5-di-t-butylphenylaminyl radical (2) with unsaturated aromatic and aliphatichydrocarbons has been carried out in degassed benzene at 75°C. The reactions of 2 with unsaturated aromatic hydrocarbons gave 1:1, 1:2, and 2:1 adducts of 2 and the hydrocarbons in fair to good yields. On the other hand, in the reactions of 2 with unsaturated aliphatichydrocarbons, hydrogen-abstraction by 2 from the hydrocarbons was the major