Nickel—Its intrinsic acidity and its effect on the hydrogenolysis of 1,1-dimethylcyclopropane and ethylcyclopropane

Abstract

The selectivity of hydrogenolysis of 1,1-dimethylcyclopropane and ethylcyclopropane has been studied at 80–150 °C in a pulse-microreactor at atmospheric pressure in the presence of hydrogen and nickel containing catalysts. The method of preparation of the catalysts and the supports used can influence the selectivity of 1,2- and 2,3-ring rupture. In the hydrogenolysis of 1,1-dimethylcyclopropane it was found that nickel oxide catalyst reduced at 400 °C yielded a ratio of neopentane/isopentane equal to 0.9 and 3.6, at 80 and 120 °C, respectively. A similar catalyst containing 0.05% Na + gave ratios of 5.4 and 10.1. Nickel-kieselguhr 6% catalyst gave a ratio of neopentane/isopentane of 1.3 at 80 °C. With catalyst containing 0.1% Na + the ratio was 6.1, and with 1.0% Na + it amounted to 10.5. The incorporation of 0.05% of alumina to 6% nickel-silica catalyst greatly enhances the 1,2-ring scission. Ethylcyclopropane is less sensitive to the changes in the properties of the nickel catalyst. Mechanism of reaction is discussed and it was shown that the enhancement of 1,2-ring scission can be attributed to the intrinsic acidic sites of the catalysts.