Arene thiolates, reaction with halogen

The reaction of trifluoromethyl iodide with arene thiolates provides trifluoromethyl aryl sulfides via a single electron transfer (SET) reaction rather than the SN2 reaction, which is the only formal mechanism (Scheme 2.31). In general, perfluoroalkyl (Rf—X), ferf-alkyl, and vinyl and aromatic halides are strongly deactivated for the replacement of halogens with... 

In contrast to the IIT mechanism, the clement effect on the Arens path is expected to be A (I) > A (Br) > A (C1) as is also the case with S 2 reactions of alkyl halides (Table 25) . This reactivity order has been observed in the reactions of l-halo-2-(2-thienyDacetylenes with sulphides and thiolates in methanol-water in which the C—X bond is presumably broken in the rate-determining step by attack on halogen (see Section Il.C.l.d). In both 5 n2 and halogen abstraction reactions, the magnitude of the element effect is quite large (Table 25). 

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