THERMAL AND PHOTOCHEMICAL DEAZETATIONS OF FLUORINE-SUBSTITUTED 4-METHYLENEPYRAZOLINES. THE KINETIC BEHAVIOR OF TRIMETHYLENEMETHANES.

Article abstract of DOI:10.1021/ja00319a038

4-(Difluoromethylene)-1-pyrazoline and 4-(fluoromethylene)-1-pyrazoline were observed to undergo thermal and photochemical deazetation in the gas phase as well as in solution to form mixtures of methylenecyclopropanes. The gas-phase and solution-phase, thermal, and photochemical results are contrasted, and the observed kinetically controlled product ratios are compared with the very different equilibrium values. As a result, mechanisms involving trimethylenemethane diradicals are proposed for both processes. The photochemical reactions seem to be dominated by 'hot' reactions of vibrationally excited TMMs, while the thermal reactions show interesting selectivity in their cyclization processes.