Chlorofluorocarbon CFCs, potential alternative HCFCs and HFCs, and related chlorinated compounds: mass spectral study, Part II.

In a previous publication, mass spectrometry was applied to the study of several ions formed by dissociative ionization of ethanes, partially substituted with fluorine and chlorine, and to the determination of the fragmentation pattern of each related compound. The aim of the present investigation was to extend this mass spectral study (70 eV and low ionization energy) to a group of closely related analogs, hydrofluorocarbons (HCFCs), HFCs, chlorinated fluorocarbons, and chlorinated hydrocarbons--halogenated methane, ethane, and propane molecules--to make an attempt to predict the relative bond strength and then the behavior--metabolic pathway and tropospheric degradation--of new HCFCs and HFCs.

Mass spectral study of chlorofluorocarbons (CFCs) and potential alternatives (HCFCs and HFCs).

Owing to high ozone depletion potential of the chlorofluorocarbons (CFCs), the production of such substances has been regulated worldwide by the Montreal Protocol in 1987. There is an urgent need to find other suitable products to replace them and hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are considered to be the most probable candidates as CFC alternatives. The HCFCs and HFCs are more susceptible to decomposition during use than CFCs because they contain hydrogen. Toxicological data on these alternative fluorocarbons are being developed. A systematic investigation of these compounds has been undertaken to establish the fragmentation patterns. Electron impact mass spectra are reported for HCFCs and HFCs. Fragmentation mechanisms are presented and discussed on the basis of variable energy (11 to 30 eV) spectra. At low ionization energy, it is possible to describe an order of fragmentation for each compound. This may lead to the possibility of classifying them according to characteristic behaviors.