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Computational study of the mechanism of thermal decomposition of xanthates in the gas phase (the Chugaev reaction)
Author(s) -
Vélez Ederley,
Quijano Jairo,
Notario Rafael,
Murillo Juliana,
Ramírez Juan F.
Publication year - 2008
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1383
Subject(s) - chemistry , alkyl , isopropyl , thermal decomposition , nucleophile , medicinal chemistry , decomposition , nucleophilic substitution , gas phase , reaction mechanism , computational chemistry , transition state , organic chemistry , catalysis
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.