RELATIVE YIELDS OF EXCITED KETONES FROM SELF-REACTIONS OF ALKOXYL AND ALKYLPEROXYL RADICAL PAIRS

Article abstract of DOI:10.1021/ja00221a035

We have measured the ratios of excited ketones that arise from the self-reactions of alkoxyl (2R₁R₂CHO^.) and peroxyl (2R₁R₂CHO^. radicals.This was accomplished by measuring the chemiluminescence emission from solutions of R₁R₂CHO2H, or R₁R₂CH2 and O2, in the presence of a free-radical initiator trans-RON=NOR, in which R=t-Bu or R₁R₂CH in paired experiments.The excited states were trapped with 2-tert-butyl-9,10-dibromoanthracene or another fluorescent derivative of anthracene.The peroxyls were less efficient sources by 17percent, 48percent, and 42percent than the alkoxyls for the cases in which R₁R₂C=O was acetophenone in ethylbenzene, cyclohexanone in cyclohexane, and 1-tetralone in t-BuPh and in t-BuOH, respectively.The activation energy for formation of excited 1-tetralone (T_o and/or S₁) from two 1-tetralylperoxyl radicals was 6 +/- 3 kcal/mol higher than for production of excited state from the corresponding pair of alkoxyl radicals.The results are consistent with but do not demand the hypotesis that excited carbonyl states arise in peroxyl terminations by way of alkoxyl pairs.