The incorporation of 3,4-dichloroaniline, a pesticide metabolite, into dehydrogenation polymers of coniferyl alcohol (DHPs)

A mechanism by which pesticide metabolites may become incorporated into plant lignins has been studied with the aid of 3,4-dichloroaniline (DCA) and lignin model compounds. DCA was found to react rapidly with a quinone methide representing an intermediate in lignin biosynthesis. The resulting benzyl-amine group was stable to mild acidolysis under simulated stomach conditions. Addition of DCA to dehydrogenative polymerizations of coniferyl alcohol yielded DHPs containing covalently bended DCA. NMR spectroscopy showed that the DCA had become bonded to the benzylic position in arylglycerol-beta-guaiacyl ether structures. The majority of these structures were phenolic. This observation and the fact that the DCA accumulates in the low molecular weight fraction of the DHP indicates that the DCA functions as a trap for quinone methides and stops the further growth of the polymer.