FIELD: chemistry.
SUBSTANCE: invention relates to a method for synthesis of 2-oxo-methylthiobutanoic acid of formula (I) and its salts, 
, where R is a carboxyl group and its salts. The method is distinguished by that it comprises the following stages: catalytic and selective oxidation of but-3-ene-1,2-diol (II) to obtain 2-oxo-but-3-enoic acid (III) in accordance with the following reaction scheme (i): 
and selective condensation of methyl mercaptan with 2-oxo-but-3-enoic acid (III) in accordance with the following reaction scheme (ii): 
. The invention also relates to a method for synthesis of formula (I) compound, to a method for synthesis of 2-oxo-but-3-enoic acid (III), to a food additive, to a food ration, to a method of administering biologically active methionine to cattle, as well as to use of 2-oxo-4-methylthiobutanoic acid of formula (I).
EFFECT: obtaining 2-oxo-4-methylthiobutanoic acid, its salts and its use in feeding animals.
24 cl, 8 ex, 4 tbl, 1 dwg
