A comparison of the wavelength-dependent photochemical reactions of ozone with vinyl bromide and fluoride in argon matrices

Abstract

A study of the photolytically-induced reactions of ozone with vinyl bromide and vinyl fluoride, H2CCHX (X = F, Br), in argon matrixes is described, after either red LED (625 nm) or Hg pen lamp (254 nm) irradiation. Products were observed using infrared spectroscopy and identification was aided by 18O labeling experiments. The experimental work was supported by extensive DFT calculations. For vinyl bromide, bromoacetaldehyde was the dominant product despite the fact that acetyl bromide was calculated to be the most energetically favored product. Lesser amounts of bromooxirane and possibly bromovinyl alcohol were observed. These results are in agreement with an earlier study of the photochemical reaction of ozone with vinyl chloride. In contrast, the overall product yield with vinyl fluoride was much lower. Fluorooxirane was the main product with only a hint of fluoroacetaldehyde despite that fact that fluorooxirane was calculated to be higher in energy than either acetyl fluoride or fluoroacetaldehyde.