PROCESS FOR PREPARING 3 PENTENOIC ACID ESTERS FROM 2-PENTENOIC ACID ESTERS

摘要

3-pentenoates are prepared from 2-pentenoates by a process in which (a) a 2-pentenoate of the formula I where R1 is alkyl of 1 to 12 carbon atoms, cycloalkyl of 5 to 8 carbon atoms, aralkyl of 7 to 10 carbon atoms or aryl of 6 to 10 carbon atoms, is reacted with a compound of the formula II R2-X-H II where R2 has the meanings given for R1 and X is an oxygen or sulfur atom, or with a compound of the formula III III where R3 is hydrogen or R3 and R4 are each alkyl of 1 to 12 carbon atoms, cycloakkyl of 5 to 8 carbon atoms, aralkyl of 7 to 10 carbon atoms or aryl of 6 to 10 carbon atoms, and R3 and R4 together with the nitrogen atom on which they are substituents may form a 5-membered to 7-membered ring which may additionally contain a nitrogen or oxygen atom as a hetero atom, at from 20 DEG to 300 DEG C., in the presence or absence of a basic catalyst, to give a compound of the formula IV IV where Y is -XR2 or in which X, R1, R2, R3 and R4 have the above meanings, and (b) the compound of the formula IV is cleaved in the liquid or gas phase in the presence of an acidic catalyst at from 150 DEG to 450 DEG C. to give a mixture of 3- and 2-pentenoates, and the 3-pentenoate is isolated.