I1 Mascarelli assigned the structure 2-chlOr0-3', 4'-dinitrobiphenyl on the basis that it yields on oxidation 3, 4-dinitrobenzoic acid. On repeating this work we find that I1 is in fact unchanged by prolonged refluxing with chromic anhydride in presence of vanadium oxide in acetic acid solution. Since I on further nitration yields 11, it is evident that one nitro group is in the 4'-position relative to chlorine. Reduction of 11, followed by oxidation, brought about ...