37694-11-4Relevant articles and documents
REACTION D'OXIMATION DES CETONES V. MECANISME ET EFFETS DE STRUCTURE DANS LA REACTION DE DESHYDRATATION ACIDO-CATALYSEE DES CARBINOLAMINES
Lamaty, G.,Roque, J. P.,Natat, A.,Silou, T.
, p. 2667 - 2676 (2007/10/02)
The equilibrium constants of formation and the rate constants of dehydratation of carbinolamines resulting from the addition of hydroxylamine to 19 ketones, - 5 aliphatic, 5 aromatic and 9 cyclanic -, have been measured at 25 deg C in water/methanol 60/40 v/v.We show that the acid catalyzed process predominates in the range of pH 6 to 7 for acetophenones or pH 7 to 8.5 for saturated ketones.The rate constants ratios and Hammett ρ constant of the reaction suggest an sp3 (early) transition state.The changes in rate constant are discussed in terms of torsional and non-bonding steric effects.For several hindered ketones, e.g. 3,3,5,5-tetramethylcyclohexanone, we show the existence of a steric hindrance to the approach of the catalyst; in that case the result is a strong decrease of the rate of the dehydratation.
Reactions d'addition nucleophile sur les cetones. Influence de l'environnement sterique sur la position de l'etat de transition
Boyer, B.,Lamaty, G.,Moreau, C.
, p. 272 - 274 (2007/10/02)
In the present investigation, we have measured the secondary kinetic deuterium isotope effects in hydroxylamine addition reaction for a series of cyclohexanones, both hindered and unhindered.We observed a slightly direct isotope effect kH/ksup
