Sulfones, alkylation aryl, from aromatic

Sulfur dioxide (see above) as well as S02, SO , and SOj have been used as building blocks in three-component sulfone syntheses. It has long been known that aromatic sulfinic acids are easily available from diazonium salts and sulfur dioxide under copper catalysis . Mechanistically, aryl radicals as reactive intermediates add to sulfur dioxide generating arenesulfonyl radicals, which either take up an electron (or hydrogen) yielding a sulfinic acid or add to an olefinic double bond yielding final y -halogenated alkyl aryl sulfones (equation 78). 

The removal of AAT sulfur compounds from the diesel fuel feedstock by extractive desulfurization (EDS), either adsorption or solvent extraction, is a viable alternative to HDS." This approach is based on the polarity difference between the AAT family of compounds and the hydrocarbons found in the diesel fraction. Because AATs comprise several dozen different compounds, they represent a range of solvent polarities, in some cases quite similar to the aromatic compounds found in diesel fuel. The critical polarity difference between individual hydrocarbon and thiophenic compounds is therefore variable, and in some cases may be insufficient to allow a functional separation by extraction. Polarity difference can, however, be increased by oxidizing the thiophenic sulfur to the corresponding more polar mono- and dioxides, the alkylated-aryl-thiophene-sulfoxide or sulfone (AATS). This in turn facilitates the separation, and several EDS processes therefore are designed to oxidize the AAT before extraction of the sulfur." ... 

Incidentally, 34 contributes more to the hybrid than 35, as shown by bond-distance measurements. In benzenediazonium chloride, the C—N distance is 1.42 A, and the N—N distance 1.08 A, which values fit more closely to a single and a triple bond than to two double bonds (see Table 1.5). Even aromatic diazonium salts are stable only at low temperatures, usually only < 5°C, although more stable ones, such as the diazonium salt obtained from sulfanilic acid, are stable up to 10 or 15°C. Diazonium salts are usually prepared in aqueous solution and used without iso-lation, although it is possible to prepare solid diazonium salts if desired (see 13-23). The stability of aryl diazonium salts can be increased by crown ether complexion. For aromatic amines, the reaction is very general. Halogen, nitro, alkyl, aldehyde, sulfonic acid, and so on, groups do not interfere. Since aliphatic amines do not react with... 

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