Rate acceleration of SN2 reactions through selective solvation of the transition state

High level ab initio calculations show that the SN2 reaction of the cyanide ion with ethyl chloride is catalysed by 1,4-benzenedimethanol in dipolar aprotic solvents through selective two hydrogen bonds. In apolar solvents, combined with phase transfer catalysis, the 1,4-benzenedimethanol could replace some water molecules hydrating the cyanide ion and induce a substantial rate acceleration effect.