Probing the internal competition between alpha- and beta-elimination by fluorine substitution in adsorbed ethyl groups on Cu(100).

Key factors affecting the competition between alpha- and beta-elimination channels for adsorbed ethyl groups on a metal surface were probed by fluorine substitution. The thermal desorption products and temperatures resulting from ethyl, 2,2,2-trifluoroethyl, 1,2,2,2-tetrafluoroethyl, 1,1,2,2-tetrafluoroethyl, and pentafluoroethyl moieties adsorbed on Cu(100) provided the information about the dominant reactions and a measure of the relative rates. The alterations of number and positions of the fluorine substituents revealed that the eclipsed interactions and hyperconjugation in the transition states can determine the kinetic barriers and allowed access to the separate pathways.

A unique reaction pathway of fluorine-substituted ethyl groups on Cu(111): successive alpha,alpha-fluoride elimination.

Fluorine-substituted ethyl groups on Cu(111) were generated by thermal scission of the C-I bond in the adsorbed C2F5I. Temperature-programmed reaction spectrometry observed a novel pathway resulting in the evolution of C4F6 above 400 K. Among the various isomers, this product was identified as hexafluro-2-butyne.