A method of alkyl 1,2-dichlorovinyl ketones preparation from acyl halides and 1,2-dichloroethylene was developed. The configurational equilibrium and electronic structure of alkyl 1,2-dichlorovinyl ketones was investigated by IR, 1 H and 13 C NMR spectroscopy, by measuring dipole moments, and by quantum-chemical calculations using methods RHF and B3LYP in the basis 6-311++ G (d,p). Alkyl 1,2-dichlorovinyl ketones are stable in the Z,s-cis-configuration where the olefin proton is involved into an intramolecular hydrogen bond with the oxygen of the carbonyl group. Reaction of 1,2-dichlorovinyl ketones with alkylhydrazines afforded 1-alkyl-3-alkyl-4-chloropyrazoles. The reaction of alkyl 1,2-dichlorovinyl ketones with 1,1-dimethylhydrazine involved dehydrochlorination and afforded 1,1-dimethylhydrazinium hydrochloride and a mixture of compounds with uncertain structure. B +&O $ON&2&&O &+&O ,9 B 9, , B ,,,Under conditions used in the synthesis of dichloromethyl 1,2-dichlorovinyl ketone [3] but applying the commercially produced mixture of cis-and trans-1,2dichloroethenes methyl and propyl 1,2-dichlorovinyl ketones were obtained in the yield not exceeding 24%. Alk = Me (I, IV), Et (II, V), Pr (III, VI).

Ketones P 0200Synthesis, Structure, and Characteristics of 1,2-Dichlorovinyl Alkyl Ketones. -A method for the synthesis of alkyl 1,2-dichlorovinyl ketones (III) in high yields (75-90%) is developed. The spectral data indicate that the Z,s-cis structure is favored. Reaction of the mixtures with monoalkylhydrazines affords pyrazoles. However, the reaction with dialkylhydrazine affords the corresponding hydrazinium hydrochloride and a mixture of compounds with uncertain structure. -(BOZHENKOV, G. V.; LECKOVSKAYA, G. G.; LARINA, L. I.; USHAKOV, P. E.; DOLGUSHIN, G. V.; MIRSKOVA, A. N.; Russ.