Reactions of the α-methoxybenzyl radical in carbon tetrachloride and in other solvents. Carbon tetrachloride as a chlorinating agent
The α-methoxybenzyl radical, generated from benzyl methyl ether at 110° by the action of t-butoxy-radicals (from di-t-butyl peroxide) in an excess of the ether as solvent, undergoes mainly dimerisation, and breaks down to benzaldehyde to a small extent. In the presence of carbon tetrachloride as solvent, the radical in part breaks down, and in part abstracts a chlorine atom from the solvent to form Ph·CHCl·OMe which at 110° suffers thermolysis to benzaldehyde, but which can be isolated if the reaction is carried out at 60°(using t-butyl hyponitrite as the source of t-butoxy-radicals). Evidence is presented to show that, with carbon tetrachloride as solvent, the main hydrogenabstracting radical is the trichloromethyl radical. In pentane, octane, and hexadecane as solvent, the tendency of the radical to undergo dimerisation, which is the preponderant reaction, increases with increasing viscosity of the solvent. In diphenyl ether, diphenyl monosulphide, and tetrachloroethylene, however, the radical suffers extensive breakdown to benzaldehyde. This behaviour is attributed to complexing of the radical with these latter solvents, rendering dimerisation more difficult.