Studies in energy transfer II. The isomerization of cyclo propane—a quasi-unimolecular reaction

The thermal isomerization of cyclopropane to propylene is a homogeneous unimolecular reaction at 490° C and at pressures down of 0·007 cm. The rate constant of the unimolecular reaction falls off by a factor of ten as the pressure in the reaction system is decreased from 8·4 to 0·007 cm. The results are compared with various theories of quasi-unimolecular reactions. The addition of a non-reacting gas to the system counteracts the falling off. The relative efficiencies of a number of gases for maintaining the unimolecular rate constant have been measured.