METHOD FOR PRODUCING 2-(4-N, N-DIALKYLAMINO-2-HYDROXYBENZOYL)BENZOATES

摘要

The invention relates to a method for producing 2-(4-N,N-dialkylamino-2-hydroxybenzoyl)benzoates of formula (I), in which the substituents R<1> to R<3>, independently of one another, are defined as cited in the description. Said substances are produced as follows: I. 3-N,N-dialkylaminophenol of formula (II) is reacted with phthalic anhydride of formula (III) to obtain 2-(4-N,N-dialkylamino-2-hydroxybenzoyl) benzoic acid of formula (IV) and II. said 2-(4-N,N-dialkylamino-2-hydroxybenzoyl) benzoic acid of formula (IV) that has been formed in stage I. is esterified by means of a C1-C12 alcohol or a cyclic C3-C10 alcohol in the presence of an acidic catalyst to obtain 2-(4-N,N-dialkylamino-2-hydroxybenzoyl)benzoate of formula (I). The method is characterised in that the ester of formula (I) that has been formed is purified in an additional stage III by treatment with an adsorbent and/or by distillation.