Cinetique complexe de l'halogenation de cetones en milieu acide—II : Controle par la diffusion des vitesses d'halogenation des enols-consequences |
| |
Authors: | JE Dubois J Toullec |
| |
Institution: | Laboratoire de Chimie Organique Physique de l''Université de Paris VII, associé au CNRS, 1, rue Guy de la Brosse, 75005 Paris, France |
| |
Abstract: | The kinetics of the bromination and chlorination of acetone, diethylketone and di-isopropylketone (bromination only) have been studied at X2]ao ≈ 10?7 to 10?5 M; the apparent rate constants kIIX2 = KEk2X2 (where KE is the keto-enol equilibrium constant) for iodination, bromination and chlorination are approximately equal. This result is attributed to diffusion-controlled kinetics. The order of magnitude of such a limiting rate constant, 109 M?1s?1 calculated from Smoluchowski's equation, leads to new values for KE in solution (1·5 x 10?8 for acetone) much smaller than those in the literature. The rate constants derived for enol ketonisation are then in good agreement with those from proton addition to the corresponding enol ethers. |
| |
Keywords: | A qui doit être adressée toute correspondance |
本文献已被 ScienceDirect 等数据库收录! |
|