Arenesulphonyl radicals

Arenesulphinylation 264 Arenesulphinylethanes, synthesis of 267 2-Arenesulphonyl-3-aryloxaziridines, as oxidizing agents 254 Arenesulphonyl azides, reactions of 641 At-Arenesulphonyliminopyridinium betaines, mass spectra of 160-162 Arenesulphonyl radicals 215, 1091 Aryldiazonium salts, reactions of 280, 281 Aryl(methylsulphinyl)(methylthio)alkenes, synthesis of 614... 

A detailed study by ESR of the arenesulphonyl radicals 1 has been reported following the irradiation of the corresponding chlorides in toluene9. The spin distribution in the radicals was determined as was the rotation around the S—C aryl bond. A similar study was performed using the sulphonamidyl chlorides 2. This clearly showed that the radical was still sulphur-centred and that there was little interaction with the adjacent nitrogen10. A review of the reactivity and the formation of sulphur-centred radicals has been published11. 

Table 9 contains the data for radical cations of arenesulphonic acids and arenesulphonyl fluorides40,41. 

Ab initio MO calculations at the 6-31G level verify these conclusions and reveal that (i) disproportionation of arenesulphinyl radicals to arenesulphonyl and arenethiyl radicals is exothermic by —13.6kcalmol-1 and (ii) that the sulphenyl sulphinate structure 57 is 28kcalmol 1 more stable than the wc-disulphoxide 58108. 

Thus, the iV-(arenesulphonyl)piperidine 82 reacts with tributyltin radicals to form, at about 90 °C, equal amounts of the rearranged product 83 and the product of arenesulph-onyl ring substitution 84 (equation 60). Temperature has a profound effect on the product ratio at 190 °C, the rearranged product dominates giving a ratio of 7 1. The formation of 83 is thought to involve 85. 

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