VERFAHREN ZUR REINIGUNG VON ROHEN, HOCHSIEDENDEN CARBONSAEUREESTERN

摘要

The carboxylic esters to be purified are in particular esters of aromatic dicarboxylic acids with aromatic alcohols of 3-13 carbon atoms, which are obtained by esterifying using sulphuric acid as a catalyst, neutralising with alkali and driving off the excess alcohol with water vapour. The crude ester, heated to 140-160 DEG C, is admixed with 10-20% by weight of deionised water, so that the temperature falls to 90-100 DEG C. The crude ester is then treated with the aqueous alkali formed in order that electroconductive impurities or concomitants may be removed. The water which has been introduced is then removed from the two-phase mixture by renewed heating and vacuum distillation. The neutral ester left behind is filtered to remove the suspended concomitants. The process is simple and economical to carry out with a relatively short treatment time, and produces purified esters which are suitable for use as dielectrically high-grade plasticisers for plastics.