Catalytic Polymerization of Hydroquinone by Primary Minerals1

We investigated the catalytic effects of olivines, amphiboles, pyroxenes, micas, feldspars, and quartz on the polymerization of hydroquinone. The primary minerals studied differ in their ability to accelerate the abiotic polymerization of hydroquinone. The catalytic effect of tephroite, which is an Mn-bearning silicate, is greatest among the minerals studied, followed by actinolite, hornblende, fayalite, augite, biotite, and muscovite ≅ albite ≅ orthoclase ≅ microcline ≅ quartz. The SEM micrographs and IR spectrum of the hydroquinone polymers synthesized in the tephroite system are similar to those of naturally occurring humic substances. Tephroite converts a considerable amount of hydroquinone to humic acid with a high degree of humification (Δ log K: 0.43; RF: 132). The data obtained in the present study indicate that the catalytic effects of various primary minerals, especially Mnbearing silicates, on the abiotic formation of humic substances in the environments should not be overlooked, for primary minerals are the rock-forming minerals on the earth and are common in soils and aquatic sediments.