Influence of Water Structure on Solvolysis in Water-in-Oil Microemulsions

Article abstract of DOI:10.1021/j100032a041

The kinetics of solvolysis of diphenylmethyl chloride, 4-nitrophenyl chloroformate, benzoyl chloride, p-anisoyl chloride, and bis(4-nitrophenyl)carbonate in water/AOT/isooctane microemulsions with various water/surfactant mole ratios W (AOT = sodium bis(2-ethylhexyl)sulfosuccinate) were interpreted by using a pseudophase model in which the substrates are assumed to be distributed between the isooctane and interface phases.The W-dependence of the intrinsic rate constants k for solvolysis at the interface depends on the solvolysis mechanism: for S_N1 reactions, k decreased with W, which is attributed to decreasing polarity of the interface; contrariwise, S_N2 reactions are accelerated by decreasing W, which is attributed to increasing nucleophilicity of interfacial water.