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; Spreti, Nicoletta; Profio, Pietro Di

doi:10.1016/j.jcis.2005.11.050

Cited by 5 publications

(9 citation statements)

References 29 publications

(46 reference statements)

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“…The latter is defined by the concentration of free surfactant ions (∼cmc) and free counterions (α(c − cmc)). As generally found for spherical micelles, 20,28 the χ −1 values of DTAB, DTAC, and DTAMs are comparable but somewhat smaller than χ Debye −1 (Table 4). The large difference for DTATf is unusual and will be discussed below.…”

Section: ■ Resultssupporting

confidence: 76%

“…28 For all studied surfactants, the Z ib values were very similar (∼10) and clearly larger than zero, in line with previous findings for DTAB and DTAC at 25 °C. 20,27 This is surprising because for Cl − , Br − , 28 and Ms −53 Z ib = 0 was found (i.e., the interaction strength of these anions is not sufficient to freeze the reorientation of water molecules in their hydration shells). A value of Z ib = 0 is also likely for triflate because this anion is known for its low hydration number.…”

Section: ■ Resultsmentioning

confidence: 99%

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Dielectric Relaxation Spectroscopy Shows a Sparingly Hydrated Interface and Low Counterion Mobility in Triflate Micelles

et al. 2013

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The properties of ionic micelles are affected by the nature of the counterion. Specific ion effects can be dramatic, inducing even shape and phase changes in micellar solutions, transitions apparently related to micellar hydration and counterion binding at the micellar interface. Thus, determining the hydration and dynamics of ions in micellar systems capable of undergoing such transitions is a crucial step in understanding shape and phase changes. For cationic micelles, such transitions are common with large organic anions as counterions. Interestingly, however, phase separation also occurs for dodecyltrimethylammonium triflate (DTATf) micelles in the presence of sodium triflate (NaTf). Specific ion effects for micellar solutions of dodecyltrimethylammonium chloride (DTAC), bromide (DTAB), methanesulfonate (DTAMs), and triflate (DTATf) were studied with dielectric relaxation spectroscopy (DRS), a technique capable of monitoring hydration and counterion dynamics of micellar aggregates. In comparison to DTAB, DTAC, and DTAMs, DTATf micelles were found to be considerably less hydrated and showed reduced counterion mobility at the micellar interface. The obtained DTATf and DTAMs data support the reported central role of the anion's -CF3 moiety with respect to the properties of DTATf micelles. The reduced hydration observed for DTATf micelles was rationalized in terms of the higher packing of this surfactant compared to that of other DTA-based systems. The decreased mobility of Tf(-) anions condensed at the DTATf interface strongly suggests the insertion of Tf(-) in the micellar interface, which is apparently driven by the strong hydrophobicity of -CF3.

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Section: ■ Resultssupporting

confidence: 76%

Section: ■ Resultsmentioning

confidence: 99%

Dielectric Relaxation Spectroscopy Shows a Sparingly Hydrated Interface and Low Counterion Mobility in Triflate Micelles

et al. 2013

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“…Brinchi et al [41] studied the decarboxylation of anionic 6-nitrobenzisoxazole-3-carboxylate (6-NBIC) and its 5-methyl derivative (6-NBIC-5-Me) in the presence of a series of several cationic cetyltrialkylammonium bromide surfactants including CTAB, CTEAB, CTPAB, and CTBAB, Figure 5.…”

Section: Decomposition Reactionsmentioning

confidence: 99%

“…It was also observed that the reaction rate increases with the surfactant concentration when the surfactant concentration is low and then decreases with further increase in the surfactant concentration. It seems that with increase in the surfactant concentration, different interactions are involved between substrate and surfactants 8 Journal of Chemistry Figure 5: Decarboxylation of substrates 6-NBIC and 6-NBIC-5-Me [41]. molecules in these two cases.…”

Section: Decomposition Reactionsmentioning

confidence: 99%

Effects of Surfactants on the Rate of Chemical Reactions

Samiey

Cheng

2014

Journal of Chemistry

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Surfactants are self-assembled compounds that depend on their structure and electric charge can interact as monomer or micelle with other compounds (substrates). These interactions which may catalyze or inhibit the reaction rates are studied with pseudophase, cooperativity, and stoichiometric (classical) models. In this review, we discuss applying these models to study surfactant-substrate interactions and their effects on Diels-Alder, redox, photochemical, decomposition, enzymatic, isomerization, ligand exchange, radical, and nucleophilic reactions.

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“…N agg diminui modestamente com a temperatura tanto para DTAB (Malliaris et al 1985;Mata et al 2005), quanto para DTAC (Malliaris et al 1985). x 10 -5 s -1 , de uma extrapolação exponencial de dados de k w a diferentes temperaturas (Brinchi et al 2006). Equação 35…”

Section: Simulação De Dinâmica Molecular (Molecular Dynamics Md)unclassified

Trifluorometilsulfonato como contra-íon de micelas catiônicas

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Temperature effects upon aqueous micellar-assisted decarboxylation of 6-nitrobenzisoxazole-3-carboxylate and its 5-methyl derivative

Cited by 5 publications

References 29 publications

Dielectric Relaxation Spectroscopy Shows a Sparingly Hydrated Interface and Low Counterion Mobility in Triflate Micelles

Dielectric Relaxation Spectroscopy Shows a Sparingly Hydrated Interface and Low Counterion Mobility in Triflate Micelles

Effects of Surfactants on the Rate of Chemical Reactions

Trifluorometilsulfonato como contra-íon de micelas catiônicas

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