PROCESS FOR THE PREPARATION OF 5-CARBOXYPHTHALIDE AND ITS USE FOR THE PRODUCTION OF CITALOPRAM

摘要

There is described a process for the preparation of 5-carboxyphthalide, which comprises adding terephthalic acid to fuming sulfuric acid containing at least 20% by weight of SO3, then adding formaldehyde to the mixture, heating the mixture at a temperature of 120-145 ~C and isolating 5-carboxyphthalide from the reaction mixture.