Computational study of the mechanism of thermal decomposition of xanthates in the gas phase (the Chugaev reaction) |
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Authors: | Ederley Vélez Jairo Quijano Rafael Notario Juliana Murillo Juan F Ramírez |
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Institution: | 1. Laboratorio de Fisicoquímica Orgánica, Facultad de Ciencias, Universidad Nacional de Colombia, Sede Medellín, Apartado Aéreo 3840, Medellín, Colombia;2. Instituto de Química Física “Rocasolano”, C.S.I.C., Serrano 119, 28006 Madrid, Spain |
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Abstract: | A theoretical study on the mechanism of the thermal decomposition of a series of xanthates, O‐alkyl S‐methyl and S‐alkyl O‐methyl dithiocarbonates, has been carried out, and the alkyl groups being ethyl, isopropyl, and tert‐butyl. Kinetically, these xanthates can be classified in two groups: those where the oxygen atom is involved in the bonding changes of the transition state (properly the Chugaev reaction), and those where it is not, O‐alkyl S‐methyl and S‐alkyl O‐methyl dithiocarbonates, respectively. We have studied not only the thermal elimination reactions but also the other possible reactions such as the thione‐to‐thiol rearrangement and the nucleophilic substitution to give ethers or thioethers. Two possible mechanisms for the thermal elimination reactions, in one and in two steps, respectively, have been studied. Calculations were made at the MP2/6‐31G(d) level of theory, and the progress of the reactions has been followed by means of the Wiberg bond indices. Copyright © 2008 John Wiley & Sons, Ltd. |
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Keywords: | Chugaev reaction thermal decomposition gas phase mechanism ab initio |
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