Sulfonylium

The sulfonylation mechanism involves a two-stage reaction, as shown in Scheme 6.4. The sulfonylium cation ArS02+ attacks the carbon on the aromatic nucleus to generate an intermediate complex, which subsequently decomposes to afford the final product by eliminating a proton. It is postulated that the effective sulfonylating agent is the sulfonylium salt generated by action of the Lewis-acid catalyst on the sulfonyl halide.18... 

Cationic propagating species that contain positively charged sulfur atoms include sulfonium and sulfonylium cations. Sulfonium cations have been suggested to be involved in the synthesis of poly(phenylene sulfide) (PPS). 

Aromatic polysulfones are a commercially important class of thermoplastic polymers [127]. They have highly desirable qualities such as chemical inertness, thermal stability, and flame retardency [128,129]. Although a number of methods are available for the synthesis of polysulfones [130,131,132], step polymerization methods are the most widely used industrially [127]. Polysulfones have been synthesized with the involvement of sulfonylium cations as propagating species. 

The reagents (R = CH3, C2HS) react with activated arenes without Friedel-Crafts catalysts to form alkyl aryl sulfones. Alkylation rather than sulfonylation is observed when R = CH(CH3)2. Sulfonylation involves the sulfonylium ion RSO2 when R is a secondary alkyl group the ion readily loses SO2 to give the carbonium ion. ... 

There are two industrial processes for producing polyether sulfones. One can start either with AB monomers or proceed with a polycondensation of AA and BB monomers in the electrophilic substitution of aromatically bound hydrogen by sulfonylium ions ... 

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