ENZYME-MEDIATED COUPLING OF 3,4-DICHLOROANILINE AND FERULIC ACID - A MODEL FOR POLLUTANT BINDING TO HUMIC MATERIALS

To investigate the incorporation of chloroanilines into humic substanc es, the reaction of ferulic acid with three different chloroanilines i n the presence of a laccase of the fungus Rhizoctonia praticola was in vestigated. Under the reaction conditions used, chloroanilines alone w ere not transformed by the laccase, but in the presence of ferulic aci d they formed cross-coupling products. The reactivity of anilines decr eased with increasing chlorine substitution on the ring. Two dimeric c ompounds were isolated from the reaction assay of ferulic acid alone. The dimers were found to have phenylcoumaran and lactone structures. A fter reacting ferulic acid with 3,4-dichloroaniline, two trimers were isolated and identified, providing insight into the reaction mechanism ; the two hybrid trimers contained one aniline and two ferulic acid mo lecules. The formation of the hybrid trimers can be best rationalized by the nucleophilic addition of 3,4-dichloroaniline to quinone methide intermediates produced from the radical coupling of ferulic acid.