Basic Ionic Liquid Gels for Catalysis: Application to the Hydrogen Borrowing Mediated Dehydration of 1,3-Propanediol

The application of basic ionic liquid gels (BILGs) as recyclable promoters of hydrogen borrowing chemistry was investigated. The hydrogen transfer initiated dehydration of 1,3-propanediol to propanal was catalyzed by a [Cp*IrCl2(NHC)] complex promoted by BILGs containing [P6,6,6,14]­[OH]. Gels comprising a mixture of basic and hydrophobic ionic liquids gave the best results. The reaction proceeded in the ionic liquid [C2mmim]­[NTf2] enabling the continuous removal of propanal under reduced pressure. Tuning of the composition of the BILG led to a catalytic system that exhibited excellent conversion, selectivity and good recyclability.