Lithium azide, decomposition

The crystalline diazonium salt will detonate at the touch of a spatula. An ethereal solution exploded violently after 1 h at —78°C, presumably owing to separation of the solid salt [1]. Many explosions were experienced in researches that showed that tetrazolylpenta-zoles were transient intermediates in reaction of the diazonium salt with lithium azide. There was then decomposition to tetrazolyl azides, themselves very explosive [2],... 

Although the rates of decomposition of different preparations of lithium azide differed markedly [34], reproducible behaviour was observed for salt which had been crushed and pelleted. Such pretreatment was believed to produce a uniform concentration of defects within the reactant assemblages. The sigmoid nr-time curves fitted the Avrami-Erofeev equation with = 3 between 0.02 < or < 0.58 and the contracting volume expression across the wider interval 0.05 < a< 0.95, the value of was 119 kJ mol". Reaction involved the three-dimensional growth of a constant number of nuclei and it was suggested that acceleration of rate following preirradiation resulted from an increase in the number of such nuclei. 

The decomposition of diazotates may also be induced by Lewis acids. Solution of (152) in hexamethylphosphoric triamide are slowly decomposed by excess lithium azide or lithium chloride with the formation of inverted 2-octyl azide and chloride, respectively, along with retained 2-octanol1491. Diazotates are readily decomposed by acylation. Although the intermediate diazoesters (125) should be identical with those generated by thermolysis of nitrosoamides, differences in stereochemistry and product distribution were noticed which may be due to the heterogeneity of the diazotate system149-15 D... 

Irradiation increased the rate of tliermal decomposition of lead azide, but the effect was not as pronounced as with lithium azide, for which the induction period was reduced to about one half and the rate increased considerably. Cadmium azide produced pressure-time curves similar to lead azide. Irradiated silver azide was unaffected, but the experiment was conducted at 315°C, which caused the silver azide to be molten. 

Further and important support for the hypothesis of alkenediazonium ions in the decomposition of nitroso oxazolidinones is provided by investigations by Kirmse et al. (1979) with the N-labeled nitroso compounds 5,5-dimethyl-3-nitroso-[3- N]-l,3-oxazolidin-2-one (2.259, R = H R" = R " = CH3) and 5,5-pentamethyl-ene-3-nitroso-[3-i N]-l,3-oxazolidin-2-one (2.259, R = H, R"-R "= -[CH2]5-). The authors determined the N content of products of decompositions conducted in the presence of lithium azide. The results are consistent with A-coupling of the intermediate with azide ions (for coupling of arenediazonium ions with azide ions see Zollinger, 1994, Sect. 6.4). 

This formation of spontaneously ignitible strontium and barium has been reported by Tiede, He also mentions the decomposition of calcium and lithium azide under the same conditions, but remarks only that lithium azide is rather explosive on heating. 

A novel method for preparing amino heterocycles is illustrated by the preparation of 2-amino-5-methylthiophene (159). In this approach vinyl azides act as NH2 equivalents in reaction with aromatic or heteroaromatic lithium derivatives (82TL699). A further variant for the preparation of amino heterocycles is by azide reduction the latter compounds are obtained by reaction of lithio derivatives with p- toluenesulfonyl azide and decomposition of the resulting lithium salt with tetrasodium pyrophosphate (Scheme 66) (82JOC3177). 

Lithium aluminium hydride reduction of 235 followed by mesylation afforded 236. The latter was oxidized with osmium tetroxide and sodium metaperiodate to yield the cyclobutanone 237. Treatment of 237 with acid afforded in 48% yield the ketoacid (238), which was esterified with diazomethane to 239. The latter was converted to the ketal 240 by treatment with ethylene glycol and /7-toluenesulfonic acid. Compound 240 was reduced with lithium aluminium hydride to the alcohol 241. This alcohol had been synthesized previously by Nagata and co-workers (164) by an entirely different route. The azide 242 was prepared in 80% yield by mesylation of 241 and treatment of the product with sodium azide. Lithium aluminium hydride reduction of 242 gave the primary amine, which was converted to the urethane 243 by treatment with ethyl chloroformate. The ketal group of 243 was removed by acidic hydrolysis and the resulting ketone was nitro-sated with N204 and sodium acetate. Decomposition of the nitrosourethane with sodium ethoxide in refluxing ethanol afforded the ketone 244 in 65% yield. The latter had been also synthesized previously by Japanese chemists (165). The ketone 244 was converted to the ketal 246 and the latter to 247... 

Under the appropriate conditions it undergoes hazardous reactions with Al, tert-butyl azido formate, 2,4-hexadiyn-l,6-diol, isopropyl alcohol, K, Na, sodium azide, hexafluoroisopropylideneamino lithium, lithium. When heated to decomposition or on contact with water or steam it will react to produce toxic and corrosive fumes of CO and Cr. Caution-. Arrangements should be made for monitoring its use. 

Small amounts of Na, K, Rb and Cs can be obtained by thermal decomposition of their azides (equation 10.2) an application of NaN3 is in car airbags (see equation 14.4). Lithium cannot be obtained from an analogous reaction because the products recombine, yielding the nitride, Li3N (see equation 10.6). 

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