The photochemistry of ethyl chloride

Abstract

Ethyl chloride and deuterium-labelled ethyl chlorides have been photolyzed at 184.9, 163.3, 147.0 and 123.6 nm in the gas phase and at 163.3 and 147.0 nm in the liquid phase. The use of NO, O 2 and HI as radical scavengers has permitted a determination of the quantum yields of primary photodecomposition processes as a function of wavelength. At low energies, excitation of an electron into an antibonding σ* orbital leads primarily to CCl bond cleavage, while at higher energies this process is largely replaced by loss of HCl and hydrogen. Both 1,1- and 1,2-HCl eliminations are observed. The absence of significant amounts of hydrogen atom production at 163.3 nm and at low pressures suggests that one excited state may be responsible for HCl elimination and a second for chlorine atom loss, in agreement with the mechanism of Ichimura .