Verfahren zur Herstellung von Methacrylsäure

摘要

Disclosed herein is a process for producing methacrylic acid which comprises: (I) a step of producing acetonecyanohydrin from prussic acid and acetone; (II) a step of hydrating acetonecyanohydrin obtained in the preceding step (I) to form alpha -hydroxyisobutyric acid amide; (III) a step of reacting alpha -hydroxyisobutyric acid amide obtained in the preceding step (II) with methyl formate or methanol and carbon monoxide to form methyl alpha -hydroxyisobutyrate and formamide; (IV) a step of hydrolyzing methyl alpha -hydroxyisobutyrate obtained in the preceding step (III) to form alpha -hydroxyisobutyric acid; (V) a step of dehydrating alpha -hydroxyisobutyric acid obtained in the preceding step (IV) to form methacrylic acid; and (VI) a step of dehydrating formamide separated from the products obtained in the above step (III) to form prussic acid and of recycling the prussic acid to reuse as a starting material. The process is capable of producing methacrylic acid from easily available starting materials with a high yield and selectivity without forming undesirable by-product or waste material such as ammonium sulfate, etc.