The title structure, 4-amino-benzoic acid 4-methyl-pyridine/4-methyl-pyridinium 4-amino-benzoate 0.58/0.42, 0.58(C6H7N·C7H7NO2)·0.42(C6H8N+·C7H6NO2-), has been redetermined from the data published by Kumar et al. (2015 ▸). Acta Cryst. E71, o125-o126. The improvement of the present redetermination consists in the introduction of disorder of the methyl group over two positions as well as in the correction of the positional parameters of the hydrogen atoms that are involved in the O-H⋯N or N-H⋯O hydrogen bonds. After the correction, the hydroxyl hydrogen atom turned out to be disordered over two positions about the centre of the O⋯N bond, which is relatively long [2.642 (2) Å], while the H atoms of the primary amine group account more realistically for the hydrogen-bond pattern after the removal of the positional constraints. All the O-H⋯N or N-H⋯O hydrogen bonds which are present in the title structure are of moderate strength.

Inst of Physics of the Czech Academy of Sciences Na Slovance 2 182 21 Praha 8 Czech Republic

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