Calculation of the influence of various radical pairs on the CIDNP of the decomposition products of asymmetric diacyl peroxides

Radical Nature of Pathways to Alkene and Ester from Thermal Decomposition of Primary Alkyl Diacyl Peroxide

“…However, the former investigation suggests that the decarboxylation rate for the propanoyloxy radical is 2 × 10 9 s -1 . This implies that it should be possible to observe net CIDNP polarization in photolysis or thermolysis of dipropanoyl or other primary peroxides which is contrary to the results reported previously …”

“…The results are summarized in Table . Decomposition of 0.1 M 2 in HCA (hexachloroacetone) at 140 °C was examined because this is the concentration, solvent, and temperature often chosen for CIDNP studies. , Furthermore, HCA is usually considered to be capable of efficient scavenging of radicals escaping recombination, thereby assuring that alkane 6 arises solely from geminate pairs. It was determined, however, that HCA is not as efficient a scavenger as BrCCl 3 .…”

“…Much less certain is the decarboxylation rate of RCO 2 • , when R is primary, secondary, or tertiary alkyl or benzyl. The acetoxy radical (R = CH 3 ) decarboxylation rate has been estimated from product yields and CIDNP enhancement factors to be 10 9 s -1 at 80 °C with an activation energy of approximately 7 kcal/mol. Estimates for the decarboxylation rate of RCO 2 • with R = CH 3 , CH 3 CH 2 , (CH 3 ) 2 CH, (CH 3 ) 3 C, PhCH 2 , and PhCH 2 CH 2 were recently obtained by comparison with electron-transfer rates within the naphthylmethyl−acyloxy radical pairs, assumed independent of the nature of R, and calibrated by the known decarboxylation rate of 9-methylfluorenoyloxy radical .…”