Hydrogen azide stabilization

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). 

Buell, McEwen, and Kleinberg have observed that weak acids such as hydrogen azide and acetic acid add readily across the double bond of vinylferrocene (XLI, M = Fe) (8). They have postulated that the mechanism of addition proceeds via intermediate formation of the a -ferrocenylcarbonium ion (X-LII, M = Fe), followed by conversion to the acetate (XLIII, M = Fe). Stabilization of carbonium ions of this type can result from overlap of filled metal orbitals with the vacant p -orbital of the carbonium ion. 

Organylazidosilanes (general formula RnSi(N3)4 n R = Me, Ph n = 3,2,1) are thermally stable derivatives of hydrogen azide. This is most likely due to an enhanced mesomeric stabilization by formation of a d —pn bond between N and Si atoms. 

N.B. A number of serious accidents have occurred due to spontaneous explosion of organic azides. Statements in the literature about the supposed stability of individual azides, particularly those of low molecular weight, should not be implicitly trusted (see, for example, Grundmann and Haldenwanger660). All operations with azides must be carried out with extreme care and with safety precautions similar to those used in work with peroxides, as described on page 306. Particular attention is directed also to the toxicity of hydrogen azide (hydrazoic acid). 

The 2,6-dimethylbenzyl ether is considerably more stable to hydrogenolysis than is the benzyl ether. It has a half-life of 15 h at 1 atm of hydrogen in the presence of Pd-C whereas the benzyl ether has a half-life of —45 min. This added stability allows hydrogenation of azides, nitro groups, and olefins in the presence of a di-methylbenzyl group. ... 

Esters of a-diazoalkylphosphonic acids (95) show considerable thermal stability but react with acids, dienophiles, and triphenylphosphine to give the expected products. With olefinic compounds in the presence of copper they give cyclopropane derivatives (96), but with no such compounds present vinylphosphonic esters are formed by 1,2-hydrogen shift, or, when this route is not available, products such as (97) or (98) are formed, resulting from insertion of a carbenoid intermediate into C—C or C—H bonds. The related phosphonyl (and phosphoryl) azides (99) add to electron-rich alkynes to give 1,2,3-triazoles, from which the phosphoryl group is readily removed by hydrolysis. 

Amino-5-nitro-1,2,3-triazole (ANTZ) (130), an explosive showing high thermal stability, has been synthesized via this route the reaction of sodium azide, acetaldehyde and 2,2-dinitroethyl acetate forming 4-methyl-5-nitro-1,2,3-triazole, which on conversion of the methyl group to an amino group yields ANTZ (130). Treatment of ANTZ (130) with hydrogen peroxide in sulfuric acid yields 4,5-dinitro-1,2,3-triazole (DNTZ) (131). 

Efforts towards stabilization of metaphosphonimidates with bulky substituents failed. Photolysis of 5 at low temperature did not allow us to stabilize or ]. Irradiation of y in benzene gave rise to dimers and polymers but also to the hydrogen abstraction product. Moreover we did not succeed at the present time in the preparation of the phosphorus azide 2 from 8 certainly because of steric hindrance. 

Hydroxylamine-O-sulfonic acid reacts with hydrazine to form a precipitate of triazanium hydrogensulfate (H2NNH2 NH2)+ HS04. Reaction of this solution with an appropriate barium salt in 0.1 M aqueous solution yielded solutions of the nitrate, perchlorate, chlorate, acetate, cyanide, bromide, and hydroxide salts. The stability of the salts decreases in the order hydrogen sulfate > nitrate > perchlorate > chlorate > acetate > azide > cyanide > bromide > hydroxide. The stabihty of the solutions decreases with decreasing H+ concentration, thus stronger acids form more stable salts. 

For instance, a dip-coating technique can be used to prepare GaN films from either [Ga(N3)3]o= or the base-stabilized species . A unique azide that contains no carbon or hydrogen is [Cl2GaN3]3. It can be used to form GaN under ultra high vacuum CVD conditions . A related derivative, monomeric Cl2GaN3-NMe3, has a higher vapor pressure and can be used to form pure GaN (1-2 atom % carbon and chlorine) more effectively ... 

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