Diaryliodonium salts thermal decomposition

A mechanism with similar propagation steps to the usual S l has been proposed in the reaction of diaryliodonium salts with triphenylphospliine in this case, both the nucleophile and leaving group are neutral. This reaction is catalysed by light or by the thermal decomposition of di- -butyl peroxalate. The propagation steps that have been proposed in... 

Reactions of diaryliodonium salts with various organochalcogen anions led to the arylchalcogen derivatives. (Table 5.7) The anions of sulfur compounds afford generally the 5-aryl derivatives. Sometimes the intermediate iodanes can be isolated. Examples are the reaction of dithiocarbamate and xanthate salts with diaryliodonium. Upon heating, the dithiocarbamate derived iodane afforded the aryldithiocarbamates.133 Thermal decomposition of the xanthate derived iodanes gave mixtures of arylxanthates and diaryldisulfides. ... 

The arylation of nucleophiles by reaction with diaryliodonium salts can be greatly facilitated by copper catalysis. This effect was observed by Beringer et al in the thermal decomposition of diaryliodonium halides as well as by Caserio et al in the hydrolysis of diaryliodonium salts. 2 jhe thermal decomposition of diphenyliodonium chloride shows a reduced activation energy upon copper catalysis Ea = 19 kcal/mole in Methylene glycol in the presence of CuCl instead of 31 kcal/mole in the absence of catalyst.From the synthetic point of view, the copper-catalysed arylation with diaryliodonium salts has been particularly useful in the case of a number of reactions involving heteroatomic nucleophiles, in particular for 5-, 5e-, O- and N-arylation reactions. 

Crivello et al. [32], described arylsulfonium salts with two or three photoactive groups in the same molecule. These were prepared via arylation of thiophenoxyaryl sulfides by the thermal decomposition of diaryliodonium salts. The extended conjugation of the chromophores introduced long wavelength absorption bands. 

The possibility of the synthesis of aryl fluorides by thermal decomposition of diaryliodonium tetrafluorobo-rates was first demonstrated by Van der Puy in 1982 [70]. It was found that the reactions of diphenyliodonium salts with different anions (BF4, CFsCOO", TsO , Cl ) in DMF in the presence of KF upon heating afford fluorobenzene in 11-85% yield. The lowest yield (11%) was observed in the reaction of diphenyliodonium chloride with KF in DMF at 115 °C, while the thermolysis of Ph2l+BF4 in the presence of KF at 160-170 °C without solvent gave PhF in 85% yield. The formation of benzene (2-9%) due to a parallel radical decomposition process was also observed in all these reactions [70],... 

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