Use of beta-C-13 labelled coniferyl alcohol to detect "end-wise" polymerization in the formation of DHPs

The possibility that preformed dehydrogenation polymer (DHP) could function as a template to induce a structural pattern in DHP more closely resemblin g that of natural softwood lignin was investigated by oxidizing beta C-13-l abelled coniferyl alcohol in a medium containing preformed unlabelled polym eric DHP. The experiments were performed at pH 4 and pH 6.5. 1D and 2D NMR were used to estimate the distribution of structural units. No such templat e effect was found in a comparison of unlabelled with uniformly labelled DH P. Indeed, the effect of pH on the coupling pattern of coniferyl alcohol wa s geater than the effect of the preformed DHP.