1. Factors Influencing the Reaction Selectivity between Carbohydrate and Lignin Model Compounds

ABSTRACT

A cellulose model compound, methyl β-D-glucopyranoside (MGP), was subjected to oxygen-alkali treatment in the presence of various kinds of lignin model compounds. Only in the presence of a lignin model compound reactive with oxygen, a significant degradation of MGP was observed and the rate and the extent of its degradation were strongly dependent on the structure and the amount of a lignin model compound. Depression of MGP degradation was found to be achieved by two clearly distinguished mechanisms. One is an enhancement of the degradation of a lignin model compound without the acceleration of MGP degradation and the other is a depression of MGP degradation without significantly deteriorating the degradation of a lignin model compound. An increase in oxygen pressure and a 10% methanol addition belonged to the former case and a change in the ratio of metal ions and a 1% methanol addition belonged to the latter case. The addition of magnesium sometimes resulted in the acceleration of MGP degradation, depending on its ratio to iron.