Exchange reactions of 2,2-dimethylpentane, 2,2-dimethylbutane and 2,2-dimethylpropane over Pt/SiO2 and Rh/SiO2

Abstract

A comparison has been made of the exchange reactions of deuterium with 2,2-dimethylpentane (22DMP), 2,2-dimethylbutane (22DMB) and 2,2-dimethylpropane (DMP) over Pt/SiO₂ to investigate the mechanisms which allow exchange to propagate across the quaternary carbon atom. The contribution of this process increases with the temperature and is augmented by an increase in the size of the alkyl group attached to the tert-butyl group. Results were also obtained with Rh/SiO₂ for comparison.

Deuterium NMR analyses were made on the products from the exchange of 22DMP over both metals and these proved helpful as a guide to possible mechanisms, particularly with Rh/SiO₂.