NMR study of the location of bromide ion and methyl naphthalene-2-sulfonate in cationic micelles: relation to reactivity

Bacaloglu, R.; Bunton, Clifford A.; Cerichelli, Giorgio; Ortega, Francisco

doi:10.1021/j100341a060

Cited by 91 publications

(63 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Figure 3 shows the solid single-pluse 13 C MAS NMR spectra of crystalline CTMAB, CTMAB/montmorillonite hybrids and 13 C NMR spectrum of CTMAB in solution. The liquid NMR spectrum of CTMAB was cited from literature [19], which was recorded in CDCl 3 with a 0.1M concentration of CTMAB at 25 o C. The chemical shift δ (ppm) and their assignment are shown in Table 2.…”

Section: C Sp Mas Nmrmentioning

confidence: 99%

Characterization of organic phases in the interlayer of montmorillonite using FTIR and 13C NMR

Zhu

et al. 2005

Journal of Colloid and Interface Science

178

137

View full text Add to dashboard Cite

show abstract

Section: C Sp Mas Nmrmentioning

confidence: 99%

Characterization of organic phases in the interlayer of montmorillonite using FTIR and 13C NMR

Zhu

et al. 2005

Journal of Colloid and Interface Science

178

137

View full text Add to dashboard Cite

show abstract

“…On the basis of electrostatic considerations, one would expect some incorporation of 4NBD ions into the SDS micellar aggregates because 4NBD ions bear a positive charge but are somewhat hydrophobic, while the surface of SDS micelles is negatively charged. Because arenediazonium ions have been proved to be very sensitive to their environment H-NMR spectroscopy, which allows aromatic rings to be located by the upfield shift induced by the ring current (ring-current effect) on the signals of neighboring H-atoms of the surfactant, an effect which depends upon the distance between the ring and the corresponding H-atoms [42]. The method has already been employed to locate diazonium ions [43] and a number of compounds containing benzene rings in micellar aggregates [44].…”

Section: à5mentioning

confidence: 99%

Effects of Micellar Aggregates on the Kinetics and Mechanism of the Reaction between 4‐Nitrobenzenediazonium Ions and Some Amino Acids

Fernández-Alonso

Bravo‐Díaz

2007

Helvetica Chimica Acta

View full text Add to dashboard Cite

We have explored the kinetics and mechanism of the reaction between 4-nitrobenzenediazonium ions (4NBD), and the hydrophilic amino acids (AA) glycine and serine in the presence and absence of sodium dodecyl sulfate (SDS) micellar aggregates by means of UV/VIS spectroscopy. The observed rate constants k obs were obtained by monitoring the disappearance of 4NBD with time at a suitable wavelength under pseudo-first-order conditions. In aqueous acid (buffer-controlled) solution, in the absence of SDS, the dependence of k obs on [AA] was obtained from the linear relationship found between the experimental rate constant and [AA]. At a fixed amino acid concentration, k obs values show an inverse dependence on acidity in the range of pH 5 -6, suggesting that the reaction takes place through the nonprotonated amino group of the amino acid. All kinetic evidence is consistent with an irreversible bimolecular reaction with k ¼ 2390 AE 16 and 376 AE 7 m À1 s À1 for glycine and serine, respectively. Addition of SDS inhibits the reaction because of the micellar-induced separation of reactants originated by the electrical barrier imposed by the SDS micelles; k obs values are depressed by factors of 10 (glycine) and 6 (serine) on going from [SDS] ¼ 0 up to [SDS] ¼ 0.05m. The hypothesis of a micellar-induced separation of the reactants was confirmed by 1 H-NMR spectroscopy, which was employed to investigate the location of 4NBD in the micellar aggregate: the results showed that the aromatic ring of the arenediazonium ion is predominantly located in the vicinity of the C(b) atom of the surfactant chain, and hence the reactive ÀN þ 2 group is located in the Stern layer of the micellar aggregate. The kinetic results can be quantitatively interpreted in terms of the pseudophase kinetic model, allowing estimations of the association constant of 4NBD to the SDS micelles.

show abstract

“…A freqüência da banda amida I dos tensoativos após a c. , BACALOGLU et al, 1989BACALOGLU et al, 1991;CHEVALIER et al, 1985;LEVY et al, 1974;UZU et al, 1989;WALDERHAUG et al, 1984 …”

Section: Estudo Da Agregação Por IVunclassified

Síntese e propriedades de soluções de tensoativos catiônicos derivados de (3-dimetilaminopropil)amidas de ácidos carboxílicos

Pires¹

View full text Add to dashboard Cite

sua orientação e pelos caminhos abertos; ao Prof. Watson Loh e à Priscilla (IQ-UNICAMP), pelo auxílio nas medidas de calorimetria; à minha família, pelo amor, incentivo e apoio constantes; à Katia, por todo o apoio dado nestes últimos anos; aos colegas: Reinaldo, Susana, Cesar, Érika, Naiara, Ricardo, Paula, Priscilla, Shirley, Márcia, Guilherme, Ana Luiza, Euzita e Miriam; com quem trabalhei e/ou trabalho nestes muitos anos de IQ, pela amizade, compreensão e apoio; à Olga pelo auxílio com o português; aos meus amigos Metil, Jair, Harrald e Gesivaldo; a todos os funcionários do IQ-USP e da Biblioteca que durante todos estes anos me deram o suporte necessário para que esta tese pudesse ter sido elaborada; e ao CNPq, Capes, Finep e Fapesp, pelo auxílio financeiro proporcionado ao nosso laboratório e ao IQ-USP, sem o que seria impossível a realização deste trabalho. LEMBRETE (Carlos Drummond de Andrade) Se procurar bem, você acaba encontrando não a explicação (duvidosa) da vida, mas a poesia (inexplicável) da vida.Dedico esta Tese a três pessoas muito especiais em minha vida: minha esposa Olga e meus filhos Samuel e Lis; as maiores fontes de felicidade nessa minha passagem pela Terra... i ÍNDICE GERAL ÍNDICE DE FIGURASFigura 1.1 Efeito da adsorção de tensoativos na interface de uma gota de água sobre a superfície de uma substância lipofílica: (a) na ausência de tensoativo e (b) após a adição do mesmo (ATWOOD et al., 1983) 6 Figura 1.2 Representação esquemática de uma micela aquosa de um tensoativo catiônico (TANFORD, 1991). 7 Figura 1.3 Variação das diversas propriedades físico-químicas da solução em função da concentração do tensoativo (ELWORTHY et al., 1968). 9 Figura 1.4 Modelo de uma micela esférica de dodecil-sulfato de sódio (SDS) (GRUEN, 1985). Para simplicar o esquema, os contra-íons (Na + ) não estão mostrados. 10 Figura 1.5 Alguns modos de organização das moléculas de tensoativos para a redução das energias superficial e interfacial (MYERS, 1999 c.m.c. = concentração micelar crítica C n ABzMe 2 Cl = cloreto de benzil-(3-acilaminopropil)-dimetilamônio C n AMe 3 Cl = cloreto de (3-acilaminopropil)-trimetilamônio C n Me 2 = (3-dimetilaminopropil)amidas de ácidos carboxílicos C n 'BzMe 2 Cl = cloreto de dimetilbenzilalquilamônio C n 'Me 3 Cl = cloreto de trimetilalquilamônio COSY = "correlation spectroscopy" (RMN) D = coeficiente de difusão dn/dc = incremento do índice de refração específico do soluto E T = energia de transição intramolecular da sonda solvatocrômica f ± = coeficiente de atividade médio (ânion/cátion) FEM = força eletromotriz de uma cela reversível h = constante de Planck HATR = IV por reflectância total atenuada horizontal HETCOR = "heteronuclear correlation" (RMN) I = força iônica da solução i s = intensidade de luz espalhada J = constante de acoplamento spin-spin (RMN) k B = constante de Boltzmann K Assoc = Constante de associação de um substrato (por ex. sondas de polaridade) à micela. Os tensoativos são moléculas anfifílicas, isto é, possuem, na sua estrutura, duas regiões de polarid...

show abstract

NMR study of the location of bromide ion and methyl naphthalene-2-sulfonate in cationic micelles: relation to reactivity

Cited by 91 publications

References 0 publications

Characterization of organic phases in the interlayer of montmorillonite using FTIR and 13C NMR

Characterization of organic phases in the interlayer of montmorillonite using FTIR and 13C NMR

Effects of Micellar Aggregates on the Kinetics and Mechanism of the Reaction between 4‐Nitrobenzenediazonium Ions and Some Amino Acids

Síntese e propriedades de soluções de tensoativos catiônicos derivados de (3-dimetilaminopropil)amidas de ácidos carboxílicos

Contact Info

Product

Resources

About