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Acta Crystallogr Sect E Struct Rep Online. 2010 December 1; 66(Pt 12): o3179.
Published online 2010 November 13. doi:  10.1107/S1600536810046441
PMCID: PMC3011420

Triethyl­ammonium 3,4-dihy­droxy­benzoate monohydrate

Abstract

In the structure of the title compound, C6H16N+·C7H5O4 ·H2O, O—H(...)O and N—H(...)O hydrogen bonds link the components into a three-dimensional array. The 3,4-dihy­droxy­benzoate anion is approximately planar, with a maximum deviation of 0.083 (2) Å.

Related literature

For protocatechuic acid (3,4-dihy­droxy­benzoic acid) and its pharmacological activity, see: An et al. (2006 [triangle]); Guan et al. (2006 [triangle]); Lin et al. (2009 [triangle]); Tseng et al. (1998 [triangle]); Yip et al. (2006 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o3179-scheme1.jpg

Experimental

Crystal data

  • C6H16N+·C7H5O4 ·H2O
  • M r = 273.32
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-o3179-efi1.jpg
  • a = 10.7163 (16) Å
  • b = 11.5973 (17) Å
  • c = 11.7690 (17) Å
  • V = 1462.7 (4) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 296 K
  • 0.30 × 0.28 × 0.28 mm

Data collection

  • Bruker APEXII area-detector diffractometer
  • 7531 measured reflections
  • 1519 independent reflections
  • 1211 reflections with I > 2σ(I)
  • R int = 0.043

Refinement

  • R[F 2 > 2σ(F 2)] = 0.038
  • wR(F 2) = 0.093
  • S = 1.04
  • 1519 reflections
  • 186 parameters
  • 3 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.20 e Å−3
  • Δρmin = −0.14 e Å−3

Data collection: APEX2 (Bruker, 2004 [triangle]); cell refinement: SAINT (Bruker, 2004 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXL97.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810046441/zl2325sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810046441/zl2325Isup2.hkl

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

Acknowledgments

The author acknowledges South China Normal University for supporting this work.

supplementary crystallographic information

Comment

Protocatechuic acid (3,4-dihydroxybenzoic acid) is one of the main secondary metabolites in the plant kingdom (Guan et al., 2006). Significantly, it has been found that protocatechuic acid and its derivatives possess diverse pharmacological activities such as antioxidant, antiapoptosis, anticarcinogen, anticoagulatory and antiinflammatory (An et al., 2006; Lin et al., 2009; Tseng et al., 1998; Yip et al., 2006). The molecular and crystal structure of the title compound, a triethylammonium of protocatechuic acid, is presented in this article.

In the asymmetric unit of the title compound, illustrated in Fig. 1, there are a triethylammonium cation, one singly deprotonated 3,4-dihydroxybenzoate anion and one water molecule. The 3,4-dihydroxybenzoate anion is approximately planar, with a maximum deviation of any non-H atom from its plane of 0.083 (2) Å for atom O1. The orientations of the three ethyl groups of the triethylammonium cation are different. Two of the ethyl substituents are rougly in plane with the nitrogen atom and the methylene carbon atoms. The torsion angles of these two groups against the N—H bond are -53.1 for C10—C11, and -61.8 for C12—C13. The third ethyl group, C8—C9, is rotated out of this plane and is pointing downward with respect to the N—H bond with a torsion angle of 175.4°. The water molecule forms two O—H···O hydrogen bonds with two 3,4-dihydroxybenzoate anions involving O1w—H1w···O3ii and O1w—H2w···O2i (see Table 1 for symmetry operators and bonding geometries). The hydroxy groups of the 3,4-dihydroxybenzoate anion form O—H···O hydrogen bonds to the carboxylate groups of two adjacent anions. The N1—H14···O2i hydrogen bond between the triethylammonium cation and the 3,4-dihydroxybenzoate anion is the main force influencing the orientation of the triethylammonium cation. These hydrogen bonds link the triethylammonium cations, 3,4-dihydroxybenzoate anions and water molecules into a three-dimensional array (Fig. 2).

Experimental

A solution of triethylamine (2 mmol in 0.5 ml water) was added dropwise to a solution of protocatechuic acid (2 mmol) in acetonitrile (15 ml), and the mixture was stirred for 30 min at room temperature. After several days colourless block-like crystals, suitable for X-ray diffraction analysis, were obtained by slow evaporation of the solution.

Refinement

H14 atom of the triethylammonium cation and H atoms of the water molecule were found from difference Fourier maps and refined isotropically with a restraint of N—H = 0.89 (2) Å, O—H = 0.86 (2) Å and Uiso(H) = 1.5 Ueq(N, O). All other H atoms were positioned geometrically and refined as riding, with O—H = 0.82 Å and C—H = 0.93, 0.96 or 0.97 Å, and with Uiso(H) = 1.2 or 1.5 Ueq(C, O).

Figures

Fig. 1.
The molecular structure showing the atomic-numbering scheme and displacement ellipsoids drawn at the 50% probability level.
Fig. 2.
The molecular packing showing the intermolecular hydrogen bonding interactions as broken lines.

Crystal data

C6H16N+·C7H5O4·H2OF(000) = 592
Mr = 273.32Dx = 1.241 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 1465 reflections
a = 10.7163 (16) Åθ = 2.5–21.3°
b = 11.5973 (17) ŵ = 0.10 mm1
c = 11.7690 (17) ÅT = 296 K
V = 1462.7 (4) Å3Block, colourless
Z = 40.30 × 0.28 × 0.28 mm

Data collection

Bruker APEXII area-detector diffractometer1211 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.043
graphiteθmax = 25.2°, θmin = 2.5°
[var phi] and ω scansh = −12→6
7531 measured reflectionsk = −13→13
1519 independent reflectionsl = −14→14

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.038Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.093H atoms treated by a mixture of independent and constrained refinement
S = 1.04w = 1/[σ2(Fo2) + (0.0404P)2 + 0.2897P] where P = (Fo2 + 2Fc2)/3
1519 reflections(Δ/σ)max < 0.001
186 parametersΔρmax = 0.20 e Å3
3 restraintsΔρmin = −0.14 e Å3

Special details

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)

xyzUiso*/Ueq
C10.9308 (3)0.5565 (2)0.8260 (2)0.0342 (6)
H10.95650.50650.76880.041*
C60.9902 (3)0.6627 (2)0.8383 (2)0.0325 (6)
C30.7962 (3)0.5995 (2)0.9826 (2)0.0368 (7)
C20.8350 (3)0.5241 (2)0.8967 (2)0.0344 (6)
C50.9503 (3)0.7362 (2)0.9238 (2)0.0414 (7)
H50.98910.80730.93340.050*
C40.8538 (3)0.7050 (2)0.9948 (2)0.0422 (7)
H40.82730.75551.05130.051*
C71.0953 (3)0.6967 (2)0.7614 (2)0.0359 (7)
O11.1524 (2)0.79093 (17)0.78093 (16)0.0458 (5)
O21.12389 (19)0.6316 (2)0.68029 (18)0.0531 (6)
O40.7734 (2)0.42081 (17)0.89033 (19)0.0537 (6)
H4A0.80110.38310.83700.081*
O30.7002 (2)0.56347 (19)1.05036 (17)0.0491 (6)
H30.68530.61291.09830.074*
N10.3697 (2)0.6142 (2)0.6203 (2)0.0417 (6)
C100.4121 (3)0.6946 (3)0.5286 (3)0.0608 (9)
H10A0.49490.67200.50390.073*
H10B0.41780.77200.55950.073*
C120.3732 (4)0.4905 (3)0.5826 (3)0.0574 (9)
H12A0.32050.48170.51620.069*
H12B0.45780.47100.56080.069*
C110.3266 (4)0.6960 (4)0.4277 (3)0.0885 (14)
H11A0.32830.62200.39120.133*
H11B0.35360.75410.37510.133*
H11C0.24310.71280.45230.133*
C130.3304 (5)0.4082 (3)0.6726 (4)0.0840 (13)
H13A0.38830.40940.73480.126*
H13B0.32640.33180.64150.126*
H13C0.24930.43070.69900.126*
C80.4404 (3)0.6357 (3)0.7284 (3)0.0577 (9)
H8A0.40010.59340.78940.069*
H8B0.43490.71710.74660.069*
C90.5759 (3)0.6018 (4)0.7247 (4)0.0822 (13)
H9A0.58250.51970.71610.123*
H9B0.61590.62490.79410.123*
H9C0.61570.63920.66160.123*
H140.288 (2)0.633 (4)0.637 (4)0.123*
O1W0.0402 (3)0.5325 (3)0.4727 (2)0.0719 (8)
H1W−0.035 (2)0.514 (4)0.482 (4)0.108*
H2W0.066 (4)0.568 (3)0.533 (3)0.108*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0341 (15)0.0357 (15)0.0328 (14)0.0014 (13)0.0032 (13)−0.0061 (12)
C60.0319 (15)0.0328 (15)0.0329 (14)0.0021 (12)−0.0029 (12)0.0010 (12)
C30.0340 (16)0.0435 (17)0.0327 (15)0.0026 (14)0.0009 (13)−0.0001 (13)
C20.0343 (16)0.0341 (14)0.0347 (14)−0.0005 (12)−0.0006 (13)−0.0044 (13)
C50.0458 (19)0.0339 (15)0.0446 (16)−0.0034 (14)−0.0005 (15)−0.0077 (14)
C40.0415 (17)0.0403 (18)0.0448 (17)0.0033 (15)0.0063 (15)−0.0131 (14)
C70.0336 (16)0.0405 (17)0.0335 (15)−0.0009 (14)−0.0043 (12)−0.0001 (13)
O10.0550 (13)0.0438 (12)0.0387 (11)−0.0165 (11)0.0005 (10)0.0018 (9)
O20.0471 (14)0.0624 (14)0.0497 (12)−0.0131 (11)0.0134 (11)−0.0191 (11)
O40.0581 (15)0.0441 (13)0.0590 (15)−0.0146 (11)0.0204 (12)−0.0139 (11)
O30.0463 (14)0.0550 (13)0.0459 (12)−0.0037 (11)0.0149 (10)−0.0132 (10)
N10.0393 (15)0.0445 (14)0.0413 (14)−0.0017 (12)0.0058 (12)−0.0020 (11)
C100.055 (2)0.061 (2)0.067 (2)−0.0040 (19)0.0120 (18)0.0178 (18)
C120.065 (2)0.0475 (19)0.060 (2)0.0024 (17)0.0031 (19)−0.0145 (17)
C110.081 (3)0.117 (4)0.068 (3)0.002 (3)−0.003 (2)0.039 (3)
C130.098 (3)0.055 (2)0.099 (3)−0.013 (2)−0.013 (3)0.013 (2)
C80.060 (2)0.060 (2)0.0527 (19)−0.0054 (19)−0.0044 (18)−0.0096 (17)
C90.055 (2)0.099 (3)0.094 (3)−0.003 (2)−0.018 (2)0.003 (3)
O1W0.0682 (19)0.0815 (19)0.0658 (16)−0.0147 (16)0.0034 (15)−0.0133 (14)

Geometric parameters (Å, °)

C1—C21.374 (4)C10—C111.500 (5)
C1—C61.395 (4)C10—H10A0.9700
C1—H10.9300C10—H10B0.9700
C6—C51.387 (4)C12—C131.497 (5)
C6—C71.498 (4)C12—H12A0.9700
C3—O31.368 (3)C12—H12B0.9700
C3—C41.378 (4)C11—H11A0.9600
C3—C21.400 (4)C11—H11B0.9600
C2—O41.370 (3)C11—H11C0.9600
C5—C41.379 (4)C13—H13A0.9600
C5—H50.9300C13—H13B0.9600
C4—H40.9300C13—H13C0.9600
C7—O21.255 (3)C8—C91.505 (5)
C7—O11.273 (3)C8—H8A0.9700
O4—H4A0.8200C8—H8B0.9700
O3—H30.8200C9—H9A0.9600
N1—C101.497 (4)C9—H9B0.9600
N1—C121.501 (4)C9—H9C0.9600
N1—C81.502 (4)O1W—H1W0.841 (19)
N1—H140.92 (2)O1W—H2W0.87 (4)
C2—C1—C6121.3 (3)C11—C10—H10B109.0
C2—C1—H1119.3H10A—C10—H10B107.8
C6—C1—H1119.3C13—C12—N1113.1 (3)
C5—C6—C1118.6 (3)C13—C12—H12A108.9
C5—C6—C7120.6 (2)N1—C12—H12A108.9
C1—C6—C7120.9 (2)C13—C12—H12B108.9
O3—C3—C4123.2 (3)N1—C12—H12B108.9
O3—C3—C2117.0 (3)H12A—C12—H12B107.8
C4—C3—C2119.8 (3)C10—C11—H11A109.5
O4—C2—C1124.5 (2)C10—C11—H11B109.5
O4—C2—C3116.3 (2)H11A—C11—H11B109.5
C1—C2—C3119.3 (3)C10—C11—H11C109.5
C4—C5—C6120.7 (3)H11A—C11—H11C109.5
C4—C5—H5119.7H11B—C11—H11C109.5
C6—C5—H5119.7C12—C13—H13A109.5
C3—C4—C5120.4 (3)C12—C13—H13B109.5
C3—C4—H4119.8H13A—C13—H13B109.5
C5—C4—H4119.8C12—C13—H13C109.5
O2—C7—O1122.5 (3)H13A—C13—H13C109.5
O2—C7—C6119.0 (2)H13B—C13—H13C109.5
O1—C7—C6118.6 (2)N1—C8—C9114.8 (3)
C2—O4—H4A109.5N1—C8—H8A108.6
C3—O3—H3109.5C9—C8—H8A108.6
C10—N1—C12112.0 (2)N1—C8—H8B108.6
C10—N1—C8110.7 (3)C9—C8—H8B108.6
C12—N1—C8113.3 (3)H8A—C8—H8B107.6
C10—N1—H14107 (3)C8—C9—H9A109.5
C12—N1—H14108 (3)C8—C9—H9B109.5
C8—N1—H14105 (3)H9A—C9—H9B109.5
N1—C10—C11113.0 (3)C8—C9—H9C109.5
N1—C10—H10A109.0H9A—C9—H9C109.5
C11—C10—H10A109.0H9B—C9—H9C109.5
N1—C10—H10B109.0H1W—O1W—H2W108 (4)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1W—H2W···O2i0.87 (4)1.98 (2)2.845 (3)173 (4)
O1W—H1W···O3ii0.84 (2)2.14 (2)2.951 (3)162 (4)
N1—H14···O2i0.92 (2)1.83 (2)2.734 (3)166 (5)
O3—H3···O1iii0.821.842.656 (3)173
O4—H4A···O1iv0.821.822.639 (3)174

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ZL2325).

References

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  • Lin, C. Y., Huang, C. S., Huang, C. Y. & Yin, M. C. (2009). J. Agric. Food Chem.57, 6661–6667. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
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  • Yip, E. C. H., Chan, A. S. L., Pang, H., Tam, Y. K. & Wong, Y. H. (2006). Cell Biol. Toxicol.22, 293–302. [PubMed]

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