METHOD TO REDUCE CARBOXYBENZALDEHYDE ISOMERS IN TEREPHTHALIC ACID OR ISOPHTHALIC ACID

摘要

A method for reducing carboxybenzaldehyde isomers in crude terephthalic and/ or isophthalic acids is described. Crude TPA or IPA is dissolved in N-methyl pyrrolidone and is subsequently contacted with an oxidant, such as substantially anhydrous hydrogen peroxide, to convert the carboxybenzaldehyd e isomer (4-CBA or 3-CBA) to TPA or IPA under moderate temperature and pressur e conditions.