To provide an industrially advantageous method for obtaining an aqueous high concentration α-hydroxy acid ammonium salt solution, getting less effect by the decrease of reaction rate caused by the increase of product concentration and capable of suppressing the using amount of an expensive biocatalyst as minimum.
This method for producing the α-hydroxyacid by hydrolyzing an α-hydroxynitrile compound expressed by formula, RCH(OH)CN, with the biocatalyst in an aqueous medium to convert to an α-hydroxyacid ammonium salt expressed by formula, RCH(OH)COO-NH4+, by using at least 2 steps of reaction vessels comprises the steps of: transporting the reaction liquid in each of the reaction vessels to the next step reaction vessel one by one; and adding the α-hydroxynitrile compound to the reaction vessel to which the reaction liquid is transported so as to increase the accumulated concentration of the α-hydroxyacid ammonium salt in the reaction vessel in each of the steps one by one as step wise.
HAYAKAWA KOICHI
MIZUI YOSHINORI
YOKOYAMA MASAHIRO
Seiji Ozawa
Haruka Oka
Large High Toshiko
High Kazuya Tsu