The Pseudophase Model of Micellar Catalysis. Addition of Cyanide Ion to N-Alkylpyridinium Ions

Article abstract of DOI:10.1021/ja00531a036

Cationic micelles speed addition of cyanide ion to the 4 position of N-alkyl-3-carbamoylpyridinium bromide (alkyl = n-C12H25, n-C14H29, n-C16H33).At high concentration of cetyltrimethylammonium cyanide the reaction rates become almost independent of as substrate binding appraches completion.The rates of these reactions in 0.005 M CN^- go through maxima with increasing concentration of cetyltrimethylammonium bromide .The rate-surfactant profiles in both surfactants fit a pseudophase model of micellar catalysis.Using measured binding of the substrates to micelles of CTABr, the second-order rate constants in the micellar pseudophase are almost the same as that in water.Thus, the entire rate enhancement is due to concentration of reactants in the micellar pseudophase.