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Mercury photosensitized reactions of fluoromethanes

Mercury photosensitized reactions of fluoromethanes
Mercury photosensitized reactions of fluoromethanes

The efficiency with which hydrogen quenches excited mercury 6( P ) atoms to the ground state is very much greater than that for the fluoromethanes. Consequently for approximately 1:1 mixtures of hydrogen with fluoroform, difluoromethane or methyl fluoride, only quenching by hydrogen to yield hydrogen atoms is important. In this way, hydrogen abstraction from the fluoromethanes was studied, the final product in all three cases being almost entirely methane. The activation energy for hydrogen abstraction from fluoroform by hydrogen atoms was found •V a. 1 to b e 9 .4 kcdLmole . The existence of methylene Intermediates, formed by the elimination of hydrogen fluoride from chemically activated fluoromethanes, is suggested, and possible reaction mechanisms are discussed. Chemical quenching of excited mercury atoms by methyl fluoride was observed in the absence of added hydrogen, and the quenching mechanism is discussed in terms of a collision complex between mercury and methyl fluoride. The formation of products was studied as a function of time, temperature and pressure, and appeared to proceed by two

University of Southampton
Allen, John Douglas
Allen, John Douglas

Allen, John Douglas (1968) Mercury photosensitized reactions of fluoromethanes. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The efficiency with which hydrogen quenches excited mercury 6( P ) atoms to the ground state is very much greater than that for the fluoromethanes. Consequently for approximately 1:1 mixtures of hydrogen with fluoroform, difluoromethane or methyl fluoride, only quenching by hydrogen to yield hydrogen atoms is important. In this way, hydrogen abstraction from the fluoromethanes was studied, the final product in all three cases being almost entirely methane. The activation energy for hydrogen abstraction from fluoroform by hydrogen atoms was found •V a. 1 to b e 9 .4 kcdLmole . The existence of methylene Intermediates, formed by the elimination of hydrogen fluoride from chemically activated fluoromethanes, is suggested, and possible reaction mechanisms are discussed. Chemical quenching of excited mercury atoms by methyl fluoride was observed in the absence of added hydrogen, and the quenching mechanism is discussed in terms of a collision complex between mercury and methyl fluoride. The formation of products was studied as a function of time, temperature and pressure, and appeared to proceed by two

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Published date: 1968

Identifiers

Local EPrints ID: 460304
URI: http://eprints.soton.ac.uk/id/eprint/460304
PURE UUID: 021acb56-656f-4b29-aabf-398af0924c4b

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Date deposited: 04 Jul 2022 18:18
Last modified: 04 Jul 2022 19:25

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Contributors

Author: John Douglas Allen

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