The bleaching and photostabilization of high-yield pulp by sulfur compounds .1. Reaction of thioglycerol with model quinones

The reaction of thioglycerol with quinones selected to model the chromophores present in high-yield pulp has been investigated. The reaction is rapid and complex, involving initial Michael addition, aromatization of the adducts to hydroquinones, and reoxidation of those hydroquinones to new chromophores. The Michael addition is responsible for the bleaching effect of thioglycerol upon pulp, and the reoxidation is responsible for the eventual development of more intense color by treated pulp. Semi-empirical and ab initio molecular orbital calculations have been used as an aid to rationalizing the experimental results.