Reactions d'addition nucléophile sur les cétones. Rǒle des facteurs stériques à longue distance dans les réactions d'addition de l'ion sulfite et de l'hydroxylamine

Rate constants have been measured for the addition of sulphite ion and hydroxylamine on a series of sterically hindered cyclohexanones as well as for the decomposition of the bisulphite adducts. The observed differences in reactivity mau be regarded as resulting from the intervention of the “steric compression effect” due to the axial substituents. Calculated δΔG≠ values confirm the existence of such an effect and the results are consistent with the intermediate formation of a “reactant-like” transition state in these reactions.