Acyl peroxides, photolysis

Photolysis of acyl peroxides apparently leads to formation of alkyl radicals and carbon dioxide as observed by ESR (196) ... 

Bennett and coworkers (138) have prepared the acetyl radical CH CO by the reaction between Na and acetyl chloride and have obtained an isotropic value of 5.1 gauss for the proton splitting. An ESR spectrum attributed to CH CO with 16 gauss was earlier reported during photolysis of biacetyl (276) in a solid matrix. Recently a series of benzoyl 6-radicals (277) have been observed in the liquid photolysis of the corresponding benzaldehyde in a cyclopropane solution containing di-t-butyl peroxide. For the first time, it is possible to study in these radicals the delocalization of the unpaired electron from the acyl 6-system into the adjacent phenyl ir-system. The significant conclusion from this study is the... 

The diacyl peroxide has been used as a source of FC02-radicals. Fluorination of the peroxide by photolysis with F2 gives access to the acyl hypofluorite, FC(0)0F, bp ca. —55 °C, in reasonable yields. The acyl hypofluorite is a precursor to a cyclic isomer, the simplest perfluorodioxirane, CF2O2, made by the method shown in equation (59). ... 

A thermal acylation via a radical chain sequence was achieved for chloranil (38) and benzaldehyde (similar to Scheme 11) at elevated temperatures using benzoyl peroxide as a radical initiator. As an example, the monoester 39 was readily obtained in yields of 75 to 80% at 120°C. Thus, Schenck concluded that a free radical chain mechanism during photolysis should occur solely at higher temperatures. ° ... 

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