16722-51-3Relevant articles and documents
Cationic mixed micelles as reaction medium for hydrolysis reactions
Fernández, Isabel,Pérez-Juste, Jorge,Hervés, Pablo
, p. 1866 - 1874 (2015)
The influence of cationic mixed micelles composed of quartenary ammonium surfactants on hydrolysis reactions has been studied in detail. The basic hydrolysis of N-methyl-N-nitroso-p-toluene sulphonamide has been chosen as the reaction probe, while mixed micelles composed of lauryl trimethyl ammonium chloride and octadecyl trimethyl ammonium chloride with different molar ratios were studied as the reaction medium. The ion-exchange pseudophase model was used to fit the experimental results to obtain the kinetic and thermodynamic parameters of the reaction. The result show that the hydrophobic character of the mixed micelles drives the association of the substrate to them, leading to a local increase of reactant concentrations at the micellar interface and, therefore, to a catalytic effect. By tuning the molar ratio of the mixed micelles it is possible to control substrate binding affinity and thus the catalytic efficiency of the reaction medium.
Regioselectivity and the nature of the reaction mechanism in nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzenesulfonates with primary amines
Um, Ik-Hwan,Hong, Jin-Young,Kim, Jung-Joo,Chae, Ok-Mi,Bae, Sun-Kun
, p. 5180 - 5185 (2007/10/03)
Second-order rate constants have been measured for the reaction of 2,4-dinitrophenyl X-substituted benzenesulfonates with a series of primary amines. The nucleophilic substitution reaction proceeds through competitive S-O and C-O bond fission pathways. The S-O bond fission occurs dominantly for reactions with highly basic amines or with substrates having a strong electron-withdrawing group in the sulfonyl moiety. On the other hand, the C-O bond fission occurs considerably for the reactions with low basic amines or with substrates having a strong electron-donating group in the sulfonyl moiety, emphasizing that the regioselectivity is governed by both the amine basicity and the electronic effect of the sulfonyl substituent X. The apparent second-order rate constants for the S-O bond fission have resulted in a nonlinear Bronsted-type plot for the reaction of 2,4-dinitrophenyl benzenesulfonate with 10 different primary amines, suggesting that a change in the rate-determining step occurs upon changing the amine basicity. The microscopic rate constants (k1 and k2/k-1 ratio) associated with the S-O bond fission pathway support the proposed mechanism. The second-order rate constants for the S-O bond fission result in good linear Yukawa-Tsuno plots for the aminolyses of 2,4-dinitrophenyl X-substituted benzenesulfonates. However, the second-order rate constants for the C-O bond fission show no correlation with the electronic nature of the sulfonyl substituent X, indicating that the C-O bond fission proceeds through an SNAR mechanism in which the leaving group departure occurs rapidly after the rate-determining step.
The Hammett equation and micellar effects on SN2 reactions of methyl benzenesulfonates - The role of micellar polarity
Brinchi, Lucia,Di Profio, Pietro,Germani, Raimondo,Savelli, Gianfranco,Spreti, Nicoletta,Bunton, Clifford A.
, p. 3849 - 3854 (2007/10/03)
Substituent effects on the reaction of H2O, OH-, and Br- with p-substituted methyl benzenesulfonates in cationic micelles of cetyl trialkylammonium ion surfactants (n-C16H33NR3X, X = OH, Br, R = Me, Et, nPr, nBu) and in water were analyzed by using the Hammett equation. Values of p in the various media confirm that micellar interfacial regions are less polar than water and polarities decrease with increasing bulk of the surfactant head-group. Wiley-VCH Verlag GmbH, 2000.
