FIELD: organic synthesis.
SUBSTANCE: method of preparing an azocarboxylic acid ester comprises synthesis an azoiminoether via reaction of azonitrile with alcohol and hydrochloric acid in aromatic solvent at HCl/azonitrile molar ratio 2-6 if alcohol is methanol and 3-6 if alcohol is ethanol or higher alcohol. Resulting azoiminoether hydrochloride is hydrolyzed by gradually adding water to reaction mixture and slowly pouring reaction mixture to water at 15 to 50оС. Mixture of liquid azocarboxylic acid esters is prepared by synthesizing azoiminoether hydrochlorides, hydrolyzing them with water, and recovering desired esters from organic phase. Invention provides mixture of azocarboxylic acid ester salts corresponding to formula II:
(II), where R1, R2, R3, and R4 represent С1-С4-alkyl groups; R and R' are independently selected from group including linear or branched aliphatic С1-С4-radicals. Invention provides liquid mixture of azocarboxylic acid esters corresponding to formula III: 
(III) wherein R1, R2, R3, R4, R, and R' have the same meanings as in formula II.
EFFECT: increased yields and purity of products.
23 cl, 4 tbl, 6 ex
