Abstract Thermolysis of tert-butyl hydroperoxide (1) in nitrogen with an excess of benzene in the temperature range 200-300 C, leads to biphenyl (2) as the only observable benzene- derived product. With chlorobenzene, dichlorobiphenyls (4) are formed, together with chlorobiphenyl (5), ca. 12% on 4, and phenol (20-25% on 4); chlorophenols are not produced. The use of ca. equimolar quantities of iodine based on 1 results in formation of ...