The effects of substrate, solvent, and structure on reactions of thiols with quinones

Nearly a decade ago, we found that some sulfur-containing compounds, such as thioglycerol, are effective at bleaching and stabilizing high-yield pulps against photoinduced yellowing. In more recent work, we examined the reactions in solution of thioglycerol with several lignin model quinone compounds [1]. In the study presented here, we examined the same reactions using cellulose fibers as our substrate. While the products are generally the same as those found in solution, the product ratios are substantially different. We also investigated solvent effects by using both water and methanol as solvents. We are now examining the effect of thiol structure using model quinone compounds and several structurally related thiols. In combination with the experimental work, we are doing molecular modeling to explore the reasons for the reactivity differences among thiols in the bleaching reaction, as well as the relative stabilizing abilities of these compounds.