Improved Synthesis of 1‐Hydroxy‐2,2,5,5‐tetramethyl‐3‐imidazoline 3‐Oxide (HTIO)

Abstract

Abstract A simple, efficient, mild, and reproducible method for the synthesis of 1‐hydroxy‐2,2,5,5‐tetramethyl‐3‐imidazoline 3‐oxide is described. The method is based on the condensation of 2‐hydroxyamino‐2‐methylpropanal oxime with 2,2‐diethoxypropane in the presence of an equimolar quantity of acetic acid. Cost‐effectiveness of the condensation procedure could be also achieved by replacing 2,2‐diethoxypropane with less expensive 2,2‐dimethoxypropane. Keywords: Aldonitrone, 2,2‐dialkoxypropane, HTIO, 3‐imidazoline 3‐oxide, nitroxide Acknowledgments We thank Elena I. Chernyak (Novosibirsk) for technical assistance in HPLC experiments. Authors acknowledge the contribution made by Dmitry G. Mazhukin for assistance with the NMR spectra acquisition.