organic compounds
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The asymmetric unit of the title compound, C6H7NO3, contains two molecules (A and B) related by a non-crystallographic twofold pseudo-axis. The molecules are joined in the (AABB)n manner by O—HO hydrogen bonds between their hydroxy groups, thus forming C(2) chains along the a-axis direction. Neighboring molecules of the same kind (A and A, or B and B) are related by inversion centers, so that all hydroxy H atoms are disordered other two sets of sites with half occupancies (superimposed O—HO and OH—O fragments). The molecules are further linked by C—HO interactions, which can be considered to be weak hydrogen bonds.