Fundamental study of relative delignification efficiencies .2. Combinations of pulping additives

Reactions of 1-(4-guaiacyl)-2-(O-guaiacyl)-1,5-pentanediol (1) provide information on the relative rates of pulping reactions that involve quinone methides (QMs). Model 1 was reacted with sulfite/anthrahydroquinone (AHQ), sulfide (kraft)/AHQ, and sulfide/sulfite reagent combinations at pH similar to 13. Both sulfite/AHQ and sulfide/AHQ systems enhanced beta-aryl ether cleavage when compared to their individual component systems; the greatest fragmentation was observed for the sulfide/AHQ system. Several hypotheses are proposed for the observed synergism. beta-Aryl ether scission was not affected when sulfite was added to the sulfide (kraft) system. This paper is the second in a three-part study designed to examine beta-aryl ether cleavage in multi-reagent pulping systems (e.g., alkaline sulfite/AQ/methanol [ASAM]).