METHOD OF PREPARING METHACRYLIC ACID ESTERS Russian patent published in 1999 - IPC

FIELD: chemical industry. SUBSTANCE: method comprises hydrolysis of acetonecyanohydrine to with sulfuric acid prepare hydrolysis mixture and esterification and separation of esterified mixture. Hydrolysis is carried out in such conditions under which total number of moles of 2-methacrylamide, α-sulfateisobutyr amide, α- hydroxyisobutyr amide and methacrylic acid present in the resulting hydrolysis mixture proves to be optimal, and the resulting hydrolysis mixture is then esterified with C₁-C₁₂ alkyl alcohols to prepare esterified mixture which comprises C₁-C₁₂ alkyl methacrylate, C₁-C₁₂ alkyl-α- hydroxyisobutyrate, C₁-C₁₂-alkyl-β-C₁-C₁₂-alkoxyisobutyrate and C₁-C₁₂ alkyl-α-C₁-C₁₂ alkoxyisobutyrate. Separation of esterified mixture gives aqueous fraction, first organic fraction comprising C₁-C₁₂ alkylmethacrylate, and second organic fraction comprising C₁-C₁₂ alkyl -α-hydroxyisobutyrate, C₁-C₁₂ alkyl-β-C₁-C₁₂ alkoxyisobutyrate and C₁-C₁₂ alkyl-α-C₁-C₁₂- alkoxyisobutyrate, second organic phase components are then dehydrated to prepare mixture comprising C₁-C₁₂ alkylmethacrylate, methacrylic acid, C₁-C₁₂ alkyl alcohol and water, mixture is recycled, and recycled mixture is combined either with hydrolysis mixture or with esterified mixture. EFFECT: increased yield of α,β- unsaturated carboxylic acid esters and smaller amount of the resulting reaction by-products and semiproducts recycled to process. 10 cl, 2 ex, 1 tbl