Studies of tertiary amine oxides. Part 14. Protic solvent effects on the rate of thermal rearrangement of N-(2,4-dinitrophenyl)piperidine N-oxide

Abstract

The rate of rearrangement of N-(2,4-dinitrophenyl)piperidine N-oxide has been studied in 15 hydroxylic solvents. The first-order rate coefficients (k_obs) have been successfully correlated with different solvent parameters. The results are explained in terms of the nucleophilic solvation capability of the solvent which in turn supports the previously proposed three-membered ringactivated complex. Moreover, the role of the HBD ability of the solvent in this reaction is also pronounced, particularly since reaction in alcohols exhibits lower reactivity and higher enthalpy and entropy of activation compared with aprotic solvents.