Unexpected Microwave Reaction of 1,3‐Disubstituted Imidazolium Salts: A Novel Synthesis of 1,3‐Disubstituted Imidazole‐2‐thiones
作者:Xiao‐Le Tao、Ming Lei、Yan‐Guang Wang
DOI:10.1080/00397910601038947
日期:2007.2.1
Abstract Microwave‐promoted reaction of 1,3‐disubstituted imidazolium salts with potassium thioacetate or potassium thiocyanate under solvent‐free conditions provided a rapid and efficient synthesis of 1,3‐disubstituted imidazole‐2‐thiones.
Reaction of elemental chalcogens with imidazolium acetates to yield imidazole-2-chalcogenones: direct evidence for ionic liquids as proto-carbenes
作者:Héctor Rodríguez、Gabriela Gurau、John D. Holbrey、Robin D. Rogers
DOI:10.1039/c0cc05223j
日期:——
Mechanistic analysis of the reaction between elemental sulfur or selenium and 1,3-dialkylimidazolium acetate ionic liquids, in the absence of an external base or solvent, affords evidence for the equilibrium presence of carbene species in these ionic liquids. It demonstrates the potential to control, through anion selection, the concentration of carbene in stable ionic liquids.
An Efficient Combined Electrochemical and Ultrasound Assisted Synthesis of Imidazole-2-Thiones
作者:Marta Feroci、Monica Orsini、Achille Inesi
DOI:10.1002/adsc.200900359
日期:2009.9
The electrochemical reduction of 1,3-dialkylimidazolium ionic liquids gave the corresponding N-heterocyclic carbenes that, after reaction with elemental sulfur and ultrasound irradiation, yielded 1,3-dialkylimidazole-2-thiones in very high yields. The reaction is very clean, produces no side-products and avoids the use of any other added reagent.
limited thermal stability which resulted in the formation of an imidazole 2-thione and a new sulfide ionicliquid. Conversely, the formation of the imidazole 2-thione was not observed when phosphonium disulfide ILs were heated, thus confirming the involvement of the imidazolium ring in an unexpected side reaction. An insight into the mechanism of the decomposition has been provided by means of DFT calculations
The reaction of 1-ethyl-3-methyl-4-imidazoline-2-thione with methyliodide followed simple second order kinetics in polar solvents, whereas in less polar solvents the reverse process made a significant contribution to the overall rate. The solvent effects on the forward rate constant were linearly related to those on the rate of the reaction of tetramethylthiourea with methyliodide. A plot of ΔV0\eweq