THE ROLE OF PEROXIDE SPECIES IN THE CARBOHYDRATE DEGRADATION DURING OXYGEN BLEACHING .1. FACTORS INFLUENCING THE REACTION SELECTIVITY BETWEEN CARBOHYDRATE AND LIGNIN MODEL COMPOUNDS

A cellulose model compound, methyl beta-D-glucopyranoside (MGP), was s ubjected to oxygen-alkali treatment in the presence of various kinds o f lignin model compounds. Only in the presence of a lignin model compo und reactive with oxygen, a significant degradation of MGP was observe d and the rate and the extent of its degradation were strongly depende nt on the structure and the amount of a lignin model compound. Depress ion of MGP degradation was found to be achieved by two clearly disting uished mechanisms. One is an enhancement of the degradation of a ligni n model compound without the acceleration of MGP degradation and the o ther is a depression of MGP degradation without significantly deterior ating the degradation of a lignin model compound. An increase in oxyge n 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 belong ed to the latter case. The addition of magnesium sometimes resulted in the acceleration of MGP degradation, depending on its ratio to iron.