Irradiation of 1, 2, 4, 5-benzenetetracarbonitrile (TCB) in the presence of several donors (some 2-t-butyl-1, 3-dioxolanes, pivalic acid, t-butyltrimethylstannane, t-butyldimethylsilyl n- octyl ether) leads to fragmentation of the donor radical cation to give the t-butyl radical. When the irradiation is carried out in the presence of electron-withdrawing substituted alkenes, the radical is trapped and the adduct radical either couples with TCB-•(the overall ...