Abstract
On basis of the discovery of hindered amine light stabilizers (HALS) and their derivatives that reduce photo-excited quinone to corresponding dihydroxy benzene, resulting in photo-stabilization of plastics, hydrogenated benzoins, which seem to have mobile hydrogens were molecular-designed as substitutes of HALS. The hydrogenated benzoins were found to work like HALS, limited to a few fundamentally characteristic properties. Such activities of non-substituted and 4, 4'-dichloro-substituted hydrogenated benzoins were weaker than HALS, but the hydrogenated benzoins having 4, 4'-dimethyl or 4, 4'-dimethoxy substituents could retard autoxidation of styrene, at the beginning of the reaction, to the degree comparable to HALS. The nuclear substituents, having more electron-donating properties, were more effective for the activities of hydrogenated benzoins.
