The hydrogenation of coal model compounds using molten potassium and ethanol was carried out with and without ultrasonic irradiation. Aromatic ethers and ploynuclear hydrocarbons were employed as coal model compounds. The cleavage of carbon-oxygen bonds was dominant for the aromatic ethers, whereas main products obtained from the polynuclear hydrocarbons were compounds derived from hydrogenation of the aromatic nucleus. The reaction mechanism was affected by the structure of the substrate: one-electron and/ or two-electron reaction. The effect of ultrasonic irradiation is very small in the reaction of the hydrocarbons. On the other hand, striking effect caused by the ultrasonic irradiation, such as an inccrease of the rate, an increase of the final conversion, and the promotion of sidereactions, ware observed for the reaction of the ethers.
