The invention belongs to the technical field of
impurity removal of fine chemicals, and particularly relates to a method for removing
impurity valeric acid in
valproic acid in a
sodium valproate synthesis process. The method for removing the
impurity valeric acid comprises the following steps: adding methylbenzene and water into decarboxylated
mother liquor, and carrying out suction
filtration; standing and layering the filtrate, and removing a lower-layer water phase; adjusting the pH gt by a
toluene layer; 10; standing for layering, keeping a water phase, adding methylbenzene, and adjusting the pH to be 1t; 2; adding
hydrochloric acid and
toluene into the residual water phase, standing for layering, reserving a
toluene layer, carrying out first alkali extraction operation, standing for layering until the residual
valeric acid in the toluene layer is lower than 0.1%, adding
hydrochloric acid and toluene into the residual water phase, layering, reserving the toluene layer, and carrying out second alkali extraction operation until the residual valeric acid is lower than 0.1%; mixing toluene
layers after two times of alkali extraction, then dropwise adding an alkali solution, adjusting the pH value, and treating to obtain a
sodium valproate crude product; according to the method for removing the impurity valeric acid in the
valproic acid in the
sodium valproate synthesis process provided by the invention, the content of the valeric acid in the sodium valproate crude product is low, and the purity of the prepared sodium valproate is high.