Sulfuric acid reaction with aryl sulfonic acids

The sulfonation of aromatic compounds occurs readily in ionic liquids, with the simplest case being the direct sulfonation of aromatic compounds with sulfur trioxide to give the aryl sulfonic acid [113]. Ionic liquids such as triflate or triflimide ionic liquids were found to enhance the reaction rate. In the reaction of chloro-sulfuric acid with aromatic compounds, the reaction in the ionic liquid gave a... 

Sulfate monoesters can react by dissociative paths, and this is the favored path. Whether such reactions are concerted or involve a very short-lived sulfur trioxide intermediate has been the subject of debate. ° Benkovic and Benkovic reported evidence suggesting that the nucleophile is present (though there is little bond formation) in the transition state for the reaction of amines with p-nitrophenyl sulfate. Alkyl esters of sulfuric or sulfonic acids normally react with C-0 cleavage only when this is disfavored, as in aryl esters, does one see S-0 cleavage. Sulfate diester... 

Nucleophilic reactivity of exocyclic sulfur appears in acidic medium. 2-Aryl thiazolyl sulfones are obtained from the corresponding sulfides by oxidation with H2Oz in HOAc at 100°C (272). The same oxidation takes place with alkyl sulfides (203. 214, 273-275) and dithiazolylsulfides (129). However, the same reaction with 2-benzylthio derivatives gives benzylal-cohol and the related A-4-thiazoline-2-thione (169). 

The sulfonation of triphenyl phosphine with fuming sulfuric acid can give three possible products monosulfonated triphenylphosphine (TPPMS), disulfonated triphenylphosphine (TPPDS), and TPPTS 1, depending on the reaction conditions (Figure 9). Using this method many sulfonated aryl phophines have been prepared (2b,... 

Sulfonation with Sulfuric Acid and Sulfur Triozide. Various mechanisms for the reaction of aromatic hydrocarbons or aryl halides with sulfuric acid or with sulfur trioxide have been proposed. Since.the reaction is heterogeneous, it is not favorable for experimental study. Solvents that dissolve sulfuric acid or sulfur trioxide form addition compounds with the reagent hence any conclusion drawn from a homogene ous sulfonation might not be applicable to the ordinary sulfonation. One possibility is that an electrophilic reagent such as sulfur trioxide with its relatively positive sulfur atom or an ion such as HOaS" " in the case of sulfuric acid attacks the negative center of the polarized form of the hydrocarbon, as illustrated for benzene. 

In the sulfonation of the less reactive aromatic hydrocarbons or aryl halides, it is desirable to use 5-20% oleum, which brings about reaction at a convenient rate at moderate temperatures (0-50°) furthermore, if oleum is used, less sulfuric acid remains at the completion of the reaction to interfere with the isolation of the product. In the preparation of salts, however, this factor is of less significance. Although sulfur tiioxide is even more active than oleum, it can be used to advantage only occasionally because it favors the formation of a sulfone. The formation of by-products is decreased by use of a solvent a suitable solution can be prepared by passing the gaseous material, obtained by warming 60% oleum, into cold ethylene dichloride. 

Sulfonates With sulfonates, the sulfur atom is directly attached to the carbon atom of the alkyl group and this gives the molecule stability against hydrolysis, when compared with the sulfates (whereby the sulfur atom is indirectly linked to the carbon of the hydrophobe via an oxygen atom). The alkyl aryl sulfonates are the most common type of these surfactants (for example, sodium alkyl benzene sulfonate) and these are usually prepared by reaction of sulfuric acid with alkyl aryl hydrocarbons, e.g., dodecyl benzene. A special... 

Sultones are the internal esters of hydroxy sulfonic acids and sulfur analogs of lactones. The biological activities of sultones are concerned with toxicological, skin sensitization, and antiviral properties [13]. In 2009, Majumdar developed a Pd(PPh3)4-catalyzed intramolecular C-H arylation reaction of benzenesulfonic acid 2-bromophenyl esters to afford polycyclic sultones, which are generally synthesized by elimination of the corresponding hydroxyl sulfonic acid derivatives, in up to 90% yield (Scheme 3.3, path a) [14]. TBAB was found to be critical in this reaction, and no reaction occurred in the absence of this additive. An electrophilic palladation mechanism was proposed for this transformation. 

Sultones are the internal esters of hydroxy sulfonic acids and are the sulfur analogs of lactones. Sultones are demanded scaffolds in medicinal chemistry research. Biological studies on sultones are mainly concerned with their toxicological, skin sensitization, and antiviral activities [20]. Sultones are synthetically useful heterocycles which can react with a variety of compounds to introduce the alkylsulfonic acid function and therefore used as sulfoalkylating agents [21]. There have been several new developments for the synthesis of sultones which have also been applied in the total synthesis of natural products. In recent years, the palladium-catalyzed direct arylation of several aromatics via a C-H bond activation using aryl halides has led to successes. An intramolecular version of this reaction has allowed the synthesis of several biaryls via the formation of five- to seven-membered rings. Thus, the sultones should be synthesized by C-H activation via two pathways (Scheme 4.14). 

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