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

Abstract

The crystal structure of p-hydroxybenzoic acid monohydrate, CTH6Oa.H20, determined from photographic data [Fukuyama, Ohkura, Kashino & Haisa (1973). Bull. Chem. Soc. Jpn, 46,[804][805][806][807][808], has been refined to R = 0.0414 on 1454 counter reflexions. Crystals are monoclinic, space group P2~/a, with a = 17.752 (9), b = 6.442 (2), c = 6.731 (3) A, fl= 105.48 (6)°, Z=4. The benzene ring has approximate C2, (mm) symmetry and shows a slight quinoidal shortening of the central C-C bonds. The internal angles at the ipso positions of the ring are aon = 120.5 (1) °, acoon = 119.4 (1) °.

Structural studies of benzene derivatives. VII. Refinement of the crystal structure of p-dinitrobenzene

“…Bond distances and angles obtained by the various refinements are compared in Table 2, which also gives the weighting schemes and the values of R and R w. It is apparent that refinement (4) [w = 1/(a + blFol + ClFol2)], although affording a slightly higher R, is superior to refinements (1) to (3) in that it yields a better approximation to the axially symmetrical geometry expected on chemical grounds. A similar observation has been reported for other benzene derivatives (Colapietro, Domenicano & Pela Ceccarini, 1979;Colapietro, Domenicano & Marciante, 1979;Colapietro, Domenicano & Portalone, 1980); here, however, the effect is quite marked and worth presenting in some detail. Refinement (4) is also that which gives the lowest dispersion for the mean values of the minimized function over ranges of either I Fol or sin 0/2.…”

Structure of p-hydroxybenzoic acid and p-hydroxybenzoic acid-acetone complex (2/1)

“…In the pure acid, H atoms H1, H2 and H5, and O atom 02 deviate by the largest amounts [0.120 (6) The structures of p-hydroxybenzoic acid and phydroxybenzoic acid-acetone complex reported here, as well as that previously reported for the monohydrate grown from wet acetone solution (Beilsteins Handbuch der Organischen Chemie, 1927;Fukuyama, Ohkura, Kashino & Haisa, 1973;Colapietro, Domenicano & Marciante, 1979), show that care must be exercised in growing uncomplexed crystals from solvents, especially when hydrogen-bonded complexes may be formed, p-Hydroxybenzoic acid monohydrate is obtained when crystals are grown in aqueous and in acetone solution, since even reagentgrade acetone contains some water [1% (Perrin, Armarego & Perrin, 1980)]. …”

“…However, the crystallographic characterization of these compounds is incomplete, and the purity of the chemicals is often questionable since the data are quite old and since these compounds are notoriously difficult to purify, as they complex with many solvents and are easily oxidized (Ebisuzaki, Askari, Bryan & Nicol, 1987;Perrin, Armarego & Perrin, 1980). The crystal structure of p-hydroxybenzoic acid has not previously been reported (Steinmetz, 1914), although that of the monohydrate has been published (Colapietro, Domenicano & Marciante, 1979;Fukuyama, Ohkura, Kashino & Haisa, 1973). As part of our research on the monosubstituted phenols, we report on the structure of pure p-hydroxybenzoic acid and on the structure of the 2/1 acetone complex.…”

Crystal structure and spectroscopic properties of the complex of trigonelline hydrate with p-hydroxybenzoic acid

“…The O(4) atom of HBA carboxylic group does not participate in the hydrogen-bond network but only in the weak C-HÁ Á ÁO(4) contact (Table 3). HBA itself crystallizes in monoclinic space group P2 1 /a as a monohydrate [28,29]. Pairs of HBA molecules form dimers by the hydrogen bonds between Table 1 Crystal data and structure refinement for the 1:1 complex of trygonelline hydrate with p-hydroxybenzoic acid (1).…”