Collisional Deactivation of the Excited Singlet Oxygen Atoms and Their Insertion into the CH Bonds of Propane

Abstract

Reaction of the excited singlet oxygen atoms with propane was studied at room temperature and at pressures from 400 to 6400 mm. Three main processes were observed: (1) insertion of the excited singlet atoms into CH bonds, (2) abstraction of hydrogen atoms, and (3) fragmentation of the paraffin. The yields of the insertion products increased approximately linearly with the pressure, the abstraction products remained almost constant and the fragmentation products decreased. The primary step is the insertion of the excited singlet oxygen atoms into the CH bonds of propane to form ``hot'' alcohol molecules. When gases capable of deactivating the excited atoms are added, the insertion and fragmentation decrease and the secondary hydrogen atoms are preferentially abstracted. From the increased discrimination in hydrogen abstraction the following relative rates (k₂/k₃) of the electronic deactivation of the excited singlet oxygen atoms by different gases have been obtained: Xe 0.47, N₂ 0.15, Kr 0.05, and He and SF₆ close to zero.