Examining the Influence of Anion Nucleophilicity on the Polymerisation Initiation Mechanism of Phenyl Glycidyl Ether.

The reaction of phenyl glycidyl ether (PGE) with 1-ethyl-3-methylimidazolium acetateand 1-ethyl-3-methylimidazolium thiocyanate to initiate the polyetherification reaction wasexamined using thermal and spectral analysis techniques. The influence of the nucleophilicity of theanions on the deprotonation of the 1-ethyl-3-methylimidazolium cation determined the reactionpathway. The thermal degradation of the ionic liquid liberated the acetate ion and led, subsequently,to the deprotonation of the acidic proton in the imidazole ring. Thus, polymerisation of PGEoccurred via a carbene intermediate. The more nucleophilic thiocyanate anion was not sufficientlybasic to deprotonate the 1-ethyl-3-methylimidazolium cation, and thus proceeded through directreaction with the PGE, unless the temperature was elevated and a competing carbene mechanismensued.