Nucleophilic Aromatic Substitution in Microemulsions

Article abstract of DOI:10.1021/j100222a032

The rate constants of reaction of 2,4-dinitrofluorobenzene(DNF) with OH- in microemulsions of n-octane, tert-amyl alcohol, and cetyltrimethylammonium bromide (CTABr) and in micelles of CTABr and tert-amyl alcohol can be treated quantitatively by using a pseudophase ion-exchange model and the second-order rate constants in the microemulsion or micelle droplets are larger than that in water, but much smaller than those in moist tertiary alcohols.Reactions of DNF and 2,4-dinitrochlorobenzene (DNC) in microemulsions or micelles containing primary alcohols (n-butyl or benzyl alcohol) give largely ethers as products, and the ethers slowly react giving the 2,4-dinitrophenoxide ion.These reactions of DNF and DNC are faster than reactions with OH- in water but are much slower than those in alcohols.Quantitatively, the relative apparent nucleophilicities of hydroxide and alkoxide ion in the micelle or microemulsion droplet are similar to those in the absence of surfactant.Anionic microemulsions of sodium lauryl sulfate (NaLS) inhibit reactions, but to smaller extent than anionic micelles in water.