CHEMICAL-REACTIVITY AND BASICITY OF AMINES MODULATED BY MICELLAR SOLUTIONS

The kinetics of the reactions of several secondary aliphatic amines wi th alkyl nitrites(2-bromoethyl and 1-phenylethyl nitrites) were measur ed using the spectrophotometric technique in aqueous basic solutions a nd in the presence of sodium dodecylsulfate and tetradecyltrimethylamm onium bromide. In the case of the cationic micelles, the results were quantitatively interpreted by means of the pseudophase model, which co nsiders micelles acting as a separate phase from water. With the anion ic micelles, the results were analyzed by using the simple pseudophase ion-exchange model, in which the alkyl nitrite and the neutral form o f the amine are partitioned between the micellar and aqueous pseudopha ses, and in which the basic ionization equilibria of the amine;increas es because of the exchange between the alkylammonium ion of the amine and the micellar counterion at the micellar surface. Bimolecular rate constants for the reaction in the micellar pseudophase are always smal ler than for those in water. Characteristic features of the media and of the substrates in the reactivity behavior of amines are discussed. The binding constants of the amines (by hydrophobic or electrostatic e ffects) to the micelle are seen as related to the structure of the ami ne and the nature of the micellar surface.