Temperature effects upon aqueous micellar-assisted decarboxylation of 6-nitrobenzisoxazole-3-carboxylate and its 5-methyl derivative.
An investigation of temperature effects upon first-order rate constants in the micellar pseudophase for decarboxylation of 6-nitrobenzisoxazole-3-carboxylate (6-NBIC) and its 5-methyl derivative (6-NBIC-5-Me) was carried out. Surfactants used were cationic cetyltrialkylammonium bromide with alkyl = methyl (CTABr), ethyl (CTEABr), n-propyl (CTPABr), and n-butyl (CTBABr). The investigation shows that micelles speed up reactions by decreasing enthalpies of activation. Increase in head group bulk further speeds reactions still by a small decrease in the enthalpies, for both substrates. Values of DeltaH# and DeltaS# for 6-NBIC in the various surfactants give linear isokinetic plot, with CTBABr as outlier.
Effects of Amine Oxide Surfactants on Reactions of Bromide and Hydroxide Ions with Methylnaphthalene-2-Sulfonate.
The SN2 reaction of Br- with methylnaphthalene-2-sulfonate (MeONs) in water is accelerated by micelles of tetradecyldialkyl amine oxide (alkyl = methyl, n-propyl) and rates increase sharply in HBr due to increased binding of Br- to the protonated amine oxide. Second-order rate constants at the micellar surface are similar to those at surfaces of trialkylammonium and sulfobetaine micelles. The reaction of OH- with MeONs is weakly inhibited by amine oxide micelles, showing that dispersive, as well as coulombic and charge-dipole, forces play a major role in the association of ions with surfaces of micellar aggregates. Copyright 1999 Academic Press.
Chemistry of interfacial organic processes
This article summarizes our work with (1) reaction mechanisms at hydrocarbon-water interfaces, (2) the use of emulsifying agents in synthetically useful interfacial systems, (3) the conformations of bolaform electrolytes at air-water interfaces, (4) the analysis of reaction kinetics at micellar surfaces, (5) the rotamer population at a micelle interface, (6) mechanisms of fast proton transfers at a micelle interface, (7) the properties of organic and enzymatic reactions occurring inside water pools, (8) the design of a polymeric reducing agent and (9) the pyrochromatography of structurally related steroids using hot quartz and platinum surfaces in the absence