OXIDATIONS OF ORGANIC SULFIDES IN AQUEOUS SULFOBETAINE MICELLES

Zwitterionic micelles of N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SB3-14) inhibit oxidations of 3-chloroethyl phenyl sulfide (PhSCH(2)CH(2)Cl) and 1-methoxy-4(methylthio)benzene (ArSMe) by peroxymonosulfate ion (HSO5-) and the periodate ion oxidation of ArSMe, but there are slow residual reactions of micellar-bound substrates. Measurements of the critical micelle concentration and conductance of solutions of NaIO4 and SB3-14 show that IO4- binds to sulfobetaine micelles and changes in the H-1 chemical shifts of SB3-14 confirm this assumption. The estimated second order rate constants for reaction of IO; and ArSMe are similar in SB3-14 and cationic micelles but lower than that in water by a factor of ca. 10(3), These low rate constants are due to charge-charge interactions in the transition states of reactions at micellar surfaces, Similar results were observed with HSO;. These rate constants at surfaces of zwitterionic and cationic micelles are much lower than at surfaces of anionic micelles. (C) 1995 Academic Press, Inc.