Nucleophilic character of the tert‐butyl radical. Absolute rate constants for the reactions with substituted toluenes

The decay of photochemically generated tert‐butyl radicals is studied at 48°C in 11 m‐ and p‐substituted toluenes by time‐resolved electron spin resonance spectroscopy. It is governed by the second‐order self‐termination perturbed by a pseudo‐first‐order reaction of the radical with the toluenes. The first‐order lifetimes yield the rate constants kA for hydrogen transfer from toluenes to tert‐butyl. Substituent effects on the rate constants confirm the nucleophilic character of the radical.