Catalytic dehydrative etherification and chlorination of benzyl alcohols in ionic liquids

Abstract

Dibenzyl ethers and benzyl chloride can be obtained in moderate to excellent yields through Pd-catalysed reactions in hydrophobic ionic liquids using microwave or conventional heating.

Synthesis of Pd nanocrystals in phosphonium ionic liquids without any external reducing agents

“…During our study of etherification reactions in ILs, 20 upon changing the IL from those containing imidazolium cations to [P 66614 ]DBS (DBS = dodecylbenzenesulfonate) we discovered that the Pd(II)-IL mixtures would change colour over time in the absence of any reagents. We sought to discover the origin of this colour change.…”

Dehydration of Benzyl Alcohols in Phosphonium Ionic Liquids: Synthesis of Ethers and Alkenes

“…In our previous studies, very low conversions were observed in the absence of palladium for dehydrative etherification reactions in imidazolium ionic liquids,5 however, we have since discovered that the reaction can be performed without any metal catalyst in phosphonium ionic liquids (Scheme ). Furthermore, [BMIm]PF 6 was not completely stable under the reaction conditions, as HF was released via hydrolysis of the ionic liquid and our initial studies showed greater stability for phosphonium ionic liquids.…”

“…In some cases, imidazolium ionic liquids have acted as both catalyst and solvent 2–4. Previously, we reported dehydrative etherifications of benzylic alcohols in imidazolium ionic liquids, specifically, [BMIm]PF 6 (1‐butyl‐3‐methylimidazolium hexafluorophosphate) in the presence of Pd catalysts 5. We chose to study such reactions in ionic liquids because these solvents display an exceptional ability to stabilize ionic intermediates.…”

“…Through our previous studies,5 we became interested in using phosphonium ionic liquids as reaction media in the dehydration of benzylic alcohols to yield benzyl ethers and alkenes. Unlike our previous studies using imidazolium ionic liquids, we have since found that there is no need for Pd catalysts in phosphonium ionic liquids for these dehydration reactions and the phosphonium cation can catalyze these reactions.…”

Alcohols in direct carbon-carbon and carbon-heteroatom bond-forming reactions: recent advances

“…Kerton et al reported the procedure based on the utilization of Pd(CH 3 CN) 2 Cl 2 for the etherification of benzyl alcohol in hydrophobic ionic liquids (1-Butyl-3-methylimidazolium hexafluorophosphate, [BMIM]PF 6 ) using a microwave or conventional heating. 147 In the presence of NH 4 Cl chlorination of benzyl alcohol occurred. Palladium on magnesium oxide (Pd/MgO) catalyzed the formation of thioethers from thiols and aldehydes formed in situ from the alcohol by means of a "borrowing hydrogen" method.…”