Abstract: The preparation of 3-arylacrylic acids and their derivatives I ##STR1## where Ar is aryl which can additionally have substituents which do not react with ketene and are stable under the conditions of the reaction described below, andR.sup.1 is hydrogen, an alkali metal, an alkaline earth metal, ammonium or C.sub.1 -C.sub.20 -alkyl,comprises a first stage in which a dialkyl acetal of an aromatic aldehyde of the formula II ##STR2## where R.sup.2 is C.sub.1 -C.sub.4 -alkyl, is reacted with ketene of the formula CH.sub.2 .dbd.C.dbd.O in the presence of catalytic amounts of a protic or Lewis acid to give a 3-arylpropionic acid derivative of the formula III ##STR3## and a second stage in which this intermediate III is reacted in the presence of acid or base and, in the case where R.sup.1 is C.sub.1 -C.sub.20 -alkyl, additionally with a C.sub.1 -C.sub.20 -alkanol to give the final product I.

Abstract: A process for completing the esterification of aliphatic carboxylic acids of 1 to 8 carbon atoms with aliphatic or cycloaliphatic alcohols of 3 to 10 carbon atoms at the boiling point of the alcohol in a column operated with bottom heating, the lower space of the column being free from fitments, the middle space being provided with a packing and the upper space being provided with a packing or other fitments, in which process the water of esterification is driven off at the top of the column by azeotropic distillation, the starting mixture is fed into the side of the column from 5 to 10 m above the liquid level, the ester formed is taken off as liquid from the column bottom, and the column is operated with flooding such that the liquid level is from 6 to 10 m, with the liquid mixture filling the lower column space, which is free from fitments, and the lower part of the packed layer above the said space.