RATES OF TERMINATION OF RADICALS IN SOLUTION .3. SEMIDIONE RADICALS

The bimolecular radical decay rates for the semidione radicals derived from a series of nine α-diketones have been determined in isopropyl alcohol by a light intermittency-esr technique. Two classes of radicals are recognized: Those derived from rigidly cis, sterically hindered α-diketones (1-4), which decay by disproportionation and have decay rate constants about 1-4 × 107 M−1 sec−1, and those derived from flexible α-diketone, which terminate by coupling and show decay rates about 2-4 × 10−8 M1 sec−1. © 1969, American Chemical Society. All rights reserved.