Preparation of some polymer-supported crown ethers and their use as phase-transfer catalysts

Abstract

Benzo-15-crown-5 and dibenzo-18-crown-6 have been formylated. The products were then bound to diol-containing crosslinked polystyrenes via acetalisation and to crosslinked polymers containing benzyltriphenylphosphonium chloride residues (obtained by treating chloromethylated polystyrenes with triphenylphosphine)via phase-transfer catalysed Wittig reactions. The various polymer-supported crown ethers have been found to be satisfactory phase-transfer catalysts for the reactions of n-octyl bromide in toluene with aqueous potassium iodide at 90 °C and with aqueous sodium p-methylthiophenolate at 80 °C, but not for the reaction of n-octyl bromide in toluene with aqueous potassium cyanide at 90 °C. The crosslinked polymers containing benzyltriphenylphosphonium chloride residues were also satisfactory catalysts for the first two reactions.