Oxidations of Organic Sulfides in Aqueous Sulfobetaine Micelles

摘要

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 Na1O4 and SB3-14 show that 1O4(-) binds to sulfobetaine micelles and changes in the 1H chemical shifts of SB3-14 confirm this assumption. The estimated second order rate constants for reaction of 1O4(-) and ArSMe are similar in SB3-14 and cationic micelles but lower than that in water by a factor of ca. 10(exp 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 HSO5(-). These rate constants at surfaces of zwitterionic and cationic micelles are much lower than at surfaces of anionic micelles. jg p.2.