Radicals derived from N-methylmorpholine-N-oxide (NMMO): structure, trapping and recombination reactions

The two carbon-centered radicals 4-morpholinomethyl () and 4-methylmorpholin-3-yl (), generated from the primary cation radical intermediate by β-deprotonation, are the major radical species in reaction mixtures of N-methylmorpholine-N-oxide () as demonstrated by trapping reactions with γ-tocopherol. Carbon–carbon coupling products originating from the recombination of and the reaction between and have been identified. Recombination of with the primary cation radical was shown to be the key step in the ‘disproportionation’ of into N-methylmorpholine, morpholine and formaldehyde.