METHOD OF PRODUCING METHACRYLIC ACID Russian patent published in 2016 - IPC C07C51/09 C07C57/04 C07C67/20 C07C231/06 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing methacrylic acid, which includes following steps: a) providing acetone cyanohydrin, b) conversion of acetone cyanohydrin to methacrylamide, c) esterification of methacrylamide in presence of alkanols to esters of methacrylic acid, and d) hydrolysis of esters of methacrylic acid to methacrylic acid using heterogeneous catalysts, wherein a stream of initial substances containing an ester of methacrylic acid from esterification step c) and water is fed to hydrolysis step d); re-circulated stream including first re-circulated flow from bottom of vacuum rectification column is fed to hydrolysis step d) for separation of low-boiling products and second re-circulated flow from upper part of rectification column for separation of alkanol; and weight or volume ratio of recirculating flow to flow of starting material ranges from 5 to 50.

EFFECT: method leads to formation of negligible amounts of spent acid and provides low power consumption.

9 cl, 2 ex, 1 dwg, 1 tbl