- The Hammett equation and micellar effects on SN2 reactions of methyl benzenesulfonates - The role of micellar polarity
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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.
- Brinchi, Lucia,Di Profio, Pietro,Germani, Raimondo,Savelli, Gianfranco,Spreti, Nicoletta,Bunton, Clifford A.
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- Methyl Transfers. 8. The Marcus Equation and Transfer between Arenesulfonates
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Using a 35S label, rates of identity methyl-transfer reactions XC6H4*SO3(1-) + CH3O3SC6H4X -> XC6H4*SO3CH3 + XC6H4SO3(1-) in sulfolane have been measured.For all five cases, these identity rates fit the Hammett equation with the rather large ρ of +0.6.Rates and equilibria for XC6H5SO3Me + 3,4-Cl2C6H3SO3(1-) have been measured.The fit to the Marcus equation using averages of the experimental identity rates for the intrinsic rate is perfect, within experimental error.The absolute values of ρ for the forward and reverse reactions differ by an amount quantitatively consistent with the nonzero identity reaction ρ.The significance of the identity reaction ρ > 0 is discussed.
- Lewis, Edward S.,Hu, Daniel D.
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- Perchlorate Esters. Part 3. Correlation of the Rates of Reaction of Arenesulphonate Ions with Methyl Perchlorate in Acetonitrile
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Second-order rate coefficients for the reactions of acetonitrile solutions of tetra-n-butylammonium benzensulphonate and seven meta- and para-substituted derivatives with methyl perchlorate, at 0.3 deg C lead to a Hammet ρ value (-1.10 +/- 0.04) essentially identical to those previously reported for reactions with other powerful methylating agents.When silver ion is substituted for tetra-n-butylammonium ion, the second-oreder rate coefficients become concetration dependent and the fall of with increasing salt concetration can be rationalised on the basis of only free anions being reactive.The calculated degrees of dissociation are applied tothe previously studied silver0ion assisted reaction of silver toluene-p-sulphonate with methyl iodide.
- Kevill, Dennis N.,Lin, Gloria Meichia L.,Bahari, Mohd S.
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- Copper-Catalyzed Multicomponent Reaction of DABCO·(SO2)2, Alcohols, and Aryl Diazoniums for the Synthesis of Sulfonic Esters
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A Cu-catalyzed multicomponent cascade reaction of DABCO·(SO2)2 (DABSO), alcohol, and aryl diazonium tetrafluoroborate was developed which afforded sulfonic esters in moderate to good chemical yields. In this reaction, the SO2 surrogate DABSO was used for the first time in the synthesis of sulfonic aliphatic esters. This multicomponent reaction was carried out under mild conditions and tolerated a wide range of substrates, which provides a new and efficient strategy for the synthesis of sulfonic esters.
- Wang, Yang,Deng, Lingling,Deng, Yu,Han, Jianlin
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p. 4674 - 4680
(2018/04/26)
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- The SN3-SN2 spectrum. Rate constants and product selectivities for solvolyses of benzenesulfonyl chlorides in aqueous alcohols
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Rate constants for a wide range of binary aqueous mixtures and product selectivities (S) in ethanol - Water (EW) and methanol-water (MW) mixtures, are reported at 25 °C for solvolyses of benzenesulfonyl chloride and the 4-chloro - Derivative. S is defined as follows using molar concentrations: S =([ester product]/[acid product]) × ([water solvent]/[alcohol solvent]). Additional selectivity data are reported for solvolyses of 4-Z-substituted sulfonyl chlorides (Z - OMe, Me, H, Cl and NO2) in 2, 2, 2-trifluoroethanol-water. To explain these results and previously published data on kinetic solvent isotope effects (KSIEs) and on other solvolyses of 4-nitro and 4-methoxybenzenesulfonyl chloride, a mechanistic spectrum involving a change from third order to second order is proposed. The molecularity of these reactions is discussed, along with new term 'SN3-SN2 spectrum' and its connection with the better established term 'S N2-SN1 spectrum'. Copyright
- Bentley, T. William,Jones, Robert O,Kang, Dae Ho,Koo, Sun
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scheme or table
p. 799 - 806
(2010/06/16)
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- The Hammett equation applied to the nucleophilic displacement of ions and ion pairs on substituted benzenesulphonates
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Nucleophilic substitution on meta- and para-substituted methyl benzenesulphonates was studied with two chloride salts with different structures: NBu4Cl or KCl-Kryptofix 2,2,2. Treating the results with the Acree equation shows that the reaction proceeds by two reaction paths, one involving the chloride ion and the other, slower one, involving the ion pairs. Treating the results with the Hammett equation gives consistent data, and shows that ρ is positive and nearly the same for the two reaction paths (ρ ≈ +2). The reactivity of methyl p-nitrobenzenesulphonate was compared with that of the corresponding ethyl derivative, and it is shown that the methyl derivative reacts faster than the ethyl derivative in both paths. The results are interpreted based on the assumption that in both paths a negative charge is developed on the leaving group in the transition state, and that the activated complex is linear. Copyright
- Alunni, Sergio,Pica, Monica,Reichenbach, Gustavo
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p. 265 - 270
(2007/10/03)
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- Bimolecular Nucleophilic Substitution (SN2) Reactions of Neopentyl Arenesulfonates with Anilines and Benzylamines in Methanol
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Bimolecular nucleophilic substitution (SN2) reactions of neopentyl arenesulfonates with anilines and benzylamines in methanol at 55.0 deg C are reported.The tightness of the transition state (TS) is similar to that for other typical SN2 processes at a primary alkyl carbon centre based on the magnitude of the cross-interaction constant ρxz (0.30) between the substituents in the nucleophile (X) and leaving group (Z).The TS variation is in accord with that predicted by the potential energy surface diagram, which in turn is consistent with the positive sign of ρxz; a later TS is obtained with a weaker nucleophile and nucleofuge.Taft's polar substituent constant, ?*, for the trimethylsilyl group is estimated to be -0.48 by using a factor of 1.875 for the fall-off of ?* from the tert-butyl to the neopentyl group and extrapolating from the experimental Taft plot.
- Koh, Han Joong,Lee, Hai Whang,Lee, Ikchoon
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p. 253 - 258
(2007/10/02)
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- REACTION OF METHYL METHANESULFONATE WITH SULFUR TRIOXIDE AND CHLOROBENZENE
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The reactivity of methyl methanesulfonate in reaction with sulfur trioxide is lower than that of methyl arenesulfonates.Methyl methanesulfonate becomes exhausted when the ester and sulfur trioxide are in ratio of 1.85:1, while methyl p-toluenesulfonate becomes exhausted in ratio of 1:1 (25 deg C, 1 h).If an equimolar amount of chlorobenzene is added to the mixture of methyl methanesulfonate and sulfur trioxide in ratio of 1:1, the main reaction path is solvolysis of the pyrosulfonates to methanesulfonic acid and methylsulfuric acid and not the formation of sulfones, as in case of arenesulfonic esters.
- Andrashchuk, N. P.,Shapiro, Yu. E.,Timoshenko, G. N.,Moskvichev, Yu. A.,Mironov, G. S.,et al.
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p. 1144 - 1148
(2007/10/02)
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- CORRELATION OF THE RATES OF REACTION OF ARENESULFONATE IONS WITH THE TRIMETHYLOXONIUM ION IN ACETONITRILE
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The kinetics of the reactions between trimethyloxonium hexafluorophosphate and a series of tetra-n-butylammonium arenesulfonates have been studied in acetonitrile at -23.4 deg C.With the oxonium salt concentration at about 0.01 M, two series of runs were carried out; Hammett plots of the second-order rate coefficients led to ρ values of -1.18 +/- 0.04 for 0.04 M arenesulfonate salt and -1.07 +/- 0.02 for 0.16 M arenesulfonate salt.Solvolysis kinetics for the trimethyloxonium ion in acetonitrile are also reported.
- Kevill, Dennis N.,Lin, Gloria Meichia L.,Wang, An
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p. 715 - 717
(2007/10/02)
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