Methyl gallate

Bebout, D.; Pagola, S.

doi:10.1107/S1600536809001123

organic compounds

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ISSN: 2056-9890

Volume 65| Part 2| February 2009| Pages o317-o318

doi:10.1107/S1600536809001123

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Methyl gallate

Deborah Bebout ^a ^* and Silvina Pagola ^b

^aDepartment of Chemistry, College of William and Mary, PO Box 8795, Williamsburg, VA 23187-8795, USA, and ^bDepartment of Physics, College of William and Mary, PO Box 8795, Williamsburg, VA 23187-8795, USA
^*Correspondence e-mail: dcbebo@wm.edu

(Received 31 December 2008; accepted 9 January 2009; online 14 January 2009)

The crystal structure of the title compound (systematic name: methyl 3,4,5-trihydroxybenzoate), C₈H₈O₅, is composed of essentially planar molecules [maximum departures from the mean carbon and oxygen skeleton plane of 0.0348 (10) Å]. The H atoms of the three hydroxyl groups, which function as hydrogen-bond donors and acceptors simultaneously, are oriented in the same direction around the aromatic ring. In addition to two intramolecular hydrogen bonds, each molecule is hydrogen bonded to six others, creating a three-dimensional hydrogen-bonded network.

Related literature

For natural extracts containing gallic acid methyl ester, see: Saxena et al. (1994 ); Schmidt et al. (2003 ); Hawas (2007 ). For studies concerning antioxidant activity, see: Aruoma et al. (1993 ); Schmidt et al. (2003); Hawas (2007). For studies concerning anticancer properties, see: Fiuza et al. (2004 ) and for antimicrobial properties, see: Saxena et al. (1994); Landete et al. (2007 ). For cocrystals containing gallic acid methyl ester, see: Sekine et al. (2003 ); Martin et al. (1986 ). Similar gallate ester conformations are found in Parkin et al. (2002 ); Okabe & Kyoyama (2002a ); Nomura et al. (2000 ); Mizuguchi et al. (2005 ). For structures with similar hydroxyl arrangements, see: Hitachi et al. (2005 ); Okabe et al. (2001 ); Okabe & Kyoyama (2002b ). For a description of the Cambridge Structural Database, see: Allen (2002 ).

Experimental

Crystal data

C₈H₈O₅
M_r = 184.14
Monoclinic, P 2₁ /n
a = 7.6963 (2) Å
b = 9.9111 (2) Å
c = 10.5625 (2) Å
β = 95.9930 (10)°
V = 801.29 (3) Å³
Z = 4
Cu Kα radiation
μ = 1.12 mm⁻¹
T = 100 (2) K
0.31 × 0.23 × 0.21 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: numerical (SADABS; Sheldrick, 2004 ) T_min = 0.723, T_max = 0.799
8192 measured reflections
1352 independent reflections
1311 reflections with I > 2σ(I)
R_int = 0.034

Refinement

R[F² > 2σ(F²)] = 0.033
wR(F²) = 0.093
S = 0.69
1352 reflections
121 parameters
All H-atom parameters refined
Δρ_max = 0.23 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O4	0.84	2.25	2.7075 (13)	115
O4—H4⋯O5	0.84	2.29	2.7247 (12)	112
O4—H4⋯O1ⁱ	0.84	2.15	2.9470 (13)	159
O3—H3⋯O1ⁱⁱ	0.84	1.99	2.7007 (12)	142
O5—H5⋯O3ⁱⁱⁱ	0.84	1.86	2.6859 (12)	166
Symmetry codes: (i) $[x-{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (ii) $[-x-{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iii) $[x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker , 2004 ); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: WinGX (Farrugia, 1999 ); molecular graphics: ORTEP-3 (Farrugia, 1997 ) and Mercury (Macrae et al., 2006 ); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809001123/rz2286sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809001123/rz2286Isup2.hkl

checkCIF report

Comment top

Gallic acid methyl ester (I) is a polyphenolic compound present in grape seeds and other natural substrates (Saxena et al., 1994; Schmidt et al., 2003; Hawas, 2007). Like other polyphenols, I shows antioxidant activity (Aruoma et al., 1993; Schmidt et al., 2003; Hawas, 2007). Formerly used as an astringent and in opthalmology, its anticancer (Fiuza et al., 2004) and antimicrobial properties (Saxena et al., 1994; Landete et al., 2007) have also been studied. The molecular structure of I is shown below.

The molecular geometry is as expected from chemical bond rules (Figure 1) and it shows an almost planar conformation, with maximum departures from the mean carbon and oxygen skeleton plane of 0.0343 (9) and 0.0348 (10) Å for O4 and C8, respectively. The relative positions of the carbonyl and the three hydroxyls were also observed in a cocrystal of I and 5-chloro-2-methyl-4-isothiazoline-3-one (Sekine et al., 2003). Four other compounds containing a gallic acid ester moiety have crystallized in an analogous conformation (Parkin et al., 2002; Okabe & Kyoyama, 2002a; Nomura et al., 2000; Mizuguchi et al., 2005). Three other planar conformations of gallic acid esters are found in the Cambridge Structural Database (Allen, 2002). I has one of these other conformations in a cocrystal with caffeine (Martin et al., 1986).

Crystallized I has intra- and intermolecular hydrogen bonding. The hydroxyl H atoms bound to O3 and O4 (donors) form intramolecular hydrogen bonds to O4 and O5 (acceptors), respectively. This is shown in Figure 1. Similar hydroxyl arrangements have been reported in other gallic acid derivatives, such as gallate ester solvates (Hitachi et al., 2005), a gallic acid monohydrate polymorph (Okabe et al., 2001) and 2,3,4-trihydroxybenzophenone monohydrate (Okabe & Kyoyama, 2002b).

Gallic acid methyl ester forms a three-dimensional H-bonded network lacking significant aromatic ring stacking interactions. There is one molecule of I in the asymmetric unit. The H-bonded network is shown in Figure 2. Using the carbonyl ester oxygen O1 (acceptor) and the hydroxyl O3 and O4 (donors), each molecule is linked to another four through two O1···H3—O3, and two O1···H4—O4 H-bonds. These H-bonds are likely relatively weak due to the spacial orientation of the H atoms with respect to the lone electron pairs of O1. In addition, there are two other O5—H5···O3 H-bonds. The three hydroxyl sites are used as hydrogen bond donors and acceptors simultaneously. In the ester group, only the carbonyl oxygen is used as an H-bond acceptor.

Related literature top

For natural extracts containing gallic acid methyl ester, see: Saxena et al. (1994); Schmidt et al. (2003); Hawas (2007). For studies concerning antioxidant activity, see: Aruoma et al. (1993); Schmidt et al. (2003); Hawas (2007). For studies concerning anticancer properties, see: Fiuza et al. (2004) and for antimicrobial properties, see: Saxena et al. (1994); Landete et al. (2007). For cocrystals containing gallic acid methyl ester, see: Sekine et al. (2003); Martin et al. (1986). Similar gallate ester conformations are found in Parkin et al. (2002); Okabe & Kyoyama (2002a); Nomura et al. (2000); Mizuguchi et al. (2005). For structures with similar hydroxyl arrangements, see: Hitachi et al. (2005); Okabe et al. (2001); Okabe & Kyoyama (2002b). For a description of the Cambridge Structural Database, see: Allen (2002).

Experimental top

Gallic acid methyl ester was commercially obtained from Sigma-Aldrich (98% purity) and used as received. The crystal structure determination was carried out from a crystal with rhombic prismatic habit selected from the powder.

Computing details top

Data collection: APEX2 (Bruker , 2004); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: WinGX (Farrugia, 1999); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. Thermal ellipsoid plot of gallic acid methyl ester with the atomic numbering scheme. Non-H atoms are represented at 50% probability level. Intramolecular hydrogen bonds are shown with dashed lines.
	Fig. 2. The packing of gallic acid methyl ester molecules along the a-axis showing the unit cell and the hydrogen bonded network formed (dashed lines). Symmetry codes: (i) x,y,z; (ii) 1/2 + x, 1.5 - y, -1/2 + z; (iii) -1/2 + x, 1.5 - y, 1/2 + z; (iv) -1/2 + x,1.5 - y, -1/2 + z; (v) -1/2 - x, -1/2 + y, 1.5 - z; (vi) 1/2 + x, 1.5 - y, 1/2 + z; (vii) -1/2 - x, 1/2 + y, 1.5 - z.

methyl 3,4,5-trihydroxybenzoate top

Crystal data top

C₈H₈O₅	F(000) = 384
M_r = 184.14	D_x = 1.526 Mg m⁻³
Monoclinic, P2₁/n	Melting point: 474 K
Hall symbol: -P 2yn	Cu Kα radiation, λ = 1.54178 Å
a = 7.6963 (2) Å	Cell parameters from 1352 reflections
b = 9.9111 (2) Å	θ = 6.1–67.0°
c = 10.5625 (2) Å	µ = 1.12 mm⁻¹
β = 95.993 (1)°	T = 100 K
V = 801.29 (3) Å³	Rhombic prism, colourless
Z = 4	0.31 × 0.23 × 0.21 mm

Data collection top

Bruker SMART APEXII CCD diffractometer	1352 independent reflections
Radiation source: fine-focus sealed tube	1311 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.034
ω and ψ scans	θ_max = 67.0°, θ_min = 6.1°
Absorption correction: numerical (SADABS; Sheldrick, 2004)	h = −8→9
T_min = 0.723, T_max = 0.799	k = −11→11
8192 measured reflections	l = −12→12

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.033	Hydrogen site location: difference Fourier map
wR(F²) = 0.093	All H-atom parameters refined
S = 0.69	w = 1/[σ²(F_o²) + (0.0834P)² + 0.9466P] where P = (F_o² + 2F_c²)/3
1352 reflections	(Δ/σ)_max = 0.004
121 parameters	Δρ_max = 0.23 e Å⁻³
0 restraints	Δρ_min = −0.20 e Å⁻³
32 constraints

Crystal data top

C₈H₈O₅	V = 801.29 (3) Å³
M_r = 184.14	Z = 4
Monoclinic, P2₁/n	Cu Kα radiation
a = 7.6963 (2) Å	µ = 1.12 mm⁻¹
b = 9.9111 (2) Å	T = 100 K
c = 10.5625 (2) Å	0.31 × 0.23 × 0.21 mm
β = 95.993 (1)°

Data collection top

Bruker SMART APEXII CCD diffractometer	1352 independent reflections
Absorption correction: numerical (SADABS; Sheldrick, 2004)	1311 reflections with I > 2σ(I)
T_min = 0.723, T_max = 0.799	R_int = 0.034
8192 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.033	0 restraints
wR(F²) = 0.093	All H-atom parameters refined
S = 0.69	Δρ_max = 0.23 e Å⁻³
1352 reflections	Δρ_min = −0.20 e Å⁻³
121 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.14003 (11)	1.05605 (9)	0.77633 (8)	0.0145 (2)
O2	0.29090 (12)	0.99023 (9)	0.61631 (8)	0.0156 (3)
O3	−0.38148 (12)	0.74067 (10)	0.72722 (9)	0.0189 (3)
H3	−0.4389	0.6742	0.6963	0.028*
O4	−0.33530 (12)	0.58249 (9)	0.52444 (9)	0.0167 (2)
H4	−0.314	0.5462	0.4559	0.025*
O5	−0.05442 (13)	0.61740 (10)	0.39075 (9)	0.0185 (3)
H5	0.0127	0.6524	0.3422	0.028*
C7	0.15489 (17)	0.98352 (13)	0.68447 (12)	0.0121 (3)
C1	0.02736 (17)	0.87858 (13)	0.63777 (12)	0.0126 (3)
C2	−0.11958 (17)	0.85957 (13)	0.70290 (12)	0.0126 (3)
H2	−0.1378	0.9145	0.774	0.015*
C3	−0.23803 (17)	0.75983 (13)	0.66260 (12)	0.0129 (3)
C4	−0.21306 (17)	0.67861 (13)	0.55808 (12)	0.0129 (3)
C5	−0.06683 (17)	0.69987 (13)	0.49284 (12)	0.0134 (3)
C6	0.05370 (16)	0.79838 (13)	0.53249 (12)	0.0134 (3)
H6	0.1539	0.8116	0.4885	0.016*
C8	0.42258 (18)	1.09026 (14)	0.65644 (13)	0.0182 (3)
H8A	0.5161	1.0867	0.6003	0.027*
H8B	0.4712	1.0715	0.7441	0.027*
H8C	0.3695	1.1802	0.6521	0.027*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0147 (5)	0.0147 (5)	0.0141 (5)	0.0011 (4)	0.0010 (4)	−0.0023 (4)
O2	0.0135 (5)	0.0186 (5)	0.0153 (5)	−0.0048 (4)	0.0040 (4)	−0.0030 (4)
O3	0.0171 (5)	0.0206 (5)	0.0209 (5)	−0.0067 (4)	0.0108 (4)	−0.0070 (4)
O4	0.0188 (5)	0.0180 (5)	0.0141 (5)	−0.0071 (4)	0.0058 (4)	−0.0043 (4)
O5	0.0237 (5)	0.0196 (5)	0.0140 (5)	−0.0080 (4)	0.0103 (4)	−0.0057 (4)
C1	0.0135 (6)	0.0127 (6)	0.0114 (6)	0.0019 (5)	0.0004 (5)	0.0028 (5)
C2	0.0147 (7)	0.0130 (6)	0.0104 (6)	0.0023 (5)	0.0021 (5)	−0.0002 (5)
C3	0.0127 (6)	0.0147 (6)	0.0120 (6)	0.0012 (5)	0.0041 (5)	0.0025 (5)
C4	0.0137 (6)	0.0123 (6)	0.0124 (6)	−0.0012 (5)	0.0000 (5)	0.0022 (5)
C5	0.0176 (7)	0.0129 (6)	0.0100 (6)	0.0012 (5)	0.0032 (5)	0.0002 (5)
C6	0.0127 (6)	0.0159 (7)	0.0121 (6)	0.0004 (5)	0.0040 (5)	0.0024 (5)
C7	0.0129 (7)	0.0122 (6)	0.0111 (6)	0.0037 (5)	0.0006 (5)	0.0030 (5)
C8	0.0157 (7)	0.0203 (7)	0.0185 (7)	−0.0071 (5)	0.0015 (6)	−0.0010 (5)

Geometric parameters (Å, º) top

O1—C7	1.2225 (16)	C1—C6	1.3988 (19)
O2—C7	1.3327 (15)	C2—C3	1.3815 (18)
O2—C8	1.4491 (16)	C2—H2	0.95
O3—C3	1.3705 (15)	C3—C4	1.3957 (18)
O3—H3	0.84	C4—C5	1.3956 (18)
O4—C4	1.3598 (16)	C5—C6	1.3813 (18)
O4—H4	0.84	C6—H6	0.95
O5—C5	1.3644 (16)	C8—H8A	0.98
O5—H5	0.84	C8—H8B	0.98
C7—C1	1.4790 (19)	C8—H8C	0.98
C1—C2	1.3965 (17)

C7—O2—C8	116.16 (10)	O4—C4—C5	123.25 (11)
C3—O3—H3	109.5	O4—C4—C3	117.52 (11)
C4—O4—H4	109.5	C5—C4—C3	119.22 (12)
C5—O5—H5	109.5	O5—C5—C6	124.25 (11)
O1—C7—O2	122.91 (12)	O5—C5—C4	115.24 (12)
O1—C7—C1	124.36 (11)	C6—C5—C4	120.51 (11)
O2—C7—C1	112.72 (11)	C5—C6—C1	119.62 (12)
C2—C1—C6	120.47 (12)	C5—C6—H6	120.2
C2—C1—C7	118.29 (11)	C1—C6—H6	120.2
C6—C1—C7	121.24 (12)	O2—C8—H8A	109.5
C3—C2—C1	119.15 (12)	O2—C8—H8B	109.5
C3—C2—H2	120.4	H8A—C8—H8B	109.5
C1—C2—H2	120.4	O2—C8—H8C	109.5
O3—C3—C2	119.06 (11)	H8A—C8—H8C	109.5
O3—C3—C4	119.91 (12)	H8B—C8—H8C	109.5
C2—C3—C4	121.03 (12)

C8—O2—C7—O1	−0.42 (18)	C2—C3—C4—O4	179.88 (11)
C8—O2—C7—C1	−179.68 (10)	O3—C3—C4—C5	179.65 (11)
O1—C7—C1—C2	−0.53 (19)	C2—C3—C4—C5	−0.7 (2)
O2—C7—C1—C2	178.71 (11)	O4—C4—C5—O5	0.45 (19)
O1—C7—C1—C6	−179.44 (12)	C3—C4—C5—O5	−178.97 (11)
O2—C7—C1—C6	−0.19 (17)	O4—C4—C5—C6	−179.37 (11)
C6—C1—C2—C3	0.47 (19)	C3—C4—C5—C6	1.21 (19)
C7—C1—C2—C3	−178.44 (11)	O5—C5—C6—C1	179.28 (12)
C1—C2—C3—O3	179.52 (11)	C4—C5—C6—C1	−0.92 (19)
C1—C2—C3—C4	−0.17 (19)	C2—C1—C6—C5	0.07 (19)
O3—C3—C4—O4	0.19 (18)	C7—C1—C6—C5	178.95 (11)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O4	0.84	2.25	2.7075 (13)	115
O4—H4···O5	0.84	2.29	2.7247 (12)	112
O4—H4···O1ⁱ	0.84	2.15	2.9470 (13)	159
O3—H3···O1ⁱⁱ	0.84	1.99	2.7007 (12)	142
O5—H5···O3ⁱⁱⁱ	0.84	1.86	2.6859 (12)	166

Symmetry codes: (i) x−1/2, −y+3/2, z−1/2; (ii) −x−1/2, y−1/2, −z+3/2; (iii) x+1/2, −y+3/2, z−1/2.

Experimental details

Crystal data
Chemical formula	C₈H₈O₅
M_r	184.14
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	7.6963 (2), 9.9111 (2), 10.5625 (2)
β (°)	95.993 (1)
V (Å³)	801.29 (3)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	1.12
Crystal size (mm)	0.31 × 0.23 × 0.21

Data collection
Diffractometer	Bruker SMART APEXII CCD diffractometer
Absorption correction	Numerical (SADABS; Sheldrick, 2004)
T_min, T_max	0.723, 0.799
No. of measured, independent and observed [I > 2σ(I)] reflections	8192, 1352, 1311
R_int	0.034
(sin θ/λ)_max (Å⁻¹)	0.597

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.093, 0.69
No. of reflections	1352
No. of parameters	121
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.23, −0.20

Computer programs: APEX2 (Bruker , 2004), SAINT-Plus (Bruker, 2004), SHELXS97 (Sheldrick, 2008), WinGX (Farrugia, 1999), ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006), SHELXL97 (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O4	0.84	2.25	2.7075 (13)	114.5
O4—H4···O5	0.84	2.29	2.7247 (12)	112.4
O4—H4···O1ⁱ	0.84	2.15	2.9470 (13)	159.2
O3—H3···O1ⁱⁱ	0.84	1.99	2.7007 (12)	142.4
O5—H5···O3ⁱⁱⁱ	0.84	1.86	2.6859 (12)	166.4

Symmetry codes: (i) x−1/2, −y+3/2, z−1/2; (ii) −x−1/2, y−1/2, −z+3/2; (iii) x+1/2, −y+3/2, z−1/2.

Acknowledgements

We are indebted to the NSF (CHE-0443345) and The College of William and Mary for the purchase of X-ray equipment. This work was supported in part by the US National Science Foundation (CHE-0315934). Any opinions, findings and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation. SP gratefully acknowledges the Physics Department of the College of William and Mary for funding and ICDD GIA 08–04.

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Volume 65| Part 2| February 2009| Pages o317-o318

doi:10.1107/S1600536809001123

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