Catalytic Polymerization of Phenolic Compounds by Clay Minerals

A solution of phenolic compounds was added separately to montmorillonite, illite, and kaolinite, each of which had been mixed with quartz in a 3:7 ratio, and to pure quartz. The oxidative polymerization took place at once and was allowed to proceed for 10 days. The humic and fulvic acids were found largely in montmorillonite and illite and much less so in kaolinite and quartz. Their infrared spectra resemble those of the natural products. The amounts of oxygen absorbed by 0.5 ml M pyrogallol solution buffered at pH 5.3 in the absence and presence of various clay minerals and quartz were determined by a Warburg instrument. The results show that all of the clay minerals and quartz catalyze the oxidative polymerization of pyrogallol. Contaminated Fe and Al bear significant correlation with the catalysis. Among the minerals tested, the catalytic oxidation power decreases in the following order: 2:2 > 2:1 > 1:1 > quartz. The organomineral complexes formed were darker in color when 2:2 and 2:1 minerals were used, particularly in the presence of contaminated Fe and Al. The probable mechanism of the catalysis is briefly discussed.