Sulfur trioxide sulfonation of aromatic hydrocarbons

Cerfontain, H.

doi:10.1002/recl.19851040602

Cited by 34 publications

(35 citation statements)

References 74 publications

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“…Step 3 requires a significant reorientation of the two SO 3 molecules toward the plane of the benzene ring to make a cyclic proton rearrangement possible. This mechanism differs from the proposed mechanism of Cerfontain and coworkers 13 – 16 in that it does not account for an intermediate σ-complex state. Although its presence is not ruled out, our simulations confirm previous experimental and theoretical data 12 , 24 that the stability of σ-complexes is generally low and may be discarded from the kinetic model.…”

Section: Resultscontrasting

confidence: 82%

“…We first examine if a stable σ-complex can be formed between benzene and a single SO 3 molecule, as proposed by Cerfontain and coworkers, 13 – 16 and if aromatic sulfonation is possible with only 1 SO 3 . MTD simulations are performed with one collective variable (CV), the coordination number CN CS that measures bond formation between a benzene carbon and the SO 3 sulfur.…”

Section: Resultsmentioning

confidence: 99%

“…Based on kinetic experiments on chlorobenzene and 1,4-dichlorobenzene, Cerfontain and coworkers proposed a three-step kinetic scheme for the sulfonation of arenes with SO 3 in aprotic solvents ( Scheme 1 ). 13 – 16 The first step is a reversible reaction wherein a σ-complex is formed between the arene and a SO 3 molecule. In the second step a second SO 3 reversibly binds to the first SO 3 .…”

Section: Introductionmentioning

confidence: 99%

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Aromatic sulfonation with sulfur trioxide: mechanism and kinetic model

et al. 2017

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Section: Resultscontrasting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Aromatic sulfonation with sulfur trioxide: mechanism and kinetic model

et al. 2017

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“…SO 3 may attack as a free species or attached to a carrier. The classic kinetic studies of Cerfontain , provided important insights into the mechanism of sulfonation with SO 3 and underlined the importance of the medium in the course of the sulfonation reaction. On the basis of these investigations, Cerfontain proposed the reaction sequence for the process shown in Scheme .…”

Section: Sulfonation With Sulfur Trioxidementioning

confidence: 99%

Electrophilic Aromatic Substitution: New Insights into an Old Class of Reactions

et al. 2016

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The classic SEAr mechanism of electrophilic aromatic substitution (EAS) reactions described in textbooks, monographs, and reviews comprises the obligatory formation of arenium ion intermediates (σ complexes) in a two-stage process. Our findings from several studies of EAS reactions challenge the generality of this mechanistic paradigm. This Account focuses on recent computational and experimental results for three types of EAS reactions: halogenation with molecular chlorine and bromine, nitration by mixed acid (mixture of nitric and sulfuric acids), and sulfonation with SO3. Our combined computational and experimental investigation of the chlorination of anisole with molecular chlorine in CCl4 found that addition-elimination pathways compete with the direct substitution processes. Detailed NMR investigation of the course of experimental anisole chlorination at varying temperatures revealed the formation of addition byproducts. Moreover, in the absence of Lewis acid catalysis, the direct halogenation processes do not involve arenium ion intermediates but instead proceed via concerted single transition states. We also obtained analogous results for the chlorination and bromination of several arenes in nonpolar solvents. We explored by theoretical computations and experimental spectroscopic studies the classic reaction of benzene nitration by mixed acid. The structure of the first intermediate in this process has been a subject of contradicting views. We have reported clear experimental UV/vis spectroscopic evidence for the formation of the first intermediate in this reaction. Our broader theoretical modeling of the process considers the effects of the medium as a bulk solvent but also the specific interactions of a H2SO4 solvent molecule with intermediates and transition states along the reaction path. In harmony with the obtained spectroscopic data, our computational results reveal that the structure of the initial π complex precludes the possibility of electronic charge transfer from the benzene π system to the nitronium unit. In contrast to usual interpretations, our computational results provide compelling evidence that in nonpolar, noncomplexing media and in the absence of catalysts, the mechanism of aromatic sulfonation with sulfur trioxide is concerted and does not involve the conventional σ-complex (Wheland) intermediates. Stable under such conditions, (SO3)2 dimers react with benzene much more readily than monomeric sulfur trioxide. In polar (complexing) media, the reaction follows the classic two-stage SEAr mechanism. Still, the rate-controlling transition state involves two SO3 molecules. The reactivity and regioselectivity in EAS reactions that follow the classic mechanistic scheme are quantified using a theoretically evaluated quantity, the electrophile affinity (Eα), which measures the stabilization energy associated with the formation of arenium ions. Examples of applications are provided.

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“…The structure of "Wheland-type intermediate" kinetic study of a couple of substituted aromatic molecules in various aprotic solvents, that the Wheland-type intermediate (Figure 1) could survive long enough to react with a second SO 3 to form another Wheland intermediate of 2:1 composition (ArH + S 2 O 6 -) leading to the formation of arenepyrosulfonic acid (ArS 2 O 6 H) [35][36][37]. However, Morley et al suggested a more detailed but quite different pathway based on various molecular modeling methods and in situ 1 H NMR spectroscopy of the sulfonation of toluene.…”

Section: Introductionmentioning

confidence: 99%

Sulfonation mechanisms of aromatic polymers for PEMFC applications

Yan

Yue

2021

Fuel Cells

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The sulfonated aromatic polymers are competitive proton conducting materials for proton exchange membrane fuel cells because of their relatively low costs and adequate performances compared with the perfluorinated sulfonic acid ionomers. These polymeric materials can be economically synthesized by the sulfonation of existing aromatic polymers; however, the inadequate sulfonation degree has prevented the further optimization of their overall performances. In order to improve the overall performances of sulfonated aromatic polymeric proton conducting materials, the sulfonation mechanisms of typical aromatic polymers, including bisphenol A type polysulfone (BPA-PSF), 4,4'-biphenol type polysulfone (44BP-PSF), poly(ether ether ketone) (PEEK), and poly(ether sulfone) (PES), are studied in terms of transition states and activation energies using density functional theory calculations with satisfactory results. It is concluded that the sulfonations are favored at the ortho-position of direct arylene-arylene linkage and ether bond linkage, but retarded by the bulky sulfonyl linkage, dimethyl methylene linkage, and carbonyl linkage. It is also concluded that the solvation effect from polar solvent reduces the activation barrier more efficiently than that from nonpolar solvent.

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Sulfur trioxide sulfonation of aromatic hydrocarbons

Cited by 34 publications

References 74 publications

Aromatic sulfonation with sulfur trioxide: mechanism and kinetic model

Aromatic sulfonation with sulfur trioxide: mechanism and kinetic model

Electrophilic Aromatic Substitution: New Insights into an Old Class of Reactions

Sulfonation mechanisms of aromatic polymers for PEMFC applications

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