title: Effect of ethanol on micellization and on decarboxylation of 6-nitrobenzisoxazole-3-carboxylate in aqueous cationic micelles.
abstract: The effects of ethanol on the critical micellar concentration (cmc) and the rates of decarboxylation of 6-nitrobenzisoxazole-3-carboxylate (6-NBIC) have been investigated in aqueous cationic surfactants of the cetyltrialkylammonium family with bromide [CT(R)ABr], chloride [CT(R)ACl], and nitrate [CT(R)ANO3] counterions, and methyl (CTAX), n-propyl (CTPAX), and n-butyl (CTBAX) as the head group alkyl moieties. Effects upon cmc and reactivity are similar, featuring a break at the ethanol mole fraction, x(EtOH), of ca. 0.055; these effects have been related to changes in solvent structure, with formation of a clathrate at x(EtOH) = 0.055. Rate data in CTBABr were further investigated and fitting of raw kinetic data to the pseudophase model is possible up to x(EtOH) = 0.1, showing an unexpected decrease of rate constant values in the micellar pseudophase, kM', as ethanol content increases: a significant variation of micellar ionization degree could account for this kinetic effect.
authors.affiliation: Dipartimento di Chimica, Università di Perugia, Perugia, 06123, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Brinchi
authors.forename: Pietro
authors.initials: P
authors.lastname: Di Profio
authors.forename: Raimondo
authors.initials: R
authors.lastname: Germani
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Savelli
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Spreti