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Journal logoCRYSTALLOGRAPHIC
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ISSN: 2056-9890
Volume 68| Part 5| May 2012| Page o1420

3-Eth­­oxy­carbonyl-2-hy­dr­oxy-6-meth­­oxy-4-methyl­benzoic acid

aSchool of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China, and bSchool of Life and Engineering, Lanzhou University of Technology, Lanzhou 730050, People's Republic of China
*Correspondence e-mail: slpan@shmu.edu.cn

(Received 23 March 2012; accepted 5 April 2012; online 18 April 2012)

The title compound, C12H14O6, a substituted isophthalic acid monoester which was isolated from the lichen Thamnolia vermicularis var. subuliformis, displays intra­molecular carbox­yl–meth­oxy O—H⋯O and hy­droxy–carboxyl O—H⋯O hydrogen-bonding inter­actions. The terminal methyl group of the ethyl ester is disordered over two sets of sites with occupancies of 0.599 (19) and 0.401 (19).

Related literature

For general background to the phenol compounds isolated from the lichen Thamnolia vermicularis var. subuliformis, see: Jiang et al. (2002[Jiang, B., Zhao, Q., Peng, L., Lin, Z. & Sun, H. (2002). Yunnan Zhiwu Yanjiu, 24, 525-530.]); Milenkovic-Andjelkovic (2010[Milenkovic-Andjelkovic, A. (2010). Planta Med. 76, 1304-1304.]). For applications of analogs of the title compound, see: Huneck (1999[Huneck, S. (1999). Naturwissenschaften, 86, 559-570.]).

[Scheme 1]

Experimental

Crystal data
  • C12H14O6

  • Mr = 254.23

  • Triclinic, [P \overline 1]

  • a = 6.8460 (14) Å

  • b = 8.0065 (16) Å

  • c = 11.469 (2) Å

  • α = 97.059 (4)°

  • β = 95.987 (4)°

  • γ = 98.072 (4)°

  • V = 612.9 (2) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.11 mm−1

  • T = 293 K

  • 0.39 × 0.30 × 0.11 mm

Data collection
  • Bruker SMART CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2003[Bruker (2003). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.245, Tmax = 1.000

  • 3352 measured reflections

  • 2359 independent reflections

  • 1379 reflections with I > 2σ(I)

  • Rint = 0.083

Refinement
  • R[F2 > 2σ(F2)] = 0.057

  • wR(F2) = 0.174

  • S = 0.91

  • 2359 reflections

  • 186 parameters

  • 22 restraints

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

  • Δρmax = 0.32 e Å−3

  • Δρmin = −0.21 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O4—H4⋯O2 0.88 (2) 1.77 (3) 2.535 (3) 144 (4)
O1—H1⋯O3 0.84 (2) 1.78 (3) 2.524 (3) 146 (4)

Data collection: SMART (Bruker, 2003[Bruker (2003). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2003[Bruker (2003). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

The title compound, C12H14O6, a substituted isophthalic acid monoester, is one of the phenol compounds isolated from the lichen Thamnolia vermicularis var.subuliformis (Jiang et al., 2002; Milenkovic-Andjelkovic, 2010). The X-ray structural analysis of this compound reported here confirms the assignment of its structure determined from experimental spectroscopic data. In the molecule (Fig. 1), intramolecular carboxylic acid O—H···Omethoxy and hydroxy O—H···Ocarboxyl hydrogen -bonding interactions (Table 1) result in the formation of two six-membered rings. In the crystal (Fig. 2), no significant hydrogen-bonding interactions are found. The terminal methyl group of the ethyl ester is disordered over two sites with occupancies 0.599:0.401.

Related literature top

For general background to the phenol compounds isolated from the lichen Thamnolia vermicularis var.subuliformis, see: Jiang et al. (2002); Milenkovic-Andjelkovic (2010). For applications of analogs of the title compound, see: Huneck (1999).

Experimental top

Extraction of the title compound. The air-dried and powdered plant materials (5 kg) were extracted by 95% EtOH (3 times, 20L) at room temperature and concentrated under vacuum. The residue was partitioned with petroleum ether (PE) and EtOAc,successively. The EtOAc extract (47 g) was chromatographed on a silica gel column eluted successively with PE-EtOAc/ EtOAc–MeOH to afford six major fractions. Fraction 3 eluted with PE-EtOAc (1:3) was further purified by silica gel chromatography [CHCl3-MeOH (15:1)] and then Sephadex LH-20 using MeOH (100%) to yield the title compound (200 mg). The solvent was removed in vacuo to give colorless crystals (m.p. 435–437 K). 1H-NMR (CDCl3, 400 MHz): 12.6 (1H, s, OH), 11.2 (1H, s, COOH), 6.34 (1H, s), 4.4 (2H, q, CH2), 4.08 (3H, s, CH3), 2.37 (3H, s, CH3), 1.39 (3H, t, CH3). Crystals suitable for X-ray diffraction were obtained by slow evaporation of a methanol solution.

Refinement top

Hydroxy and carboxylic acid H-atoms were located in a difference-Fourier analysis and both positional and isotropic displacement parameters were refined. Other H-atoms were positioned geometrically with C—H = 0.93 Å (for aromatic H) or 0.96 or 0.97 Å (for methyl or methylene H-atoms respectively) and constrained to ride on their parent atoms, with Uiso(H) = 1.2 or 1.5 Ueq(C). Disorder in the terminal methyl group (C12) of the ethyl ester resulted in the refinement at two sites with occupancies of 0.599 (19) (C12) and 0.401 (19) (C12').

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids. The disorder in the ethyl ester group is not shown. Intramolecular hydrogen bonds are shown as dashed lines.
[Figure 2] Fig. 2. The crystal packing of the title compound viewed down the a axis.
3-Ethoxycarbonyl-2-hydroxy-6-methoxy-4-methylbenzoic acid top
Crystal data top
C12H14O6Z = 2
Mr = 254.23F(000) = 268
Triclinic, P1Dx = 1.378 Mg m3
Hall symbol: -P 1Melting point = 435–437 K
a = 6.8460 (14) ÅMo Kα radiation, λ = 0.71073 Å
b = 8.0065 (16) ÅCell parameters from 969 reflections
c = 11.469 (2) Åθ = 5.2–52.9°
α = 97.059 (4)°µ = 0.11 mm1
β = 95.987 (4)°T = 293 K
γ = 98.072 (4)°Prismatic, colorless
V = 612.9 (2) Å30.39 × 0.30 × 0.11 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
2359 independent reflections
Radiation source: fine-focus sealed tube1379 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.083
ϕ and ω scansθmax = 26.0°, θmin = 1.8°
Absorption correction: multi-scan
(SADABS; Bruker, 2003)
h = 88
Tmin = 0.245, Tmax = 1.000k = 97
3352 measured reflectionsl = 1413
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)] = 0.057H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.174 w = 1/[σ2(Fo2) + (0.0955P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.91(Δ/σ)max < 0.001
2359 reflectionsΔρmax = 0.32 e Å3
186 parametersΔρmin = 0.21 e Å3
22 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.036 (12)
Crystal data top
C12H14O6γ = 98.072 (4)°
Mr = 254.23V = 612.9 (2) Å3
Triclinic, P1Z = 2
a = 6.8460 (14) ÅMo Kα radiation
b = 8.0065 (16) ŵ = 0.11 mm1
c = 11.469 (2) ÅT = 293 K
α = 97.059 (4)°0.39 × 0.30 × 0.11 mm
β = 95.987 (4)°
Data collection top
Bruker SMART CCD area-detector
diffractometer
2359 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2003)
1379 reflections with I > 2σ(I)
Tmin = 0.245, Tmax = 1.000Rint = 0.083
3352 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.05722 restraints
wR(F2) = 0.174H atoms treated by a mixture of independent and constrained refinement
S = 0.91Δρmax = 0.32 e Å3
2359 reflectionsΔρmin = 0.21 e Å3
186 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*/UeqOcc. (<1)
O10.1285 (4)0.1888 (3)0.3537 (2)0.0692 (7)
O20.3292 (3)0.6477 (3)0.66405 (18)0.0640 (7)
O30.1945 (4)0.1389 (3)0.5664 (2)0.0771 (8)
O40.2762 (4)0.3453 (3)0.7124 (2)0.0773 (8)
O50.0464 (4)0.3799 (4)0.1320 (2)0.0992 (10)
O60.2714 (5)0.3547 (4)0.1310 (2)0.0992 (10)
C10.1806 (4)0.3544 (3)0.3938 (3)0.0501 (8)
C20.2325 (4)0.4167 (3)0.5141 (2)0.0472 (7)
C30.2804 (4)0.5934 (4)0.5465 (2)0.0485 (7)
C40.2788 (4)0.7035 (3)0.4632 (3)0.0518 (8)
H4A0.31100.82040.48670.062*
C50.2289 (4)0.6395 (4)0.3439 (3)0.0526 (8)
C60.1793 (4)0.4666 (4)0.3092 (2)0.0519 (8)
C70.2327 (4)0.2914 (4)0.5983 (3)0.0575 (8)
C80.3758 (6)0.8247 (4)0.7062 (3)0.0777 (11)
H8A0.49670.87080.67830.117*
H8B0.39280.84150.79120.117*
H8C0.26960.88140.67770.117*
C90.2292 (6)0.7624 (4)0.2541 (3)0.0742 (10)
H9A0.35830.83020.26120.111*
H9B0.13170.83550.26820.111*
H9C0.19770.69990.17590.111*
C100.1172 (6)0.3942 (4)0.1827 (3)0.0668 (9)
C110.2310 (10)0.2902 (7)0.0054 (4)0.136 (2)
H11A0.10020.22150.01160.164*0.599 (19)
H11B0.23270.38470.04020.164*0.599 (19)
H11C0.33790.33820.03390.164*0.401 (19)
H11D0.10990.32520.02590.164*0.401 (19)
C120.376 (2)0.1907 (18)0.0273 (7)0.128 (5)0.599 (19)
H12A0.37680.09930.01960.192*0.599 (19)
H12B0.50470.26050.01410.192*0.599 (19)
H12C0.34610.14450.10960.192*0.599 (19)
C12'0.213 (4)0.107 (2)0.0170 (14)0.137 (7)0.401 (19)
H12D0.21470.07200.09990.205*0.401 (19)
H12E0.08990.05710.00650.205*0.401 (19)
H12F0.32190.07090.02760.205*0.401 (19)
H10.144 (7)0.131 (5)0.410 (3)0.113 (16)*
H40.301 (6)0.457 (3)0.728 (4)0.110 (16)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0993 (18)0.0384 (13)0.0710 (16)0.0188 (11)0.0075 (13)0.0049 (10)
O20.0797 (15)0.0543 (14)0.0555 (14)0.0149 (10)0.0031 (10)0.0023 (9)
O30.1013 (19)0.0482 (15)0.0865 (18)0.0195 (12)0.0037 (13)0.0254 (12)
O40.106 (2)0.0709 (18)0.0605 (16)0.0252 (15)0.0042 (13)0.0245 (13)
O50.091 (2)0.126 (3)0.0735 (18)0.0161 (17)0.0105 (15)0.0056 (15)
O60.124 (2)0.132 (3)0.0519 (15)0.069 (2)0.0086 (14)0.0027 (13)
C10.0554 (17)0.0362 (16)0.0614 (19)0.0177 (13)0.0087 (13)0.0047 (12)
C20.0432 (16)0.0471 (17)0.0572 (18)0.0180 (12)0.0096 (13)0.0148 (13)
C30.0434 (16)0.0484 (17)0.0553 (18)0.0148 (12)0.0039 (12)0.0065 (13)
C40.0540 (18)0.0389 (16)0.0638 (19)0.0112 (12)0.0069 (14)0.0073 (13)
C50.0536 (18)0.0469 (17)0.063 (2)0.0151 (13)0.0113 (14)0.0168 (14)
C60.0583 (18)0.0502 (18)0.0519 (18)0.0197 (14)0.0114 (14)0.0091 (13)
C70.0561 (18)0.055 (2)0.069 (2)0.0188 (14)0.0095 (15)0.0221 (15)
C80.096 (3)0.056 (2)0.072 (2)0.0133 (18)0.0136 (19)0.0104 (16)
C90.093 (3)0.061 (2)0.072 (2)0.0127 (18)0.0080 (18)0.0270 (17)
C100.086 (3)0.058 (2)0.060 (2)0.0230 (18)0.0068 (19)0.0108 (15)
C110.199 (5)0.168 (5)0.055 (3)0.097 (5)0.006 (3)0.006 (3)
C120.173 (10)0.159 (9)0.068 (5)0.083 (8)0.021 (5)0.005 (5)
C12'0.163 (13)0.131 (11)0.107 (9)0.037 (9)0.003 (8)0.020 (7)
Geometric parameters (Å, º) top
O1—C11.334 (3)C6—C101.488 (4)
O1—H10.84 (2)C8—H8A0.9600
O2—C31.357 (3)C8—H8B0.9600
O2—C81.420 (4)C8—H8C0.9600
O3—C71.214 (4)C9—H9A0.9600
O4—C71.316 (4)C9—H9B0.9600
O4—H40.88 (2)C9—H9C0.9600
O5—C101.190 (4)C11—C121.411 (10)
O6—C101.321 (4)C11—C12'1.441 (15)
O6—C111.453 (4)C11—H11A0.9700
C1—C21.399 (4)C11—H11B0.9700
C1—C61.401 (4)C11—H11C0.9580
C2—C31.401 (4)C11—H11D0.9607
C2—C71.475 (4)C12—H12A0.9600
C3—C41.377 (4)C12—H12B0.9600
C4—C51.390 (4)C12—H12C0.9600
C4—H4A0.9300C12'—H12D0.9600
C5—C61.376 (4)C12'—H12E0.9600
C5—C91.509 (4)C12'—H12F0.9600
C1—O1—H1110 (3)C5—C9—H9A109.5
C3—O2—C8120.1 (2)C5—C9—H9B109.5
C7—O4—H4113 (3)H9A—C9—H9B109.5
C10—O6—C11115.9 (3)C5—C9—H9C109.5
O1—C1—C2122.7 (2)H9A—C9—H9C109.5
O1—C1—C6116.8 (3)H9B—C9—H9C109.5
C2—C1—C6120.5 (3)O5—C10—O6123.6 (3)
C1—C2—C3117.9 (2)O5—C10—C6125.6 (3)
C1—C2—C7117.7 (3)O6—C10—C6110.8 (3)
C3—C2—C7124.5 (3)C12—C11—O6109.7 (5)
O2—C3—C4122.7 (3)C12'—C11—O6112.2 (7)
O2—C3—C2115.7 (2)C12—C11—H11A109.7
C4—C3—C2121.6 (3)O6—C11—H11A109.7
C3—C4—C5119.8 (3)C12—C11—H11B109.7
C3—C4—H4A120.1O6—C11—H11B109.7
C5—C4—H4A120.1H11A—C11—H11B108.2
C6—C5—C4120.1 (2)C12'—C11—H11C108.5
C6—C5—C9121.0 (3)O6—C11—H11C108.9
C4—C5—C9118.9 (3)C12'—C11—H11D109.6
C5—C6—C1120.2 (3)O6—C11—H11D108.5
C5—C6—C10121.5 (3)H11C—C11—H11D109.1
C1—C6—C10118.3 (3)C11—C12—H12A109.5
O3—C7—O4118.1 (3)C11—C12—H12B109.5
O3—C7—C2122.5 (3)C11—C12—H12C109.5
O4—C7—C2119.4 (3)C11—C12'—H12D109.5
O2—C8—H8A109.5C11—C12'—H12E109.5
O2—C8—H8B109.5H12D—C12'—H12E109.5
H8A—C8—H8B109.5C11—C12'—H12F109.5
O2—C8—H8C109.5H12D—C12'—H12F109.5
H8A—C8—H8C109.5H12E—C12'—H12F109.5
H8B—C8—H8C109.5
O1—C1—C2—C3178.6 (2)C9—C5—C6—C102.2 (5)
C6—C1—C2—C30.6 (4)O1—C1—C6—C5179.2 (3)
O1—C1—C2—C71.4 (4)C2—C1—C6—C50.1 (4)
C6—C1—C2—C7179.4 (2)O1—C1—C6—C101.1 (4)
C8—O2—C3—C41.8 (4)C2—C1—C6—C10178.2 (3)
C8—O2—C3—C2178.6 (3)C1—C2—C7—O31.7 (4)
C1—C2—C3—O2179.8 (2)C3—C2—C7—O3178.3 (3)
C7—C2—C3—O20.2 (4)C1—C2—C7—O4178.4 (3)
C1—C2—C3—C40.5 (4)C3—C2—C7—O41.5 (4)
C7—C2—C3—C4179.5 (2)C11—O6—C10—O50.3 (6)
O2—C3—C4—C5179.5 (2)C11—O6—C10—C6177.2 (3)
C2—C3—C4—C50.1 (4)C5—C6—C10—O583.8 (4)
C3—C4—C5—C60.6 (4)C1—C6—C10—O594.2 (4)
C3—C4—C5—C9179.7 (3)C5—C6—C10—O693.0 (4)
C4—C5—C6—C10.5 (4)C1—C6—C10—O688.9 (4)
C9—C5—C6—C1179.8 (3)C10—O6—C11—C12156.0 (9)
C4—C5—C6—C10177.5 (3)C10—O6—C11—C12'100.3 (13)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O4—H4···O20.88 (2)1.77 (3)2.535 (3)144 (4)
O1—H1···O30.84 (2)1.78 (3)2.524 (3)146 (4)

Experimental details

Crystal data
Chemical formulaC12H14O6
Mr254.23
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)6.8460 (14), 8.0065 (16), 11.469 (2)
α, β, γ (°)97.059 (4), 95.987 (4), 98.072 (4)
V3)612.9 (2)
Z2
Radiation typeMo Kα
µ (mm1)0.11
Crystal size (mm)0.39 × 0.30 × 0.11
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2003)
Tmin, Tmax0.245, 1.000
No. of measured, independent and
observed [I > 2σ(I)] reflections
3352, 2359, 1379
Rint0.083
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.057, 0.174, 0.91
No. of reflections2359
No. of parameters186
No. of restraints22
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.32, 0.21

Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O4—H4···O20.88 (2)1.77 (3)2.535 (3)144 (4)
O1—H1···O30.84 (2)1.78 (3)2.524 (3)146 (4)
 

References

First citationBruker (2003). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationHuneck, S. (1999). Naturwissenschaften, 86, 559–570.  Web of Science CrossRef PubMed CAS Google Scholar
First citationJiang, B., Zhao, Q., Peng, L., Lin, Z. & Sun, H. (2002). Yunnan Zhiwu Yanjiu, 24, 525–530.  CAS Google Scholar
First citationMilenkovic-Andjelkovic, A. (2010). Planta Med. 76, 1304–1304.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
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ISSN: 2056-9890
Volume 68| Part 5| May 2012| Page o1420
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