Effect of fluorination on thiol reactivity: Reaction of 4,4, 4-trifluorobutanethiol on Mo(110)
- Harvard Univ., Cambridge, MA (United States)
The reaction of 4,4,4-trifluorobutanethiol on Mo(110) was studied using temperature-programmed reaction, Auger electron, and infrared spectroscopies. The dominant decomposition pathway for CH{sub 3}(CH{sub 2}){sub 3}S-, CF{sub 3}(CH{sub 2}){sub 3}S-, and CF{sub 3}CH{sub 2}S- is C-S bond hydrogenolysis at approximately 300 K to form butane, trifluorobutane, and trifluoroethane, respectively. A secondary pathway is alkene elimination from CH{sub 3}(CH{sub 2}){sub 3}S-, CF{sub 3}(CH{sub 2}){sub 3}S- and CF{sub 3}CH{sub 2}S- to form butene, trifluorobutene, and difluoroethylene, respectively, over a wide temperature range, 200-500 K. The primary difference in the chemistry comparing the two C{sub 4} thiolates, the fluorinated and nonfluorinated, is the observation of difluoroethylene from CF{sub 3}(CH{sub 2}){sub 3}S- at 540 K. No ethylene or other hydrocarbon products were formed at such high temperatures in the reactions of CF{sub 3}(CH{sub 2}){sub 3}S-. The observation of difluoroethylene from the reaction of CF{sub 3}(CH{sub 2}){sub 3}S- is most likely due to a difference in the competing rates of complete decomposition and selective elimination. The increased strength of C-F relative to C-H bonds, and the increased strength of the C-C and C-H bonds adjacent to the trifluoromethyl group, may help to preserve a fluorocarbon intermediate, possibly trifluoroethyl, up to the more elevated temperatures such that difluoroethylene is formed. 30 refs., 5 figs., 4 tabs.
- DOE Contract Number:
- FG02-84ER13289
- OSTI ID:
- 232525
- Journal Information:
- Langmuir, Journal Name: Langmuir Journal Issue: 7 Vol. 12; ISSN 0743-7463; ISSN LANGD5
- Country of Publication:
- United States
- Language:
- English
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