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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 67| Part 2| February 2011| Pages o316-o317
doi:10.1107/S1600536811000262

Gallic acid

Jianping Zhao,a Ikhlas A. Khana,b and Frank R. Fronczekc*

aNational Center for Natural Products Research, RIPS, School of Pharmacy, University of Mississippi, University, MS 38677, USA, bDepartment of Pharmacognosy, RIPS, School of Pharmacy, University of Mississippi, University, MS 38677, USA, and cDepartment of Chemistry, Louisiana State University, Baton Rouge, LA 70803-1804, USA
*Correspondence e-mail: ffroncz@lsu.edu

(Received 3 December 2010; accepted 4 January 2011; online 12 January 2011)

Anhydrous 3,4,5-trihy­droxy­benzoic acid, C7H6O5, is essentially planar, with its non-H atoms exhibiting mean and maximum deviations from coplanarity of 0.014 and 0.0377 (5) Å, respectively. The C—C—C—OH torsion angle about the bond linking the carboxyl group to the benzene ring is −0.33 (10)°. In the crystal, the –COOH groups form centrosymmetric hydrogen-bonded cyclic dimers [graph set R22(8)] and the phenolic –OH groups participate in both intra- and inter­molecular hydrogen bonds, forming a three-dimensional network structure.

Related literature

For distribution of gallic acid in plants and for biological studies, see: Fiuza et al. (2004[Fiuza, S. M., Gomes, C., Teixeira, L. J., Girão da Cruz, M. T., Cordeiro, M. N. D. S., Milhazes, N., Borges, F. & Marques, M. P. M. (2004). Bioorg. Med. Chem. 12, 3581-3589.]); Ow & Stupans (2003[Ow, Y. Y. & Stupans, I. (2003). Curr. Drug Metab. 4, 241-248.]); Hemingway et al. (1999[Hemingway, R. W., Gross, G. G. & Yoshida, T. (1999). Plant Polyphenols: Chemistry and Biology, pp. 495-505. New York: Plenum Press.]). For NMR data, see: Lu et al. (2007[Lu, J. J., Wei, Y. & Yuan, Q. P. (2007). Sep. Purif. Technol. 55, 40-43.]). For graph sets, see: Etter (1990[Etter, M. C. (1990). Acc. Chem. Res. 23, 120-126.]); Zaheer et al. (2010[Zaheer, S., Lenin, R., Thangavel, S., Ashok, V., Viswanathan, M. & Muthuswamy, B. (2010). Phytother. Res. Suppl. 1, S83-S94.]). For related structures, see: Jiang et al. (2000[Jiang, R.-W., Ming, D.-S., But, P. P. H. & Mak, T. C. W. (2000). Acta Cryst. C56, 594-595.]); Okabe et al. (2001[Okabe, N., Kyoyama, H. & Suzuki, M. (2001). Acta Cryst. E57, o764-o766.]); Billes et al. (2007[Billes, F., Mohammed-Ziegler, I. & Bombicz, P. (2007). Vibr. Spectrosc. 43, 193-202.]); Qadeer et al. (2007[Qadeer, G., Rama, N. H., Taş, M., Yeşilel, O. Z. & Wong, W.-Y. (2007). Acta Cryst. E63, o3456.]).

[Scheme 1]

Experimental

Crystal data

  • C7H6O5

  • Mr = 170.12

  • Monoclinic, C 2/c

  • a = 25.690 (4) Å

  • b = 4.8946 (5) Å

  • c = 11.097 (2) Å

  • β = 105.746 (6)°

  • V = 1343.0 (4) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.15 mm−1

  • T = 90 K

  • 0.25 × 0.23 × 0.15 mm
Data collection

  • Nonius KappaCCD diffractometer with an Oxford Cryosystems Cryostream cooler

  • 17352 measured reflections

  • 2674 independent reflections

  • 2391 reflections with I > 2σ(I)

  • Rint = 0.016
Refinement

  • R[F2 > 2σ(F2)] = 0.034

  • wR(F2) = 0.103

  • S = 1.06

  • 2674 reflections

  • 122 parameters

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.62 e Å−3

  • Δρmin = −0.31 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
O2—H20⋯O1i 0.910 (15) 1.730 (15) 2.6384 (8) 175.6 (13)
O3—H30⋯O3ii 0.881 (14) 1.964 (14) 2.7943 (5) 156.6 (12)
O3—H30⋯O4 0.881 (14) 2.345 (13) 2.7579 (9) 108.8 (10)
O4—H40⋯O5 0.838 (14) 2.191 (13) 2.6688 (8) 116.1 (11)
O5—H50⋯O1iii 0.893 (14) 1.828 (14) 2.7200 (8) 178.6 (14)
Symmetry codes: (i) -x+1, -y+2, -z+1; (ii) [-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]; (iii) [x, -y+1, z+{\script{1\over 2}}].

Data collection: COLLECT (Nonius, 2000[Nonius (2000). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: DENZO (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]) and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1999[Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811000262/zs2084sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811000262/zs2084Isup2.hkl

checkCIF report


Comment top

Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is found widely distributed in plants. It occurs as a free molecule or as one of the chemical components in tannin (Hemingway et al., 1999). GA and its derivatives are also present in gallnuts, oak bark, sumac, grapes, and tea leaves as one of the main phenolic components (Ow & Stupans, 2003). Biological studies showed that GA has various properties, including anti-fungal, anti-viral, antioxidant, and anti-cancer activities (Fiuza et al., 2004; Zaheer et al., 2010). GA is also employed as a source material for inks and paints, and as an antioxidant in food, in cosmetics and in the pharmaceutical industry.

While the crystal structures of two polymorphs of gallic acid monohydrate have been reported (P21/c and P2/n) (Jiang et al., 2000; Okabe et al., 2001; Billes et al., 2007), the structure of the unsolvated compound has not appeared. Our isolation of GA from plant material of Galega officinalis yielded anhydrous crystals when crystallized from methanol/chloroform, and allowed determination of its structure. The molecule of GA (Fig. 1) is essentially planar, with mean and maximum deviations from coplanarity of 0.014 Å and 0.0377 (5) Å respectively. This is slightly more planar than that found for the monohydrate, in which the carboxyl group twists out of the phenyl plane by 2.9° (Jiang et al., 2000).

The carboxyl group forms normal centrosymmetric hydrogen-bonded cyclic dimers [graph set R22(8) (Etter, 1990)] as shown in Fig. 2. The phenolic hydrogen atoms all lie nearly in the plane of the phenyl ring, with C—C—O—H torsion angle values in the range 0.4–17.5°. This is similar to those found in the P21/c polymorph of the monohydrate (Jiang et al., 2000), in which the torsion angle range is 5.9–24.5°. There is some question about the positions of these H atoms in the P2/n polymorph of the monohydrate, as one determination (Okabe et al., 2001) agrees with what we see in the anhydrous structure, while the other report of the P2/n polymorph (Billes et al., 2007) has one OH group nearly orthogonal to the phenyl ring, with a C—C—O—H torsion angle of 92°. It appears that the Okabe et al. H position is more likely to be correct, since it fits the hydrogen-bonding pattern more sensibly, and the Billes et al. determination also reports a clearly misplaced water H atom, with an O—H distance of 1.40 Å and an unlikely H—O—H angle of 67.5°.

The phenolic OH groups in the title compound form intramolecular (O4), intermolecular (O5) and bifurcated intramolecular/intermolecular (O3) hydrogen bonds (Table 1). The intramolecular hydrogen bonds, forming 5-membered rings are necessarily quite nonlinear, with an O—H···O angle of 108.8 (10)° for the O3 donor and 116.1 (11)° for the O4 donor. The intermolecular component of the bifurcated intramolecular/intermolecular hydrogen bond involving O3 forms C11(2) chains (Etter, 1990) in the [010] direction. The OH group O5 is involved in C11(7) chains in the [001] direction.

Related literature top

For distribution of gallic acid in plants and for biological studies, see: Fiuza et al. (2004); Ow & Stupans (2003); Hemingway et al. (1999). For NMR data, see: Lu et al. (2007). For graph sets, see: Etter (1990); Zaheer et al. (2010). For related structures, see: Jiang et al. (2000); Okabe et al. (2001); Billes et al. (2007); Qadeer et al. (2007).

Experimental top

Gallic acid was isolated from Galega officinalis L. Fam. (Fabaceae). The dried and ground plant material of G. officinalis (1.5 kg) was extracted with methanol to yield 182 g of MeOH extract. The extract was subjected to flash column chromatography over silica gel (2 kg) and eluted with CHCl3—MeOH and CHCl3—MeOH-H2O of increasing polarity to afford 50 fractions (1–50). Gallic acid (683 mg) was obtained from the fraction 30 (3.66 g) by using a Sephadex LH-20 column for purification. The crystals of gallic acid were formed as plates from the methanol/chloroform solution. The High resolution mass analysis (HR-ESI-MS) of the isolated gallic acid, which was conducted on an Agilent Series 1100 SL mass spectrometer, provided the molecular formula as C7H6O5. The NMR data, which were recorded at 400 (1H) and 100 (13C) MHz using a Bruker Avance DRX400 NMR spectrometer, were in agreement with those reported in the literature (Lu et al., 2007).

Refinement top

H atoms on C were placed in idealized positions with C—H distances 0.98–0.99 Å and thereafter treated as riding. Coordinates of OH hydrogen atoms were refined. Uiso for H were assigned as 1.2Ueq of the attached atoms (1.5Ueq for OH). All peaks in the final difference map larger than 0.21 e Å-3 were located near bond centers.

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Molecular conformation and atom numbering scheme for the title compound with displacement elipsoids drawn at the 50% level.
[Figure 2] Fig. 2. The packing in the unit cell viewed down the approximate b axial direction, with H-bonds shown in blue.
3,4,5-trihydroxybenzoic acid top
Crystal data top
C7H6O5F(000) = 704
Mr = 170.12Dx = 1.683 Mg m−3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 2808 reflections
a = 25.690 (4) Åθ = 2.5–33.7°
b = 4.8946 (5) ŵ = 0.15 mm−1
c = 11.097 (2) ÅT = 90 K
β = 105.746 (6)°Plate fragment, colorless
V = 1343.0 (4) Å30.25 × 0.23 × 0.15 mm
Z = 8
Data collection top
Nonius KappaCCD
diffractometer with an Oxford Cryosystems Cryostream cooler		2391 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.016
Graphite monochromatorθmax = 33.7°, θmin = 3.3°
ω and ϕ scansh = −39→40
17352 measured reflectionsk = −7→6
2674 independent reflectionsl = −17→17
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.034H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.103 w = 1/[σ2(Fo2) + (0.0587P)2 + 0.8373P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max = 0.001
2674 reflectionsΔρmax = 0.62 e Å−3
122 parametersΔρmin = −0.31 e Å−3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0044 (13)
Crystal data top
C7H6O5V = 1343.0 (4) Å3
Mr = 170.12Z = 8
Monoclinic, C2/cMo Kα radiation
a = 25.690 (4) ŵ = 0.15 mm−1
b = 4.8946 (5) ÅT = 90 K
c = 11.097 (2) Å0.25 × 0.23 × 0.15 mm
β = 105.746 (6)°
Data collection top
Nonius KappaCCD
diffractometer with an Oxford Cryosystems Cryostream cooler		2391 reflections with I > 2σ(I)
17352 measured reflectionsRint = 0.016
2674 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0340 restraints
wR(F2) = 0.103H atoms treated by a mixture of independent and constrained refinement
S = 1.06Δρmax = 0.62 e Å−3
2674 reflectionsΔρmin = −0.31 e Å−3
122 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.44464 (2)0.87525 (12)0.40294 (5)0.01094 (12)
O20.48521 (2)0.73099 (12)0.59692 (5)0.01333 (13)
H200.5098 (6)0.863 (3)0.5937 (13)0.020*
O30.27635 (2)0.27737 (12)0.28219 (5)0.01114 (12)
H300.2590 (5)0.123 (3)0.2837 (12)0.017*
O40.28383 (2)−0.05022 (12)0.48841 (5)0.01200 (13)
H400.2916 (5)−0.133 (3)0.5572 (13)0.018*
O50.36851 (2)−0.02019 (12)0.69013 (5)0.01222 (12)
H500.3938 (5)0.025 (3)0.7598 (13)0.018*
C10.40393 (3)0.51466 (15)0.49199 (7)0.00865 (13)
C20.35992 (3)0.48758 (15)0.38610 (7)0.00907 (13)
H20.35730.59970.31480.011*
C30.32001 (3)0.29613 (15)0.38566 (6)0.00847 (13)
C40.32395 (3)0.13157 (14)0.49036 (6)0.00861 (13)
C50.36881 (3)0.15566 (15)0.59516 (6)0.00883 (13)
C60.40877 (3)0.34810 (15)0.59730 (6)0.00946 (13)
H60.43880.36660.66880.011*
C70.44573 (3)0.72128 (15)0.49266 (6)0.00906 (13)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0098 (2)0.0112 (2)0.0104 (2)−0.00298 (17)0.00042 (17)0.00155 (18)
O20.0101 (2)0.0151 (3)0.0115 (2)−0.00630 (19)−0.00259 (18)0.00275 (19)
O30.0078 (2)0.0101 (2)0.0120 (2)−0.00233 (17)−0.00328 (17)0.00127 (18)
O40.0094 (2)0.0120 (3)0.0133 (2)−0.00483 (18)0.00076 (18)0.00206 (18)
O50.0133 (2)0.0130 (3)0.0087 (2)−0.00419 (19)0.00019 (18)0.00260 (18)
C10.0072 (3)0.0085 (3)0.0094 (3)−0.0018 (2)0.0009 (2)−0.0001 (2)
C20.0077 (3)0.0091 (3)0.0093 (3)−0.0011 (2)0.0005 (2)0.0005 (2)
C30.0066 (2)0.0083 (3)0.0091 (3)−0.0002 (2)−0.0003 (2)0.0000 (2)
C40.0068 (3)0.0082 (3)0.0100 (3)−0.0014 (2)0.0010 (2)−0.0003 (2)
C50.0086 (3)0.0089 (3)0.0083 (3)−0.0009 (2)0.0012 (2)0.0003 (2)
C60.0079 (3)0.0102 (3)0.0090 (3)−0.0019 (2)0.0003 (2)−0.0001 (2)
C70.0075 (3)0.0091 (3)0.0096 (3)−0.0012 (2)0.0006 (2)−0.0007 (2)
Geometric parameters (Å, º) top
O1—C71.2429 (9)C1—C21.3984 (10)
O2—C71.3163 (9)C1—C61.4025 (10)
O2—H200.910 (15)C1—C71.4737 (10)
O3—C31.3732 (8)C2—C31.3880 (10)
O3—H300.881 (14)C2—H20.9500
O4—C41.3575 (9)C3—C41.3947 (10)
O4—H400.838 (14)C4—C51.4025 (9)
O5—C51.3624 (9)C5—C61.3885 (10)
O5—H500.893 (14)C6—H60.9500
C7—O2—H20111.7 (9)O4—C4—C3118.82 (6)
C3—O3—H30110.1 (9)O4—C4—C5121.19 (6)
C4—O4—H40108.0 (9)C3—C4—C5119.99 (6)
C5—O5—H50111.0 (9)O5—C5—C6125.08 (6)
C2—C1—C6120.91 (6)O5—C5—C4114.36 (6)
C2—C1—C7119.42 (6)C6—C5—C4120.56 (6)
C6—C1—C7119.67 (6)C5—C6—C1118.82 (6)
C3—C2—C1119.67 (7)C5—C6—H6120.6
C3—C2—H2120.2C1—C6—H6120.6
C1—C2—H2120.2O1—C7—O2121.78 (6)
O3—C3—C2118.88 (6)O1—C7—C1123.64 (6)
O3—C3—C4121.07 (6)O2—C7—C1114.57 (6)
C2—C3—C4120.02 (6)
C6—C1—C2—C30.95 (11)O4—C4—C5—C6−178.08 (7)
C7—C1—C2—C3−179.03 (6)C3—C4—C5—C61.92 (11)
C1—C2—C3—O3178.27 (6)O5—C5—C6—C1179.54 (7)
C1—C2—C3—C4−0.12 (11)C4—C5—C6—C1−1.09 (11)
O3—C3—C4—O40.35 (10)C2—C1—C6—C5−0.35 (11)
C2—C3—C4—O4178.70 (6)C7—C1—C6—C5179.64 (7)
O3—C3—C4—C5−179.65 (6)C2—C1—C7—O1−0.56 (11)
C2—C3—C4—C5−1.30 (11)C6—C1—C7—O1179.45 (7)
O4—C4—C5—O51.35 (10)C2—C1—C7—O2179.65 (6)
C3—C4—C5—O5−178.64 (6)C6—C1—C7—O2−0.33 (10)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H20···O1i0.910 (15)1.730 (15)2.6384 (8)175.6 (13)
O3—H30···O3ii0.881 (14)1.964 (14)2.7943 (5)156.6 (12)
O3—H30···O40.881 (14)2.345 (13)2.7579 (9)108.8 (10)
O4—H40···O50.838 (14)2.191 (13)2.6688 (8)116.1 (11)
O5—H50···O1iii0.893 (14)1.828 (14)2.7200 (8)178.6 (14)
Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) −x+1/2, y−1/2, −z+1/2; (iii) x, −y+1, z+1/2.

Experimental details

Crystal data
Chemical formulaC7H6O5
Mr170.12
Crystal system, space groupMonoclinic, C2/c
Temperature (K)90
a, b, c (Å)25.690 (4), 4.8946 (5), 11.097 (2)
β (°) 105.746 (6)
V (Å3)1343.0 (4)
Z8
Radiation typeMo Kα
µ (mm−1)0.15
Crystal size (mm)0.25 × 0.23 × 0.15
Data collection
DiffractometerNonius KappaCCD
diffractometer with an Oxford Cryosystems Cryostream cooler
Absorption correction–
No. of measured, independent and
observed [I > 2σ(I)] reflections		17352, 2674, 2391
Rint0.016
(sin θ/λ)max (Å−1)0.781
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.034, 0.103, 1.06
No. of reflections2674
No. of parameters122
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)0.62, −0.31

Computer programs: COLLECT (Nonius, 2000), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H20···O1i0.910 (15)1.730 (15)2.6384 (8)175.6 (13)
O3—H30···O3ii0.881 (14)1.964 (14)2.7943 (5)156.6 (12)
O3—H30···O40.881 (14)2.345 (13)2.7579 (9)108.8 (10)
O4—H40···O50.838 (14)2.191 (13)2.6688 (8)116.1 (11)
O5—H50···O1iii0.893 (14)1.828 (14)2.7200 (8)178.6 (14)
Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) −x+1/2, y−1/2, −z+1/2; (iii) x, −y+1, z+1/2.
 

Acknowledgements

The purchase of the diffractometer was made possible by grant No. LEQSF(1999–2000)-ENH-TR-13, administered by the Louisiana Board of Regents.

References

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 First citationBilles, F., Mohammed-Ziegler, I. & Bombicz, P. (2007). Vibr. Spectrosc. 43, 193–202.  Web of Science CSD CrossRef CAS Google Scholar
 First citationEtter, M. C. (1990). Acc. Chem. Res. 23, 120–126.  CrossRef CAS Web of Science Google Scholar
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ISSN: 2056-9890
Volume 67| Part 2| February 2011| Pages o316-o317
doi:10.1107/S1600536811000262
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