Oligomers from biphenyl,biphenyl-d10, or p-terphenyl with aluminium chloride-cupric chloride: Mechanism,ESR, and conductivity

Biphenyl and biphenyl-d₁₀ were coupled by aluminum chloride-cupric chloride. For the two systems, the yields of p-quaterphenyl, p-sexiphenyl, and sublimation residue were compared. The results, which have mechanistic significance, are similar to those reported earlier for benzene versus benzene-d₆; that is, a decrease in DP for the deuterated substrate. p-Sexiphenyl, obtained from biphenyl or p-terphenyl and aluminum chloride-cupric chloride, displayed a concentration of 3 × 10¹⁷ spins/g in ESR. There was little or no change in spin density after sublimation or crystallization. Even after drastic purification by a variety of techniques the radical character persisted. Biphenyl was polymerized by aluminum chloride-cupric chloride at temperatures in the 50–155°C range. Processable polymers with m- and p-phenylene linkages were produced. When doped with AsF₅, the highest conductivity obtained was 7.3 × 10^?2 Ω^?1 cm^?1.