Crystallographic identification of an unexpected by-product in an Ullman's reaction toward biphenyls: 1-(4-hexyloxy-3-hydroxyphenyl)ethanone

Abstract

The synthesis of 3,3′-diacetoxy-4,4′-bis(hexyloxy)biphenyl following the nickel-modified Ullmann reaction yielded a by-product which was identified successfully by crystallographic analysis as 1-(4-hexyloxy-3-hydroxyphenyl)ethanone, C14H20O3. This unexpected nonbiphenyl by-product exhibited IR, 1H NMR, 13C NMR and COSY (correlation spectroscopy) spectra fully consistent with the proposed structure. The compound crystallized in the orthorombic Pbca space group, with two independent formula units in the asymmetric unit (one of which was slightly disordered), and showed a supramolecular architecture in which molecules linked by hydroxy-ethanone O - H⋯O interactions are organized in columns separated by the aliphatic tails.