Comparison with phase-transfer, micellar

Comparison with Phase-Transfer, Micellar and Other Biphasic Techniques... 

There has been a useful review of phase-transfer catalysis in nucleophilic aromatic substimtion. A comparison has been reported of the reactions with nucleophiles of l-chloro-2,4-dinitrobenzene (substimtion) and 4-nitrophenyl diphenyl phosphate (dephosphorylation) in neutral micelles of dodecyl (10) and (23) polyoxyethylene glycol. In the substimtion reaction considerable amounts of ether may be formed by reaction with alkoxide ions at the micellar surface. Differences in reactivity of the two substrates are probably due to differences in their location in the micellar structures. ... 

A comparison of the constant k K with k is dependent upon the choice of standard state because the micelle catalysed reaction is a higher order process. For a bimolecular reaction within the micelle, k K, has units of concentration time and represents the free energy difference between the reactants and micelle in the bulk aqueous phase and the transition state in the micellar phase. The analogous reaction in the absence of micelles proceeds with a rate constant k with units of concentration time . The ratio k KJk has units of concentration and represents the free energy of transfer of the transition state from the aqueous phase to the micellar phase. 

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