Abstract: Carboxylic esters obtained by reacting olefinically unsaturated compounds with carbon monoxide and alcohols and containing aldehydes, acetals and/or unsaturated compounds are purified by(a) treating the carboxylic ester which contains an aldehyde, acetal or unsaturated compound in a first stage at from 20.degree. to 200.degree. C. with a strongly acidic agent and(b) hydrogenating the mixture thus treated in a second stage at from 50.degree. to 200.degree. C. under a pressure of from 1 to 50 bar in the presence of one or more metals of subgroup VIII of the periodic table and(c) removing low and high boilers from the hydrogenated mixture obtained in stage b by distillation and obtaining a pure carboxylic ester.

Abstract: Pyridine or methylpyridines or mixtures thereof are recovered from methyl butanedicarboxylate containing reaction mixtures obtained by reaction of methyl pentenoate with carbon monoxide and methanol in the presence of pyridine, methylpyridines or mixtures thereof and also cobalt catalysts at elevated temperatures and under superatmospheric pressure and subsequent treatment with molecular oxygen containing gases in aqueous acetic acid by(a) separating the reaction mixture on the one hand into an aqueous phase containing cobalt acetate, pyridine, methylpyridines or mixtures thereof, acetic acid and methanol and on the other an organic phase containing methyl butanedicarboxylate, by-products, unconverted methyl pentenoate, acetic acid and also pyridine, methylpyridines or mixtures thereof,(b) extracting the organic phase obtained in step (a) with aqueous acetic acid to obtain an aqueous extract containing pyridine or methylpyridines or mixtures thereof as well as acetic acid,(c) combining the aqueous extract obt

Abstract: 4-Pentenoates are prepared by isomerization by a process in which isomeric pentenoates are treated with a zeolite of the pentasil type at from 50.degree. to 300.degree. C., and the 4-pentenoate is distilled off from the reaction mixture.

Abstract: 4-Pentenoates are prepared by isomerization by a process in which isomeric pentenoates are treated at elevated temperatures in the presence of a zeolite containing metals of group eight of the Periodic Table and the 4-pentenoate is distilled off from the reaction mixture, and the zeolite contains iron, cobalt and/or nickel.

Abstract: Aliphatic dinitriles are prepared by reacting aliphatic dicarboxylic acids with ammonia in excess at from 200.degree. to 500.degree. C. in the presence of zeolites as catalysts.