The hydrogen bond acidity and other descriptors for oximes

Abstract

The solvation descriptors for cyclohexanone oxime and acetone oxime have been obtained from measurements on water–solvent partitions, and gas–liquid chromatographic retention data. These yield values of 0.33 and 0.37 for the Abraham hydrogen bond acidity, A, in reasonable agreement with a value of 0.37 for cyclohexanone oxime obtained by our recent NMR method. The other descriptors E, S, B, L and V have also been obtained for cyclohexanone oxime and acetone oxime, and have been estimated for a number of other oximes as well. The value for A, the overall or effective hydrogen bond acidity of the oximes is reasonably close to the 1 : 1 hydrogen bond acidity, α₂^H = 0.39 to 0.46, that can be deduced from previous literature measurements on oximes, and to the 1 : 1 hydrogen bond acidity, α₂^H = 0.43 for another NOH compound, N,N-dibenzylhydroxylamine, that again can be deduced from literature measurements.