Recoil tritium reactions with carbon-carbon single bonds

Abstract

Recoil tritium atoms were allowed to react in hexafluorocyclobutene-moderated systems with hydrocarbons of the general formula R?éü-CH?éâ. The CH?éâT yields per bond from the hot tritium abstraction of end methyl groups from alkanes, alkenes, and alkynes were correlated inversely with the R?éü-CH?éâ bond dissociation energies. Other parameters postulated to control hot atom reactions, such as mass, size, and electron density, were also examined and found not to exert a major influence in determining the CH?éâT yields. On the basis of incomplete employment of allyl resonance in abstraction of the terminal methyl group from 1-butene, the time scale for that and similar reactions was set at 2-5x10?ü????ü? sec. The predominance of chemical parameters in controlling the yields from hot atom reactions suggest that certain collisional complexes can be proposed. In one possible complex, the recoil tritium attacks along the R?éü-CH?éâ bond axis, resulting in a linear complex in which the cleavage of the bond should be the rate-differentiating factor. The other possible complex is triangular in nature, with the recoil tritium attacking in a direction perpendicular to the R?éü-CH?éâ bond; it is the electron overlap process and the C-T bond formation process which should be rate -differentiating in this complex. The experimental findings in this work suggest two different mechanisms for recoil tritium atoms interacting with carbon-carbon single bonds. One mechanism calls for the linear complex to be the major contributor to the CH?éâT yield while the triangular complex accounts for a minor portion..