3,4,5-Trihy­droxy­benzoic acid

Namon Hirun; Saowanit Saithong; Chaveng Pakawatchai; Vimon Tantishaiyakul

doi:10.1107/S1600536811007471

. 2011 Mar 5;67(Pt 4):o787. doi: 10.1107/S1600536811007471

3,4,5-Trihydroxybenzoic acid

Namon Hirun ^a, Saowanit Saithong ^b, Chaveng Pakawatchai ^b, Vimon Tantishaiyakul ^a,^*

PMCID: PMC3099763 PMID: 21754078

Abstract

In the title compound, C₇H₆O₅, the three hydroxy groups on the ring are oriented in the same direction. There are two intramolecular O—H⋯O hydrogen bonds in the ring. In the crystal, there are several intermolecular O—H⋯O hydrogen bonds and a short contact of 2.7150 (18) Å between the O atoms of the para-OH groups of adjacent molecules.

Related literature

For the biological activity of the title compound, see: Gomes et al. (2003 ▶); Priscilla & Prince (2009 ▶); Lu et al. (2010 ▶). For the structure of gallic acid monohydrate, see: Okabe et al. (2001 ▶); Jiang et al. (2000 ▶); Billes et al. (2007 ▶).

Experimental

Crystal data

C₇H₆O₅
M _r = 170.12
Monoclinic,
a = 25.629 (2) Å
b = 4.9211 (4) Å
c = 11.2217 (9) Å
β = 106.251 (1)°
V = 1358.77 (19) Å³
Z = 8
Mo Kα radiation
μ = 0.15 mm⁻¹
T = 293 K
0.30 × 0.19 × 0.11 mm

Data collection

Bruker APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2003 ▶) T _min = 0.916, T _max = 1.000
7171 measured reflections
1254 independent reflections
1172 reflections with I > 2s(I)
R _int = 0.022

Refinement

R[F ² > 2σ(F ²)] = 0.032
wR(F ²) = 0.091
S = 1.06
1254 reflections
121 parameters
4 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: SMART (Bruker, 1998 ▶); cell refinement: SAINT (Bruker, 2003 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶) and Mercury (Macrae et al., 2008) ▶; software used to prepare material for publication: SHELXL97 and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811007471/fj2397sup1.cif

e-67-0o787-sup1.cif^{(14.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811007471/fj2397Isup2.hkl

e-67-0o787-Isup2.hkl^{(62.1KB, hkl)}

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—H2⋯O1	0.82 (1)	2.19 (2)	2.6625 (14)	117 (1)
O3—H3⋯O2	0.82 (1)	2.35 (2)	2.7464 (14)	110 (1)
O1—H1⋯O5ⁱ	0.84 (1)	1.89 (2)	2.7324 (13)	176 (2)
O3—H3⋯O3ⁱⁱ	0.82 (1)	2.04 (2)	2.8167 (9)	157 (2)
O4—H4⋯O5ⁱⁱⁱ	0.85 (2)	1.81 (2)	2.6570 (13)	175 (2)

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

Acknowledgments

This work was supported by the Thailand Research Fund through the Royal Golden Jubilee PhD Program under grant No. PHD/0259/2549, the Prince of Songkla University under grant No. PHA520036S and the National Research University Project of Thailand’s Office of the Higher Education Commission.

supplementary crystallographic information

Comment

Gallic acid, 3,4,5-trihydroxybenzoic acid, has been reported to have various biological activities such as antioxidant, antimutagenic, anticarcinogenic, antihyperglycemic and cardioprotective effects (Gomes et al., 2003; Priscilla & Prince, 2009; Lu et al., 2010). It has been shown that the activity of polyphenolic compounds, including gallic acid, is dependent on their structural characteristics (Gomes et al., 2003). Thus, the investigation of its crystal structure is important for a better understanding of its biological functions. Recently, different crystal structures of gallic acid monohydrate have been reported (Jiang et al., 2000; Okabe et al., 2001; Billes et al., 2007). Here, for the first time, the crystal structure of anhydrous gallic acid (I) was determined. The molecular structure of I is planar [Fig.1]. All the H atoms of the three hydroxy groups are oriented in the same direction.

The intra-hydrogen bonds are found between these hydroxy groups, O2···O1 = 2.6625 (14) and O3···O2 = 2.7464 (14)Å [Table.1]. This agrees with the report of Okabe et al. (2001). However, this orientation is inconsistent with those described by Billes et al. (2007) and Jiang et al. (2000), in which one H atom of the hydroxy group is oriented in the opposite direction to the others. The dissimilarity between I and the gallic acid monohydrate structure reported by Okabe is the different orientation of their carboxyl groups in relation to the direction of the three hydroxy groups.

The inter-hydrogen bonds in the crystal packing of I are found between oxygen atoms,O3···O3ⁱⁱ [2.8167 (9) Å, symmetry code (ii): 1/2 - x, y + 1/2 - z - 1/2], O1···O5ⁱ [2.7324 (13) Å, symmetry code (i): x, -y + 1, z + 1/2] and O4···O5ⁱⁱⁱ [2.6570 (13) Å, symmetry code (iii): -x + 1, -y, -z] [Table 1]. Moreover, the short contact between the oxygen of the hydroxy groups of the adjacent molecule is observed, O2···O2^vi [2.7150 (18) Å, symmetry code (vi): 1/2 - x, 2.5 - y, -z]. All intra- and intermolecular interactions including short contacts are depicted in Fig. 2 and the packing interactions as plotted down the b axis are shown in Fig. 3.

Experimental

Gallic acid monohydrate was obtained from Fluka Chemie GmbH (Buchs, Switzerland). The anhydrous gallic acid crystals for this X-ray structure study were obtained by dissolving gallic acid monohydrate in diethyl ether followed by a slow evaporation of the solvent.