On the use of watersoluble carbodiimides for binding carboxylic compounds to aminated dextrans

Summary To prepare dextran-linked benzene polycarboxylic acids which are stable in-vivo, the acids were allowed to react with aminated dextrans in water, in the presence of a water-soluble carbodiimide. Under these conditions, ester linkages are formed preferentially to amide ones, probably because of the formation of intramolecular cyclic anhydrides promoted by the carbodiimide. Thus, with benzoic acid, esterification also took place, but to a much lesser extent.Abbreviations EDCI 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide - Dex OH dextran - BHC benzene hexacarboxylic acid - BTC 1,2,4,5-benzene tetracarboxylic acid - BTCA 1,2,4,5-benzene tetracarboxylic anhydride - DSS 3-(trimethylsilyl)-1-propanesulfonic acid, sodium salt