43—THE INTRODUCTION OF AMIDE AND ESTER CROSS-LINKS INTO WOOL

Abstract

An account is given of the examination of carbodiimides and ethyl chloroformate as cross-linking agents for wool. The level of cross-linking was estimated from the extent of swelling of the treated wool in formic acid. Carbodiimide treatments resulted in the condensation of amino and carboxyl side chains to give amide cross-links; ester cross-links were also formed by condensation of hydroxyl and carboxyl side chains, Hydroxylamine treatments, which cleaved the ester but not the amide cross-links, were used to estimate the relative abundance of the two types of cross-link. N-Hydroxysuccinimide strongly promoted the cross-linking of wool with carbodiimides, most of the extra cross-links introduced being esters. The treatment of wool with ethyl chloroformate introduced relatively few cross-links. The main reactions are believed, on the basis of indirect evidence, to be esterification of carboxyl side chains and conversion of amino side chains to urethanes.