Dicarbonium ions in the biphenyl series

✍ Scribed by Harold Hart; Theodore Sulzberg; Richard H. Schwendeman; Robert H. Young

• Book ID: 104213170
• Publisher: Elsevier Science
• Year: 1967
• Tongue: French
• Weight: 191 KB
• Volume: 8
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)71580-2

✦ Synopsis

Some time ago (1) we reported on dicarbonium ions of the triarylmethyl type in which the sites of ionization were attached ortho, meta or para on a single benzene ring. We now wish to record results (2) on the spectra and pK R++ '6 of dicarbonium ions in which the ionization sites are separated by two benzene rings, particularly since our approach differs from and complements one which was recently reported in this journal (3). Carbinols corresponding to dications I-IV were synthesized, and their spectra determined as a function of acid strength in aqueous sulfuric acid. The spectra and pK R++ '8 of the dications are given in Table I (4). \ Once can view ions I-III as having been derived by joining two trityl cations (Tr+) respectively at the para, meta or ortho positions. If one ignores the question of coplanarity of the biphenyl system, resonance structures can be drawn for I and III in which both positive charges can be distributed in any of the six rings, whereas the two trityl cations in II are, to a first approximation, isolated. Expected twisting should also isolate the charges in III. Assumptions were w = 1.4, 6 -8, co8 B for non-planar conformations. 'Outer' rings were assumed to be twisted 30' [compare 23', D. E. Reilly and H. P. Leftin, J. Phys.