The Crystal and Molecular Structure of p-Hydroxybenzoic Acid Monohydrate

Abstract

The crystal and molecular structure of p-hydroxybenzoic acid monohydrate has been determined by a single crystal X-ray analysis. The crystals are monoclinic, space group P21⁄a, Z=4, with a=17.79, b=6.39, c=6.79 Å, and β=105.6°. The structure was solved by the Patterson and Fourier methods, and refined by the block-diagonal least-squares method to a final R value of 0.086 for 806 non-zero reflections. Pairs of acid molecules form dimers by the hydrogen bonds between carboxyl groups (2.678 Å). The dimers are held together by the hydrogen bonds between phenolic hydroxyl groups and water molecules (2.595 and 2.823 Å); these hydrogen bonds extend around two-fold screw axes to make up layers of the dimers parallel to the (401). The layers are linked by the additional hydrogen bonds between carbonyl oxygens and water molecules (2.823 Å).

Structural studies of benzene derivatives. VI. Refinement of the crystal structure of p-hydroxybenzoic acid monohydrate

“…Oscillation and Weissenberg photogralShs confirmed the crystal data given by Fukuyama et al (1973). A crystal ca 0.38 x 0.58 × 0.24 mm was sealed in a glass capillary to prevent the loss of water and mounted on a Syntex P21 diffractometer.…”

“…The cell parameters were refined by least squares from the measured 0 values for 22 accurately centred reflexions, lying in the 8 range 18-24 o and well distributed in reciprocal space. The values obtained are compared in Table 1 with those of Fukuyama et al (1973).…”

“…The positional parameters given by Fukuyama et al (1973) for the non-H atoms were used as a starting set (R = 0.198). Isotropic and then anisotropic leastsquares refinement, followed by the introduction of the H atoms as given by a difference synthesis, lowered R to 0.064.…”

“…0567-7408/79/092177-04501.00 Kashino & Haisa (1973). The refinement, based on 806 reflexions from photographic records, was by blockdiagonal least squares and led to a final R of 0.086.…”

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AbstractThe crystal structure of p-hydroxybenzoic acid monohydrate, CTH6Oa.H20, determined from photographic data [Fukuyama, Ohkura, Kashino & Haisa (1973). Bull.

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