A third monoclinic polymorph of 3,4,5-trihy­droxy­benzoic acid monohydrate

Güneş Demirtaş; Necmi Dege; Orhan Büyükgüngör

doi:10.1107/S1600536811018848

. 2011 May 25;67(Pt 6):o1509–o1510. doi: 10.1107/S1600536811018848

A third monoclinic polymorph of 3,4,5-trihydroxybenzoic acid monohydrate

Güneş Demirtaş ^a,^*, Necmi Dege ^a, Orhan Büyükgüngör ^a

PMCID: PMC3120380 PMID: 21754875

Abstract

The title compound, C₇H₆O₅·H₂O, is a new polymorph of the structures reported by Jiang et al. (2000 ▶) [Acta Cryst. C56, 594–595] and Okabe et al. (2001 ▶) [Acta Cryst. E57, o764–o766]. The gallic acid molecule is essentially planar (r.m.s. deviation = 0.550 Å). An intramolecular O—H⋯O hydrogen bond occurs in the gallic acid molecule, which is linked to the water molecule by a further O—H⋯O hydrogen bond. In the crystal, the components are linked by O—H⋯O hydrogen bonds. The hydrogen-bonding pattern differs from those reported for the previous polymorphs.

Related literature

For the biological activity of gallic acid, see: Lu et al. (2006 ▶); Madlener et al. (2007 ▶). For the previously reproted polymorphs, see: Jiang et al. (2000 ▶); Okabe et al. (2001 ▶). For a related structure, see: Genç et al. (2004 ▶).

Experimental

Crystal data

C₇H₆O₅·H₂O
M _r = 188.13
Monoclinic,
a = 9.7943 (7) Å
b = 3.6122 (2) Å
c = 21.5905 (15) Å
β = 91.268 (6)°
V = 763.66 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.15 mm⁻¹
T = 296 K
0.61 × 0.28 × 0.09 mm

Data collection

Stoe IPDS 2 diffractometer
Absorption correction: integration (X-RED32; Stoe & Cie, 2002 ▶) T _min = 0.948, T _max = 0.986
4558 measured reflections
1502 independent reflections
1262 reflections with I > 2σ(I)
R _int = 0.042

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.104
S = 1.04
1502 reflections
127 parameters
3 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.15 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2002 ▶); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002 ▶); program(s) used to solve structure: WinGX (Farrugia, 1997 ▶) and SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811018848/bx2352sup1.cif

e-67-o1509-sup1.cif^{(14.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811018848/bx2352Isup2.hkl

e-67-o1509-Isup2.hkl^{(72.6KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811018848/bx2352Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H3⋯O3	0.82	2.26	2.7006 (18)	114
O5—H6⋯O6	0.82	1.85	2.6542 (17)	167
O1—H2⋯O6ⁱ	0.82	2.03	2.7539 (19)	147
O2—H3⋯O3ⁱⁱ	0.82	2.52	3.1721 (19)	137
O3—H4⋯O4ⁱⁱⁱ	0.82	1.94	2.7154 (19)	158
O6—H6A⋯O2^iv	0.83 (2)	2.03 (2)	2.8237 (19)	161 (3)
O6—H6B⋯O1^v	0.82 (2)	2.00 (2)	2.814 (2)	171 (5)

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) .

Table 2. Other crystal structures of gallic acid monohydrate (Å, °).

	1	2
Unit-cell parameters	a = 5.794 (4)	a = 14.15 (1)
	b = 4.719 (5)	b = 3.622 (9)
	c = 28.688 (5)	c = 15.028 (10)
	β = 95.08 (3)	β = 97.52 (7)
	V = 781.4 (3)	V = 764 (1)
Space group	Monoclinic, P2₁/c	Monoclinic, P2/n
Reference	Jiang et al. (2000 ▶)	Okabe et al. (2001 ▶)

Open in a new tab

Acknowledgments

The authors thank the Ondokuz Mayıs University Research Fund for financial support of this project (project No. PYO.FEN.1904.09.006).

supplementary crystallographic information

Comment

Gallic acid and its derivatives are a group of naturally occurring polyphenol antioxidants which have recently been shown to have potential healty effects as an excellent free radical scavenger (Lu et al., 2006). In adition, gallic acid block DNA synthesis in leukemia cells (Madlener et al., 2007). Up to now, the different crystal structure of gallic acid monohidrate form have been reported by (Jiang et al., 2000; Okabe et al., 2001). The unit-cell parameters belong to these crystal structures have given at Table 2.

We report here the crystal structure of the title compound, C₇H₆O₅.H₂O. The asymmetric unit of title compound, C₇H₆O₅.H₂O, consists of one 3,4,5-trihydroxybenzoic acid molecule and one water molecule (Fig. 1). The C—C bond distances range from 1.378 (2) Å to 1.480 (2) Å. The longest C—C bond distance is between C6 and C7 with 1.480 Å. The C—O bond distance are range from 1.212 (2) Å to 1.3723 (19) Å. The shortest C—O bond distance is between C7 and O4 with 1.212 (2) Å. The C—O bond distance for different crystal structure was given 1.359 (2) Å by (Genç et al., 2004).

The crystal structure has two intramolecular hydrogen bonds and five intermolecular hydrogen bonds (Table 1). The O2—H3···O3 and O5—H6···O6 hydrogen bonds present in the asymmetric unit. In the crystal structure, the gallic acid molecules and water molecules are linked by the O6—H6A···O2, O6—H6B···O1, O5—H6···O6 and O1—H2···O6 hydrogen bonds. While the C—H···O hydrogen bond is present in crystal structure reported by (Jiang et al., 2000), there isn't present in our crystal structure. The via hydrogen atom of water molecule makes bifurcated hydrogen bond in crystal structure reported by (Jiang et al., 2000),but this kind hydrogen bond is not present in our crystal structure. In crystal structure reported by (Okabe et al., 2001), the hydroxyl groups make two intramolecular hydrogen bonds.

The torsion angles at ring belong to gallic acid molecule are range from 0.0 (3)° to 1.9 (3)°. Therefore, the gallic acid molecule close to planar. The tosion angles for the C2—C1—C6—C7 and C4—C5—C6—C7 are 179.51 (16)° and -179.08 (17)°, respectively. The O4—C7—O5 angle is 122.82 (15)°.

Experimental

A hot solution (60 °C) of gallic acid (0.002 mol, 0.340 g) in distilled water (approximately 20 ml) was gradually added to a hot stirring solution of magnesium sulfate heptahydrate (MgSO₄.7H₂O) (0.001 mol, 0.246 g) in distilled water (approximately 20 ml). The obtained mixture was stirred on a hot plate with slow evaporation to 30 ml at 60° C. The mixture was left for crystallization and in a few days, the crystals were obtained by slow evaporation from the solution at room temperature.