BIMOLECULAR FORMATION OF RADICALS BY HYDROGEN TRANSFER .9. UNCATALYZED TRANSFER HYDROGENATION OF ALPHA-METHYLSTYRENE BY 9,10-DIHYDROACRIDINE AND N-METHYL-9,10-DIHYDROACRIDINE

Hydrogen is transferred from acridane (1c) and N-methylacridane (1d) t o alpha-methyl-styrene (2) in a bimolecular uncatalyzed reaction at 26 0-300 degrees C. On the basis of the activation parameters (for 1c: De lta H double dagger = 29.0 kcal/mol, Delta S double dagger = -23.5 e.u . in triglyme) the kinetic isotope effect (k(H)/k(D) - 2.0, in triglym e at 300 degrees C) as well as the small solvent effects and from the observation of an EPR signal of N-methylhydroacridyl radicals a three- step radical mechanism is proposed which is initiated by a retrodispro portionation between 1 and 2.