Sulfonation of aromatic hydrocarbons and

Stilbenes, photocyclization of, 30, 1 StiUe reaction, 50, 1 Stobbe condensation, 6, 1 Substitution reactions using organocopper reagents, 22, 2 41, 2 Sugars, synthesis by glycosylation with sulfoxides and sulfinates, 64, 2 Sulfide reduction of nitroarenes, 20, 4 Sulfonation of aromatic hydrocarbons and aryl halides, 3, 4 Swem oxidation, 39, 3 53, 1... 

C. M. Suter and A. W. Weston, Direct Sulfonation of Aromatic Hydrocarbons and Their Halogen Derivatives, Org. React. 1946, 3, 141-197. 

Direct Sulfonation of Aromatic Hydrocarbons and Their Halogen Derivatives ... 

DIRECT SULFONATION OF AROMATIC HYDROCARBONS AND THEIR HALOGEN DERIVATIVES... 

Sulfonation of aromatic hydrocarbons with sulfuric acid is cataly2ed by hydrogen fluoride or, at lower temperatures, by boron trifluoride (144). The products obtained are more uniform and considerably less sulfuric acid is needed, probably because BF forms complexes with the water formed ia the reaction, and thus prevents dilution of the sulfuric acid. 

Except for these studies of their protonation behavior, almost the only other aspect of the chemistry of sulfonic acids that has been investigated to any extent from a mechanistic point of view is the desulfonation of aromatic sulfonic acids or sulfonates. Since this subject has been well reviewed by Cerfontain (1968), and since the reaction is really more of interest as a type of electrophilic aromatic substitution than as sulfur chemistry, we shall not deal with it here. One should note that the mechanism of formation of aromatic sulfonic acids by sulfonation of aromatic hydrocarbons has also been intensively investigated, particularly by Cerfontain and his associates, and several... 

In 1948 Maxted and Walker studied the detoxification of catalyst poisons in the hydrogenation of aromatic hydrocarbons and found that the isomeric thienothiophenes 1 and 2 could be converted into the sul-fones of fully hydrogenated thienothiophenes 1 and 2, which do not poison the catalysts. This conversion is performed by brief preliminary hydrogenation and subsequent oxidation by hydrogen peroxide or per-molybdic acid. However, no data on the isolation or foe properties of these disulfones are available. It has been reported that direct oxidation of thienothiophenes 1 and 2 does not produce sulfones. 

SAFETY PROFILE A skin and severe eye irritant. Decomposes violendy at about 200°. Mixture with siolfuric acid + sulfur trioxide may explode above 150°C. When heated to decomposition it emits toxic fumes of SOx and NO. See also NITRO COMPOUNDS OF AROMATIC HYDROCARBONS and SULFONATES. 

Sulfones are often produced as by-products in the sulfonation of aromatic hydrocarbons (method 540). Aromatic hydrocarbons react with sulfonic acids less readily than with sulfuric acid. The success of the reaction depends upon the removal of the water as it is formed. An automatic water separator is used in the conversion of a refluxing mixture of benzene and sulfuric acid to diphenyl sulfone (80%). A similar technique has been employed in the preparation of unsymmetrical sulfones. 

Another type of solid superacid is based on perfluorinated resin sulfonic acids, such as the acid form of DuPont s Nafion resin, a copolymer of a perfluorinated epoxide and vinylsulfonic acid, or higher perflu-oroalkanesulfonic acids such as perfluorodecanesulfonic acid, CF3(CF2) 03H. Such solid catalysts were found to be very efficient in alkylation of aromatic hydrocarbons and other Friedel-Crafts reactions. A comprehensive review is available on the application of Nafion-H in organic catalysis. ... 

Sulfonation of aromatic hydrocarbons can be accomplished by using SO3 directly in the reaction, usually in a continuous sulfonater. This reaction is instantaneous and does not require the removal of water from the reaction. However, it gives a higher yield of sulfones and other nnwanted by-products. Chemical inhibitors can reduce sulfone production in this reaction. Interestingly, the sodium salt of the sulfonic acid, the actual hydrotrope, inhibits sulfone formation [3]. Inorganic sulfites [4] as well as acetic acid [5] can also be used. 

Sulfonic acid groups (SO3H) are both bulky and electron-withdrawing consequently once one sulfonic acid group has been introduced into the aromatic nucleus, the resultant arylsulfonic acid will be more resistant towards further sulfonation. The latter will require more drastic conditions and the product will contain the two sulfonic acid groups in the 1,3-position with respect to each other. With reactive substrates, e.g. aromatic hydrocarbons, halides or ethers, mono-chlorosulfonation is often best achieved at low temperature in ftie presence of chloroform, dichloromethane or 1,2-dichloroethane to moderate the reaction and avoid disulfonation. Suter and Weston S described the experimental procedures for the sulfonation of aromatic hydrocarbons, halides and ethers and many early references and details of the synthesis of sulfonic acids and sulfonyl chlorides are included in Suter s comprehensive text." ... 

Bassin, Cremlyn and Swinboume. Details of kinetic and mechanistic studies on sulfonation and chlorosulfonation of aromatic hydrocarbons and other derivatives have been described in Chapter 2. Chlorosulfonic acid is a very active sulfonating agent and when benzene is added to an excess of the reagent at room temperature, benzenesulfonyl chloride is formed (> 70%) with only a trace of diphenyl sulfone. " On the other hand, when an excess of benzene is present, the major products are diphenyl sulfone and benzenesulfonic acid. " ... 

Sulfones are produced as by-products in the sulfonation of aromatic hydrocarbons, probably as a result of the condensation of the sulfonic acid with unreacted hydrocarbon. A more recent modification of preparative value is the preparation of aromatic sulfones by the condensation of aromatic sulfonic acids and aromatic hydrocarbons in a polyphosphoric acid medium. 

Liquid solvents are used to extract either desirable or undesirable compounds from a liquid mixture. Solvent extraction processes use a liquid solvent that has a high solvolytic power for certain compounds in the feed mixture. For example, ethylene glycol has a greater affinity for aromatic hydrocarbons and extracts them preferentially from a reformate mixture (a liquid paraffinic and aromatic product from catalytic reforming). The raffinate, which is mainly paraffins, is freed from traces of ethylene glycol by distillation. Other solvents that could be used for this purpose are liquid sulfur dioxide and sulfolane (tetramethylene sulfone). 

Aromatic hydrocarbons gave products of protonation on dissolving in hydrofluoric acid. Oxidation in aromatic cation radicals did not take place (Kon Blois 1958). Triflu-oroacetic acid is an effective one-electron oxidant (Eberson Radner 1991). Meanwhile, sulfuric acid caused not only dissolution and protonation, but also one-electron oxidation of aromatic hydrocarbons. Sulfonation, naturally, proceeded too (Weissmann et al. 1957). 

It may be expected that other, highly structured solvents with a tri-dimensional network of strong hydrogen bonds, would also permit micelle formation by surfactants, but little evidence of such occurrences has been reported. On the other hand, surfactants in non-polar solvents, aliphatic or aromatic hydrocarbons and halocarbons tend to form so-called inverted micelles, but these aggregate in a stepwise manner rather than all at once to a definite average size. In these inverted micelles, formed, e.g., by long-chain alkylammonium salts or dinonyl-naphthalene sulfonates, the hydrophilic heads are oriented towards the interior, the alkyl chains, tails, towards the exterior of the micelles (Shinoda 1978). Water and hydrophilic solutes may be solubilized in these inverted micelles in nonpolar solvents, such as hydrocarbons. 

A spirothietane sulfone-oxetane is a comonomer in the preparation of polyethers. A polymer obtained from this sulfone in a solution of bis(3,3-chloromethyl) oxetane with phosphorus pentafluoride can be spun to drawable filaments. Thietane sulfone spirocyclic carbonates may be polymerized via the carbonate group to high-molecular-weight solids said to be useful in laminating. Thietane 1,1-dioxide improves the dye receptivity of poly (acrylonitrile), viscose, cellulose acetate, and poly(vinyl chloride). It is also reported to be a stabilizer for nitric acid in oxidizer mixtures for rocket motors. 2-Methylthietane 1,1-dioxide is claimed to be superior to sulfolane (thiolane 1,1-dioxide) in the liquid extraction of aromatic hydrocarbons from mixtures with saturated hydrocarbons. " A number of bis(3,3-alkoxy) thietane 1,1-dioxides have been proposed as intermediates in the preparation of cyanine dyes useful as photographic sensitizers. " ... 

The applications of ruthenium tetroxide range from the common types of oxidations, such as those of alkenes, alcohols, and aldehydes to carboxylic acids [701, 774, 939, 940] of secondary alcohols to ketones [701, 940, 941] of aldehydes to acids (in poor yields) [940] of aromatic hydrocarbons to quinones [942, 943] or acids [701, 774, 941] and of sulfides to sulfoxides and sulfones [942], to specific ones like the oxidation of acetylenes to vicinal dicarbonyl compounds [9JS], of ethers to esters [940], of cyclic imines to lactams [944], and of lactams to imides [940]. 

Concentrated or fuming sulfuric acid (oleum) is widely used for the direct sulfonation of aromatic compounds (see Chapter 7, p. 97).5,6 The active sulfonating agent in sulfuric acid is the electrophile sulfur trioxide, and the sulfonating power of sulfuric acid is proportional to the concentration of S03. Consequently, fuming sulfuric acid, which contains excess sulfur trioxide, is a more powerful sulfonating agent than concentrated sulfuric acid. The sulfonation of an aromatic hydrocarbon is depicted in Scheme 26. 

Nonaqueous organic solvents consist of the following classes of compounds aliphatic and aromatic hydrocarbons and their halogenated and nitro derivatives, alcohols, carboxylic acids, esters, ethers, ketones, aldehydes, amines, nitriles, unsubstituted and substituted amides, sulfoxides, and sulfones. In general, a compound... 

Aromatic hydrocarbons can also be sulfonated by fluorosulfuric acid, if necessary under pressure.184 The dichloride of disulfuric acid has been used occasionally for sulfonation of terpenes,185 and thionyl chloride for that of tertiary aromatic amines.186... 

From the practical standpoint, SO3 and concentrated sulfuric acid have opposite properties as sulfonating agents, as shown in Table 7-3 for the case of aromatic hydrocarbons. Oleum, as might be expected, occupies an intermediate position it is in fact the most widely used industrial sul-fonating agent. 

The sulfonates of aromatic compounds, especially hydrocarbons, are of prime importance respecting both the volume and variety of products and uses. 

When petroleum or kerosene (as the raw materials for gas oil or lubricants) are purified by using oleum or sulfuric acid, a reaction with the aromatic compounds takes place. While these substances were originally seen as waste products, later their chemical structures and surface-active properties were identified, thus leading to special applications for such products. Nowadays, petroleum fractions with a high content of aromatic hydrocarbons are treated with sulfur trioxide to form alkylaryl sulfonates. These products are then transformed into the sodium, ammonium or alkaline-earth salts. They are soluble in oils and therefore are of some importance as additives in lubricants, oil fuels and corrosion-inhibiting oils. Further more, they are also used as auxiliaries in production of fabrics and as dispersants in enhanced oil recovery processes. 

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