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The alkylation of 5 (β dimethylaminoethyl)tetrazole (1) with dimethyl sulfate afforded 5 (β dimethylaminoethyl) 1 methyltetrazole (2) and 5 (β dimethylaminoethyl) 2 methyltetr azole (3). The exhaustive alkylation of compounds 2 and 3 at the terminal dimethylamino group gave 1 methyl (4) and 2 methyl 5 (β trimethylammonioethyl)tetrazole (5) methyl sul fates. The proton elimination from the α methylene (with respect to the tetrazole cycle) groups of the quaternary ammonium cations of salts 4 and 5 by the action of a base leads to the corresponding zwitterions 4 ± and 5 ± , which in the rate determining step undergo the cleavage of the nitrogen-carbon bond with the formation of 1 methyl 5 vinyl (6) and 2 methyl 5 vinyltetrazole (7). The true constant of the transformation of zwitterion 4 ± into tetrazole 6 is 21 times higher than that for the transformation of zwitterion 5 ± into tetrazole 7.Key words: 1 methyl 5 vinyltetrazole, 2 methyl 5 vinyltetrazole, kinetics of formation, deamination mechanism.Isomeric N alkyl 5 vinyltetrazoles are initial mono mers in the synthesis of the corresponding poly(vinyl tetrazoles), which are promising high energy polymers with a series of unique properties. 1 Beginning from the 1960s chemists are searching for efficient methods of syn thesis of N alkyl 5 vinyltetrazoles. 2 This search is imped ed by numerous quantitative studies of key chemical pro cesses resulting in 5 vinyltetrazole derivatives. The results on studying the kinetics of alkylation of NH unsubstituted 5 vinyltetrazole with methyl iodide in an acetonitrile me dium in the presence of triethylamine have recently 3 been published. The hypothetical mechanism was formulated 3 and the boundaries for changing the reaction conditions, which allow one to control the rate and selectivity of alky lation in certain limits, were determined. However, since the initial substrate is NH unsubstituted 5 vinyltetrazole is a hardly accessible compound yet, the patented method for the preparation of N alkyl 5 vinyltetrazoles based on the synthesis and subsequent alkylation of 5 (β dimethyl aminoethyl)tetrazole with dimethyl sulfate in an aqueous medium in the presence of alkaline metal hydroxide seems more promising. 4,5 The variants of this method described in the cited patents are almost identical and only differ by the nature of the base used: NaOH (see Ref. 4) and KOH (see Ref. 5), respectively. Let us consider the hypothetical sequence of the synthesis of isomeric N methyl 5 vinyltetr azoles postulated in the patents 4,5 (Scheme 1).Isomeric vinyltetrazoles 6 and 7 are formed due to the deamination of intermediate quaternary ammonium salts Scheme 1

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