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Title

A Matrix Isolation Study Of The Reactions Of Oxygen(Singlet-D) With The Chlorofluoromethanes Fluorotrichloromethane, Dichlorodifluoromethane And Chlorotrifluoromethane

Date of Award

1981

Document Type

Dissertation

Abstract

We have studied the reactions of O(('1)D) with CCl(,3)F, CCl(,2)F(,2) and CClF(,3) in CO(,2), SF(,6) and N(,2)O matrices, and in neat mixtures. Photolysis of cryogenic mixtures of ozone and the chlorofluoromethanes in various matrix hosts resulted in production of O(('1)D) which migrated through the matrix to react with the Freon molecules. Products were detected by infrared spectroscopy of the matrix deposits, with assignments confirmed by comparison of ('16)O and ('18)O absorption bands with literature values. Evidence for oxygen atom insertion into a C-Cl bond to form a hypochlorite intermediate was obtained. In the case of CCl(,3)F, the first stable product to be formed was COClF, but this subsequently photo-oxidized to give COF(,2) and CO(,2). In addition, evidence for fluorine atom reactions with the substrate was found in the formation of CCl(,2)F(,2) from CCl(,3)F. In the case of the reactant CCl(,2)F(,2), the major products were COF(,2) and CO(,2), followed by the product of F-atom reactions, CClF(,3). For both of these chlorofluoromethanes, since COF(,2) does not react with O(('1)D), the most likely source of F-atom chemistry was concluded to be the reaction that also forms CO(,2). In the case of the reactant CClF(,3), the major product was COF(,2), which would form together with ClF, thus providing a source for flourine atoms. CO(,2) was also found in the deposit after photolysis, although its presence cannot be explained definitively. Additional new features in the spectra of the product mixtures for this system have been tentatively assigned to CF(,3)OCl and CF(,3)OOCF(,3).

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