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 H# and S# for 6-NBIC in the various surfactants give linear isokinetic plot, with CTBABr as outlier.
Temperature Effects upon Aqueous Micellar-assisted Decarboxylation of 6-Nitrobenzisoxazole-3-carboxylate and its 5-Methyl Derivative
BRINCHI, Lucia;GERMANI, Raimondo;GORACCI, LAURA;SAVELLI, Gianfranco;DI PROFIO, Pietro
2006
Abstract
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 H# and S# for 6-NBIC in the various surfactants give linear isokinetic plot, with CTBABr as outlier.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
