The present paper is a continuation of the study of the rates of dissociation of pentaarylethanes (1, 2, 3). Six new pentaarylethanes of the type (CgH6)3C-CH (CgH6) R have been synthesized in which R is 5,6,7,8-tetrahydro-1-naphthyl (I), 1,2,3,4-tetrahydro-9-phenanthryl (II), 4-methyl-l-naphthyl (III), 4-fluoryl (IV), 5,6,7,8-tetrahydro-2-naphthyl (V), and 1-fluoryl (VI).The rate constants (k) and half-life periods (ti) of these 1,1,1,2-tetraphenyl-2arylethanes in the reaction with iodine (2) at 80°have been determined; the values for these constants are shown beneath the formulas for the groups