Sulfonation with hydrogen fluoride

SAFETY PROFILE Poison by ingestion and intraperitoneal routes. May be corrosive to skin, eyes, and mucous membranes. Explosive reaction with ethyl vinyl ether. Incompatible with hydrogen fluoride. When heated to decomposition it emits toxic fumes of SOx. See also SULFONATES. 

Fluorocarbons are made commercially also by the electrolysis of hydrocarbons in anhydrous hydrogen fluoride (Simons process) (14). Nickel anodes and nickel or steel cathodes are used. Special porous anodes improve the yields. This method is limited to starting materials that are appreciably soluble in hydrogen fluoride, and is most useflil for manufacturing perfluoroalkyl carboxyflc and sulfonic acids, and tertiary amines. For volatile materials with tittle solubility in hydrofluoric acid, a complementary method that uses porous carbon anodes and HF 2KF electrolyte (Phillips process) is useflil (14). 

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. 

Fluorinated and Ghlorfluorinated Sulfonic Acids. The synthesis of chlorinated and fluorinated sulfonic acids has been extensively reviewed (91,92). The Hterature discusses the reaction of dialkyl sulfides and disulfides, sulfoxides and sulfones, alkanesulfonyl haHdes, alkanesulfonic acids and alkanethiols with oxygen, hydrogen chloride, hydrogen fluoride, and oxygen—chloride—hydrogen fluoride mixtures over metal haHde catalysts, such as... 

Formal replacement of hydrogen by fluorine takes place in the a-position of a ketone by treatment of enol acetates with triethylamine tris(hydrogen fluoride).51-55 The kinetically favored isomers are formed.51,55 Furthermore, benzylic positions bonded with an electron-withdrawing group (ketone, ester, nitrile, sulfonate) can be fluorinated electrochemically.51" 6-58 There are also various examples of the preparation of a-fluorosulfides front sulfides.51... 

Fluorine is used for the fluorination of sites x to sulfoxides with simultaneous oxidation of the sulfoxide moiety to a sulfone. The electrophilic fluorine attacks the electron lone pairs of the sulfur atom with a consequent loss of hydrogen fluoride forming an S-fluorosulfoxy alkene. A second molecule of fluorine adds across the newly formed double bond resulting, after hydrolysis, in an a-fluoro sulfone 12.88 This reaction is used for the construction of a fluorocy-clopropane derivative 13 which is essential in the synthesis of one of the most promising members of the quinolinecarboxylic acid antibiotics.89... 

Different kinds of alkyl and aryl sulfonates 7 have been transformed to the fluorides 8 under fairly mild conditions with potassium fluoride in polyethylene glycol 400.145 No trace of elimination products, normally found due to attack of a second mole of potassium fluoride on the fluoroalkane eliminating hydrogen fluoride, is observed and the hydrolysis product is present only in 4% yield. No displacement of the tosylate group occurred for neopentyl tosylate. 

Hydrogen fluoride is also used in the alkylation of benzene with linear olefins to produce detergent alkylate for sulfonation to produce detergents. This acid is now being replaced in some plants by fluorided silica-alumina catalysts in the U.O.P.-Petresa process.9 This type of catalyst may be applicable to the alkylation of isobutane with butenes. 

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