- Aromatization modulates the activity of small organic molecules as promoters for carbon-halogen bond activation
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The combination of small organic molecules and a base serves as a unique system for the activation carbon-halogen bonds in haloarenes by single electron transfer (SET). However, most of the molecules employed as promoters only allow for the activation of aryl iodides, and efficient activation of aryl bromides and chlorides under this mode is still rather challenging. Herein, we report the discovery of a structurally simple yet powerful promoter molecule, indoline, which exhibits unusually high activity in promoting the activation of haloarenes by SET. In the presence of t-BuOK and a trace amount of oxygen, indoline promotes the formation of aryl radicals not only from aryl iodides and bromides, but also from unactivated aryl chlorides (e.g., chlorobenzene) under relatively mild conditions. Mechanistic studies reveal the molecular basis for its high activity, for which the aromatization process plays a key role in modulating the electron transfer process.
- Yang, Huan,Chu, De-Zhao,Jiao, Lei
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p. 1534 - 1539
(2018/02/14)
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- Very efficient conversion of glucose to 5-hydroxymethylfurfural in DBU-based ionic liquids with benzenesulfonate anion
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Efficient conversion of glucose to 5-hydroxymethylfurfural (HMF), an important platform molecular for fuels and chemicals, is a promising topic in green chemistry. In this work, several new DBU-based (DBU = 1,8-diazabicyclo[5. 4.0]undec-7-ene) ionic liquids (ILs) with benzene sulfonate (BS) anion were synthesized and used as the solvents for the dehydration of glucose to HMF. It was found that all the ILs were excellent solvents for the dehydration of glucose to form HMF using CrCl3 as the catalyst. The effects of various factors, such as kind of catalysts, catalyst amount, reaction time and reaction temperature, on the yields of HMF were studied systematically in the Et-DBUBS/CrCl3 catalytic system. The yield of HMF from glucose could reach 83.4% under the optimized reaction conditions, and the reasons for the high yield were investigated on the basis of control experiments. The Et-DBUBS/CrCl3 system could be reused at least five times without considerable reduction in the efficiency. Further study indicated that the catalytic system was also very efficient for transformation of fructose, inulin, and cellobiose to HMF. This journal is the Partner Organisations 2014.
- Wu, Lingqiao,Song, Jinliang,Zhang, Binbin,Zhou, Baowen,Zhou, Huacong,Fan, Honglei,Yang, Yingying,Han, Buxing
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p. 3935 - 3941
(2014/08/05)
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- Direct catalytic olefination of alcohols with sulfones
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The synthesis of terminal as well as internal olefins was achieved by the one-step olefination of alcohols with sulfones catalyzed by a ruthenium pincer complex. Furthermore performing the reaction with dimethyl sulfone under mild hydrogen pressure provides a direct route for the replacement of alcohol hydroxy groups by methyl groups in one step.
- Srimani, Dipankar,Leitus, Gregory,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 11092 - 11095
(2015/03/30)
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- Spectroscopic (FT-IR, FT-Raman and 1H and 13C NMR) and theoretical in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels study of benzenesulfonic acid and alkali metal benzenesulfonates
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The FT-IR, FT-Raman and NMR (1H and 13C) spectra of benzenesulfonic acid as well as lithium, sodium, potassium, rubidium and caesium benzenesulfonates were registered, assigned and compared. The molecular structures of ligand and alkali metal salts were discussed. On the basis of quantum mechanical calculations in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels the geometric parameters, infrared spectra, NMR spectra, the magnetic and geometric aromaticity indices for acid and alkali metal benzenesulfonates and benzoates were obtained. The effect of alkali metal ions on the electronic charge distribution of benzenesulfonic acid was studied and compared with the alkali metal benzoates and benzoic acid.
- ?widerski,Kalinowska,?wis?ocka,Wojtulewski,Lewandowski
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- On the positional reactivity order in the sulfur trioxide sulfonation of benzene, halogenobenzenes, halogenonaphthalenes, and chloroanthracenes
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The reaction of sulfur trioxide with benzene, the four halogenobenzenes, and six halogenonaphthalenes in dichloromethane as solvent, and with four chlorinated anthracenes in nitromethane as solvent, has been studied by analysis of the resulting mixture of the sulfo derivatives with 1H NMR. The sulfonation of benzene yields initially benzenesulfonic acid and subsequently the 1,3-disulfonic acid (1,3-S2). The initial sulfonation of the four halogenobenzenes yields ? 98% of the 4-S. Their subsequent sulfonation gives the 2,4-S2 and in the case of fluoro- and iodobenzene also the 2,4,6-S3. Monosulfonation of 1-fluoronaphthalene yields only the 4-S, whereas the three other 1-halogenonapthalenese yield in addition some 5-S. Further sulfonation on any of the four 1-halogenonaphthalene-4-sulfonic acids yields a mixture of the 2,4-S2 and 4,7-S2, and eventually also some 2,4,7-S3, whereas the 1-halogeno-5-sulfonic acids give the corresponding 5,7-S2. Sulfonation of 2-chloro- and 2-bromonaphthalene yields initially 85% 8-S and 15% 4-S, which are subsequently converted into the 6,8-S2 and 4,7-S2, respectively. On reaction with 1.0 mol-equiv. of SO3, 2-chloroanthracene gives the 9-S, and 9-chloroanthracene gives an 18:82 mixture of the 4-S and 10-S. Both 1,5- and 1,8-dichloroanthracene yield initially the 4-S and subsequently the 4,8-S2 and 4,5-S2, respectively.
- Cerfontain,Zou,Bakker,van de Griendt
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p. 1966 - 1971
(2007/10/02)
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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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p. 3292 - 3296
(2007/10/02)
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- Substitution Reactions of Alkanesulfonyl Derivatives: Direct Substitution vs. Elimination-Addition Mechanisms in Substitution Reactions of Alkyl α-Disulfones
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The reactions of a series of alkyl and aralkyl α-sulfones, RSO2SO2R ( R = Me, n-Bu, i-Pr, ArCH2) with a variety of nucleophiles in aqueous dioxane have been examined.Both rates of reaction and whether a given reaction takes place by an elimination-addition (sulfene intermediate) or a direct substitution (attack of nucleophile on SO2 group of α-sulphone) mechanism have been determined.The great majority of substitution reactions of alkyl α-disulfones take place via an elimination-addition mechanism (eq 3a), with formation of a sulphene from the α-disulphone being rate determining.Only when nucleophile is one, like azide ion, that is weakly basic while still being a good nucleophile is a direct substitution the preferred pathway.Even with azide the reaction pathway changes to elimination-addition when the acidity of the hydrogens on the carbon adjacent to the sulfonyl group is increased sufficiently, as in (PhCH2SO2)2.Comparison of rates of elimination of α-disulphones (R'CH2SO2)2 with rates of base-catalyzed hydrogen exchange of the corresponding trifluoromethyl sulfones R'CH2SO2CF3 indicates that formation of sulfenes from α-disulfones involves either an irreversible E1cB or a very E1cB-like E2 mechanism, a conclusion that is also supported by the observed variation of the rate of elimination of RR'CHSO2SO2R'' with changes in R and R'.Comparison of the behavior of an alkyl α-disulfone with that of the corresponding alkanesulfonyl chloride reveals that changing Y in RCH2SO2Y from RSO2 to Cl causes direct substitution to be able to compete much more effectively with elimination-addition.Kinetic studies show that this arises because, for a given nucleophile, (a) elimination-addition is 5-10 times slower for the alkanesulfonyl chloride than for the α-disulfone while (b) the rate of direct substitution is 5-10 times faster for the sulfonyl chloride.The origin of these rate differences is discussed and explained.
- Fang, Lieh-pao O.,Kice, John L.
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p. 1137 - 1145
(2007/10/02)
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- SENSITIZED PHOTO-OXIDATION OF THIOPHENOLATES A SINGLET OXYGEN REACTION
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Tetraphenylporphyrin-sensitized photo-oxidation of thiophenolates leads to the corresponding benzenesulfonates.The reaction proceeds via attack of singlet oxygen on the thiophenolate anion.A reaction mechanism is proposed.
- Jongsma, Simon J.,Cornelisse, Jan
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p. 2919 - 2922
(2007/10/02)
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