Process for the preparation of substituted hydroxyhydrocinnamate esters by removal of tin catalysts

An improved process for the preparation of a compound of formula (I)

• wherein R is an alkyl of 1 to 4 carbon atoms, n is 0 to 2, m is 1 to 4;
• and
• when m is 1, A is a straight or branched chain alkyl of 4 to 18 carbon atoms;
• when m is 2, A is a straight or branched chain alkylene of 2 to 12 carbon atoms, or said alkylene interrupted by one to five O or S atoms, or A is 2,2-bis(4-ethyleneoxyphenyl) propane;
• when m is 3, A is a straight or branched chain alkanetriyl of 3 to 6 carbon atoms;
• and
• when m is 4, A is pentaerthyrityl,
• by transesterifying the corresponding lower alkyl ester with an alcohol of the formula (II)
• A-(OH)m (II)
• in the presence of a tin catalyst;
• wherein the improvement comprises reacting the tin catalyzed transesterification reaction mass with a carboxylic acid or hydrate thereof neat, in the absence of an aqueous medium, until the tin catalyst forms an insoluble derivative, and separating the insoluble derivative from the reaction mass by filtration.