Abstract

Chlorinated Halocarbons and chlorofluorocarbons (CFCs) have become synonymous with environmental destruction, ozone depletion and the greenhouse effect. HCFCs (hydro chlorofluorocarbons) and HFCs (hydro fluorocarbons) became the interim replacements for CFCs when the Montreal Protocol banned them in 1987. However, these molecules have their own hazardous implications, specifically as greenhouse gases. It is for these reasons that HCFC and HFC compounds will be phased out by 2020 in developed countries and 2030 in developing nations. The cleanup or conversions of these molecules into feedstock are therefore a major priority and point of study. The in lab study of these numerous compounds to determine their degradation processes and how they react in the atmosphere has become vital to the preservation of the environment and the future of our planet. CD3CD2CHF2 is the focus of this study because it is a suitable model for many HFC’s that will be banned in 2020. Photolysis of CD3CD2I and CHF2I in Pyrex vessels with some Hg2I2 using an ultraviolet lamp forms HgI2 and the CD3CD2 and CHF2 radicals that combine to produce chemically activated CD3CD2CHF2. Reaction vessels, over a range of pressures, contained approximately a 4:1.5 ratio of CD3CD2I and CHF2I were prepared. A Gas Chromatographer Mass Spectrometer was used for product analysis. The 1,2-DF elimination forms E and Z-CD3CD=CHF favoring the E-isomer. The 1,1-HF elimination reaction forms the CD3CD2CF: carbene that may transfer a D giving E and Z-CD3CD=CDF also favoring the E formation at certain pressures. It was also found that not all carbene has the energy to undergo D migration and stays in the unstable form. Trapping the unstable carbene with a scavenger was also studied. The competition between the 1,2- and 1,1-HF/DF elimination, the results from DFT calculations for the various reaction channels, and the molecules carbene chemistry will be discussed.

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