Electrophilic substitution of two monohomoperylenes and perylene

Article abstract of DOI:10.1002/recl.19931121105

Various types of electrophilic substitution of monohomoperylene (1) and its 11,11-difluoro derivative (2) have been studied, viz, bromination, nitration, acylation, formylation and sulfonation.Bromination with N-bromosuccinimide (NBS) of 1 in dichloromethane leads to initial substitution mainly at the α position 2 and 10, i.e., of the annuleno moiety, followed by further substitution of the β positions 4 and 8 of the same moiety, and of the α positions 2' and 10' of the naphthaleno moiety.Reaction of 1 with 5.0 mol-equiv. of NBS yields 2,4,8,10,2'-pentabromo-1 in 46percent yield.Sulfonation of 1 with SO3 in dichloromethane using 1.2 mol-equiv. of dioxane as reactivity moderator leads to the formation of 1-2-sulfonic acid (1-2-S), 1-2,10-S₂, and the intermediate ? complex 6.Sulfonation of the 11,11-difluoro derivative 2 leads to the formation of 2-2-S, 2-2,10-S₂ and 2-2,10-disulfonic anhydride (7), together with small amounts of 2-2,2'-S₂ or/and 2-2,10'-S₂.The other types of electrophilic substitution of 1 and 2 studied were found to proceed similarly, in that the initial substitution occurs at the 2-position and the subsequent one at the 10-position, i.e., peri to the primarily introduced substituent.The chemical behaviour (i.e., the substitution pattern and relative reactivity) of the two monohomoperylenes 1 and 2 have been compared with that of 1,6-methano<10>annulene (3), its 11,11-difluoro derivative (4), and perylene (5).For example, the sulfonation reactivity ratio of the naphthalene to the <10>annuleno moiety is significantly greater for 2 than 1, as predicted on the basis of the higher sulfonation reactivity of 3 compared to 4.