Sulfonation and Sulfonylation

Sulfonation of aromatic compounds is generally carried out with sulfuric acid, halosulfuric acids, or sulfur trioxide as reagent with or without solvent.458,459 Friedel-Crafts catalysts such as aluminum chloride and boron trifluoride are effective catalysts in certain sulfonations with sulfuric acid and chlorosulfuric acid. 

Chlorosulfuric acid (HSO3CI) reacts with aromatic hydrocarbons to give sulfonic acids, sulfonyl chlorides, and sulfones, with the relative yields depending on the reaction conditions. The reaction with benzene with an equimolar amount of 

Studying the formylation of alkylbenzenes in HS03F-SbF5, Tanaka et al436 have observed both formylation and sulfonation. However, in the presence of HSO3F, that is at low acidity level, only sulfonyl compounds were obtained [Eq. (5.167)], whereas increasing acidity (with added SbF5) resulted in the formation of products of formylation. 

Herlem et al463 have observed that asphaltene is dissolved in fluorosulfuric acid and the process is accompanied by strong redox reactions (SO2 and HF evolution). The products are mainly functionalized by SO3H groups, but SO2F groups were also detected by XPS. Indeed, model studies with benzene showed the formation of benzenesulfonic acid, diphenylsulfone, and benzenesulfonyl fluoride. For alkylbenzenes, sulfonation was not accompanied by cracking of the alkyl chain. 

Nafion-H has also been used as sulfonation catalyst.464 When oleum and long-chain alkylbenzenes were separated from each other by a Nafion-H membrane, the membrane transported the sulfonating agent into the alkylbenzene at a rate convenient for dissipating the heat of the reaction. Reported yields of sulfonation products were 34% (4h), 63% (6 h), and 86% after 22.5 h. 

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SCHEME 1. Energy levels (eV) of the HOMO and LUMO obtained from MNDO calculations of some sulfones and sulfonyl-like compounds. 

TABLE 5. Cyclopentenyl sulfones and sulfonyl lactams from (ketoethynyl)iodonium and (amido ethynyl)iodonium triflates 17 and 18 with sodium / -toluenesulfinate in dichloromethane"... 

In this work, toluene was observed to be five times more reactive than benzene. In the sulfonation of benzene, toluene and chlorobenzene by chlorosulfonic acid (just more than one molar equivalent) in dichloromethane or nitromethane, the major products were the corresponding arylsulfonic acids with only small amounts of the sulfones and sulfonyl chlorides. ... 

No reaction occurs under these conditions with esters, acid chlorides, acid anhydrides, azobenzene, sulfones, and sulfonyl chlorides. The following groups evolve hydrogen but do not undergo reduction alcohols, phenols, carboxylic acids, amides, and sulfonic acids. Aldehydes and ketones are reduced to alcohols, and N,N-dimethylamides to aldehydes. F. e. s. H. C. Brown and D. B. Big-ley, Am. Soc. 83, 486 (1961). 

Sulfonic acid hydrazides, RSO2NHNH2, are prepared by the reaction of hydraziae and sulfonyl haUdes, generally the chloride RSO2CI. Some of these have commercial appHcations as blowiag agents. As is typical of hydrazides generally, these compounds react with nitrous acid to form azides (26), which decompose thermally to the very reactive, electron-deficient nitrenes (27). The chemistry of sulfonic acid hydrazides and their azides has been reviewed (87). 

The formation of four-membered-ring sulfones and a-sulfonyl amides has also been applied to the reaction of methanesulfonyl chloride with ketene aminals and acetals (470-473). 

This sulfonate, prepared from B0CNHCH2CH2C(CH3)2CH20H and the sulfonyl chloride (Pyr, 100% yield) is cleaved by initial BOC cleavage to release the free amine after pH adjustment to 7-8. Intramolecular displacement occurs to release the sulfonate and a pyrrolidine. ... 

Nitration and sulfonation of aromatic compounds probably occur via the formation of the nitryl and sulfonyl cations ... 

TABLE 9. Bond energies in sulfoxides and sulfones, and enthalpies of formation of sulfinyl and sulfonyl radicals... 

TABLE 6. Sulfones from unsaturated systems and sulfonyl halides R S02X by radical routes... 

TABLE 9. Sulfones R S02X from different C-nucleophiles and sulfonyl halides... 

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