Alkyldichloroboranes in inert solvents react remarkably rapidly with 0.5 molar equiv of oxygen, either at 0 or-78". The reaction is strongly inhibited by iodine and must involve a free- radical chain process, yet the product contains little peroxide. In diethyl ether the reaction proceeds readily with the uptake of 1 molar equiv of oxygen. The product is readily hydrolyzed to the corresponding alkyl hydroperoxide. This procedure provides a ...