Abstract
The thermal oxidative degradation of polyethylene glycol (PEG) is known to occur in an oxygen atmosphere at elevated temperatures. In this study, PEG radicals assumed to result from thermal oxidative degradation are successfully applied, in combination with compressed CO~2~, to initiate a range of freeโradical reactions, such as selective formylation of primary and secondary aliphatic alcohols, oxidation of benzylic alcohols, benzylic C๏ฃพC bond cleavage, and benzylic sp^3^ C๏ฃฟH oxidation, demonstrating enormous synthetic potential in a costโefficient, practically useful, and environmentally friendly manner; not requiring any catalyst or additional freeโradical initiator. We find that both PEG and molecular oxygen are prerequisites in order to perform these reactions smoothly. Given that dense CO~2~ is immune to freeโradical chemistry; it is an ideal solvent for such reactions. As a result, compressed CO~2~ allows reactions initiated by PEG radicals to be tuned by subtly adjusting reaction parameters such as the CO~2~ pressure, thereby enhancing the product selectivity. By attaining a high selectivity towards the desired products this methodology is practical for organic syntheses.