1,2-H SHIFT IN BENZYLCHLOROCARBENE - ISOTOPE EFFECT AND INFLUENCE OF THE SOLVENT

Laser flash photolysis of 3-chloro-3-benzyldiazirine and 3-chloro-3-(p henyldideuteriomethyl)diazirine in isooctane over the 60 to -80-degree s-C temperature range gives rise to curved Arrhenius plots for both 1, 2-H and 1,2-D migration in benzylchlorcarbene. The k(H)/k(D) values in crease smoothly from 0.87 to 2.62 when the temperature increases from -60 to +30-degrees-C. The k(H)/k(D) value is approximately 4 for most of the temperatures studied if a solvent correction is applied. Quantu m mechanical tunnelling or the influence of the solvent may be a possi ble explanation for these observations.