Ring current intensities and proton chemical shifts have been calculated for a series of condensed aromatic hydrocarbons including biphenylenes. The calculations show that an induced paramagnetic ring current occurs in the 4-membered ring of each of the biphenylenes studied and this effect accounts for the observed spectra. PMR measurements on 1-mono-, 2-mono- and 2,3,6,7-tetra-deuteriated biphenylene prove that the chemical shifts of the 1- and 2-protons are at δCDCl3 6.60 and 6.70 respectively and not vice versa as assumed by previous authors.

Reaction of biphenylene with butyl-lithium gives a mixture of 1- and 2-lithiobiphenylene in the approximate ratio of 20 : 1. This mixture has been used to prepare the following 1-substituted biphenylenes: pentanoyl, methoxycarbonyl, carboxy, acetyl, formyl, hydroxymethyl, bromo-methyl, methyl, hydroxy, methoxy, acetoxy, allyloxy, carboxymethoxy, and iodo.