Estimation of atmospheric lifetimes of hydrofluorocarbons, hydrofluoroethers, and olefins by chlorine photolysis using gas-phase NMR spectroscopy

An empirical correlation has been derived between accepted atmospheric lifetimes of a set of hydrofluorocarbons and hydrofluoroethers and relative rates of reaction with photolyzed chlorine in excess at ambient temperature. These kinetic systems were studied by nuclear magnetic resonance (NMR) spectroscopy in the gas phase, marking the first application of NMR spectroscopy to this field. The square of the Pearson coefficient R for the linear correlation between observed reaction rates and accepted atmospheric lifetimes was 0.87 for compounds of lifetime less than 20 years. The method was extended to the study of ethene and propene; the rate of reaction of propene was found to be 1.25 times that of ethene at 23 degrees C. The chief advantage of this method is its simplicity and reliance only on common tools and techniques of an industrial chemical laboratory.