Nitrogen inversion and N–O bond rotation processes in di-and tri-substituted hydroxylamines. A dynamic NMR study

Abstract

The barriers to inversion in several acyclic di- and tri-substituted hydroxylamines are determined by ¹H NMR band shape analysis. The barriers range from 49.1 to 66.8 kJ mol^–1 and are discussed in terms of a conformational process which involves nitrogen inversion and rotation around the N–O bond. The N–benzyl group with an ortho hydroxy substituent increases the nitrogen inversion barrier by 10 kJ mol^–1, which indicates the requirement of breaking of the intramolecular hydrogen bond prior to inversion.