Pseudosymmetry in 2,5-Dimethyl-1,4-benzenediol

The title compound, C₈H₁₀O₂, was prepared from diacetyl by a high temperature and pressure reaction. Pseudosymmetry in the structure results in diffraction symmetry enhancement for half the reflections and the possibilility of twinning and stacking faults. The structure consists of two independent but pseudosymmetrically related P2₁/c substructures, each having centrosymmetric molecules on centres of inversion which are strongly hydrogen bonded to symmetry-related molecules to form layers perpendicular to c*. The structure may be described as an occupancy modulation, ordering a disordered parent structure in Pnma symmetry to form, upon change of axes, the P2₁/c structure reported. The hydroxyl H atoms have two site options corresponding to alternative hydrogen-bonding patterns and the methyl H atoms in one substructure are rotationally disordered.

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