Kinetic Studies on the Addition of Thiophenol to ￥á, N-Diphenylnitrone

摘要

The rate constants for the nucleophilic addition of thiophenol to メ, N-diphenylnitrone and it`s derivatives (p-OCH3, p-Cl, p-NO2) were determined from pH 3.0 to 13.0 by UV spectrophotometry and rate equations which can be applied over a wide pH range were obtained. On the basis of rate equation, general base and substituent effect a plausible addition mechanism of thiophenol to メ, N-diphenylnitrone was proposed: At high pH, the addition of sulfide ion to carbon-nitrogen double bond was rate controlling, however, in acidic solution, reaction was proceeded by the addition of thiophenol molecule to carbon-nitrogen double bond after protonation at oxygen of メ, N-diphenylnitrone.