Heterogeneously catalysed selective hydrogenation reactions in ionic liquids

Abstract

The selective hydrogenation of a,b unsaturated aldehydes has been performed in a range of room temperature ionic liquids. The reaction data reported show that it is possible to enhance the selectivity of supported palladium catalysts for the reduction of the conjugated CNC bond by using ionic liquids as solvents compared with conventional molecular organic solvents. The catalyst system is easily recycled without the need to isolate or filter the catalyst and may be used without further treatment.

Solid Catalyst with Ionic Liquid Layer (SCILL) – A New Concept to Improve Selectivity Illustrated by Hydrogenation of Cyclooctadiene

“…For applications of ILs in the field of catalysis, two directions recently discussed in the literature are particularly attractive: -ILs are not only interesting solvents for homogeneous catalysis but also for heterogeneously catalyzed reactions [19][20][21]. For example, Xu et al [21] showed that ILs are excellent media for the hydrogenation of halonitrobenzenes to the corresponding haloanilines over Raney nickel, carbon-supported platinum and palladium.…”

Biodegradable, non-bactericidal oxygen-functionalised imidazolium esters: A step towards ‘greener’ ionic liquids

“…The product was then dried under high vacuum for 4 h to give viscous liquid at 20 • C in 91% yield (3.87 g, 9.97 mmol). 1 …”

“…The product remaining was dried on the rotary evaporator and then under high vacuum for 8 h to yield a yellow grease in 85% yield (3.33 g, 7.62 mmol). 1 …”

Hydrogenation in Ionic Liquids

“…The reaction rates were found to be lower in [bmim] [BF 4 ] than in methanol, which was attributed to mass transfer processes. Anderson et al [43] selected the , -unsaturated aldehydes, citral and cinnamaldehyde ( Figure 9 and Figure 10), to demonstrate the superior selectivity obtained using pyridinium, imidazolium and ammonium ILs over common organic solvents in hydrogenation reactions. A palladium on carbon catalyst (3) was used for the reactions.…”