FIELD: organic chemistry, chemical technology. SUBSTANCE: invention describes a method of synthesis of phenylpropionic acid taken from 2-(4-isobutylphenyl)propionic or 2-(2-fluoro-4-biphenylyl)-propionic acids or their salts, for example, methylbenzyl-amine, lysine or sodium salts that are enriched with the required enantiomer. Method involves the separation stage that is carried out by treatment with the corresponding enantiomer of racemic acid α-methylbenzylamine in solvent at heating to form the corresponding phenylpropionic acid salt enriched with the required enantiomer. Obtained salt is separated and then converted to phenylpropionic acid or one of the above indicated salts enriched with the required enantiomer followed by recrystallization stage. At the stage of separation (a) a mixture of toluene and methanol is used as a solvent and this stage is carried out at molar ratio of racemic phenylpropionic acid to α-methylbenzylamine from :0,25 to 1: 1. Then the stage of recrystallization (b) is carried out where the end enriched salt is recrystallized from a mixture methanol-toluene to obtain phenylpropionic α-methyl-benzylamine salt which enriched with the required enantiomer additionally. Then the optional release stage (c) is carried out where phenylpropionic acid enriched additionally with the required enantiomer is isolated from recrystallized salt; and (d) optional stage of salt preparing where phenylpropionic acid solid salt enriched additionally with the required enantiomer is isolated being solid salt enriched more with the required enantiomer. EFFECT: simplified process of synthesis. 24 cl, 2 tbl, 10 ex
