Reagent Concentration and Microenvironment as Key Factors in Micellar Catalysis in Reactions of Hydroperoxide and Hypobromite Anions with Acyl Substrates

Kinetic regularities of nucleophilic substitution reactions at electron-deficient centers (phosphorus and sulfur) in organized microheterogeneous systems based on cationic surfactants and α-nucleophiles―hypobromite and hydroperoxide ions―have been analyzed in terms of the pseudophase distribution model. The contribution of the concentration effects of substrates (4-nitrophenyl esters of phosphonic, phosphorous, and toluenesulfonic acids) and nucleophiles (HOO– and BrO– anions) has been quantitatively evaluated on the basis of reactant binding constants. The contribution of the microenvironment has been assessed using the second-order reaction rate constants in water (kw2,HOO–, kw2BrO–, M–1 s–1) and in the micellar pseudophase (km2,HOO–, km2,BrO–, M–1 s–1). The significance of the “trivial” concentration effect in micellar catalysis has been established.