oxygen in polluted water is a solution of sodium azide in 50% sulfuric acid. It is important that the diluted acid should be quite cold before adding the azide, since hydrogen azide boils at 36°C and is explosive in the condensed liquid state. 

Ray, P. C. et al., J. Chem. Soc., 1911, 99, 1470 1912, 101, 141, 216 Ammonium and substituted-ammonium nitrite salts exhibit a range of instability, and reaction mixtures which may be expected to yield these products should be handled with care. Ammonium nitrite will decompose explosively either as the solid, or in cone, aqueous solution when heated to 60-70°C. Presence of traces of acid lowers the decomposition temperature markedly. Hydroxylammo-nium nitrite appears to be so unstable that it decomposes immediately in solution. Hydrazinium(l+) nitrite is a solid which explodes violently on percussion, or less vigorously if heated rapidly, and hydrogen azide may be a product of decomposition [1], Mono- and di-alkylammonium nitrites decompose at temperatures below 60-70°C, but usually without violence [2], Individual entries are ... 

The azides of the 1,1 -diphenyl series were prepared by adding hydrogen azide to the appropriate olefin. The reaction is catalyzed by trichloroacetic acid and carried out in benzene solution [56],... 

The reaction is monomolecular. The half-life at 330°C is 12 min. In a dilute aqueous solution hydrazoic acid is stable and not liable to decompose even on long boiling (Curtius [46]). However, a 17% aqueous solution of hydrogen azide can probably detonate [47]. 

Incubate slides in sodium azide/hydrogen peroxide solution for 20 mm at room temperature (see Note 6). 

Sodium azide/hydrogen peroxide solution blocks endogenous peroxidase enzyme activity This is important m cervical smears where large numbers of neutrophil polymorphs and red blood cells are present. Although often not essential when analyzing cultured cells or biopsies, incubation m this solution is equally effective with these sample types. 

Aqueous solutions of hydrogen azide are readily obtained by treatment of sodium azide f with sulfuric acid. Since pure hydrogen azide is extremely explosive, and since its vapors produce most unpleasant physiological effects, it is advisable to use care in its preparation. Especially is the treatment of dry sodium azide, or of a cold solution, with sulfuric acid to be avoided, since this results in the formation of pure hydrogen azide (b. 37°C.) which may condense to the anhydrous liquid or to a highly concentrated aqueous solution, both of which are extremely explosive. 

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. HYDRAZOIC ACID (AQUEOUS SOLUTION OF HYDROGEN AZIDE)... 

Since the distribution ratio of hydrogen azide between the two solvents ether and water is approximately 7 1, ethereal solutions may be prepared by extraction of aqueous solutions with ether. However, the procedure used by Frost, Cothran, and Browne6 is preferable. 

The addition of sodium hydroxide is purely precautionary. It avoids the formation of a high concentration of hydrogen azide in a cold solution. 

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. 

See also Hydrogen bromide) Hydrogen azide, 77 ethereal solution, 77, 78 Hydrogen bromide, 39, 114, 149, 151, 152... 

Nitrites give a similar reaction and may be removed most simply with the aid of sulphamic acid (see reaction 3). Another, but more expensive, procedure involves the addition of sodium azide to the acid solution the solution is allowed to stand for a short time and then boiled in order to complete the reaction and to expel the readily volatile hydrogen azide ... 

The reaction of equimolar quantities of hydrazoic acid with an acid or ketone affords a convenient method for preparing certain amines. The reaction is carried out by treating the organic compound in an inert solvent in the presence of sulfuric acid with gaseous hydrogen azide, hydrazoic acid in solution, or sodium azide directly. An excess of hydrazoic acid should be avoided in the reaction of ketones, for then tetrazoles are formed. It should be recalled that hydrazoic acid is toxic and explosive. A discussion of the method including scope and limitations, experimental conditions and procedures, and compounds prepared thereby has been presented. ... 

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