Synthesis and structure of nitro-substituted poly(phthalidylidenebiphenyl-4,4′-ylene)s

Nitro‐substituted derivatives of poly(phthalidylidenebiphenyl‐4,4′‐ylene) (l), containing a controlled amount of nitro groups within 0,3 and 3,0 per mol of repeating unit, were prepared by nitrations under various conditions. The nitration was carried out either in nitric acid or by potassium nitrate and nitric acid in sulfuric acid solution. 13C NMR spectroscopy was used to study the structure of the resulting nitroderivatives. The trinitroderivative was found to contain the nitro groups in position 6 of the phthalide moiety and in positions 2 and 2′ of the biphenylylene unit. At lower degrees of nitration, some di‐, tri‐ as well as unsubstituted units are present in the polymer.