PREPARATION OF 5-METHYLBUTYROLACTONE

摘要

5-Methylbutyrolactone is prepared by a process in which a pentenoic ester of the formula I X-CO2R (I), where X is CH2=CH-CH2-CH2-, CH3-CH=CH-CH2- or CH3-CH2-CH=CH- and R is alkyl, cycloalkyl, aralkyl or aryl, or a mixture of these esters is reacted with water at from 50 DEG to 350 DEG C. in the presence or absence of a diluent a) over a zeolite and/or phosphate catalyst or b) in the presence of from 0.01 to 0.25 mole of a sulfonic acid, a Lewis acid and/or a non-oxidizing mineral acid per mole of pentenoic ester or over from 0.1 to 40% by weight, based on the pentenoic ester, of a strongly acidic ion exchanger as a catalyst in a first stage, or the pentenoic ester of the formula I, where X and R have the stated meanings, is hydrolyzed in a first stage with the aid of a strongly acidic ion exchanger as a catalyst to give the pentenoic acid of the formula I, where R is hydrogen, and the resulting pentenoic acid is subjected to cyclization in a second stage in the presence of from 0.005 to 0.1 mole of a sulfonic acid, a Lewis acid or a non-oxidizing mineral acid per mole of pentenoic acid or over from 0.1 to 20% by weight, based on the pentenoic acid, of a strongly acidic ion exchanger at from 50 DEG to 350 DEG C.