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

Deng, Y.-X.; Guo, T.; Xie, H.; Pan, S.-L.

doi:10.1107/S1600536812015012

organic compounds

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ISSN: 2056-9890

Volume 68| Part 5| May 2012| Page o1420

doi:10.1107/S1600536812015012

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

Yun-Xia Deng,^a Tao Guo,^b Hui Xie ^a and Sheng-Li Pan ^a ^*

^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 ); Milenkovic-Andjelkovic (2010 ). For applications of analogs of the title compound, see: Huneck (1999 ).

Experimental

Crystal data

C₁₂H₁₄O₆
M_r = 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 ) T_min = 0.245, T_max = 1.000
3352 measured reflections
2359 independent reflections
1379 reflections with I > 2σ(I)
R_int = 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
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	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); 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); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812015012/zs2195sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812015012/zs2195Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812015012/zs2195Isup3.cml

checkCIF report

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···O_methoxy and hydroxy O—H···O_carboxyl 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.

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

	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.
	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

C₁₂H₁₄O₆	Z = 2
M_r = 254.23	F(000) = 268
Triclinic, P1	D_x = 1.378 Mg m⁻³
Hall symbol: -P 1	Melting point = 435–437 K
a = 6.8460 (14) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.0065 (16) Å	Cell parameters from 969 reflections
c = 11.469 (2) Å	θ = 5.2–52.9°
α = 97.059 (4)°	µ = 0.11 mm⁻¹
β = 95.987 (4)°	T = 293 K
γ = 98.072 (4)°	Prismatic, colorless
V = 612.9 (2) Å³	0.39 × 0.30 × 0.11 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	2359 independent reflections
Radiation source: fine-focus sealed tube	1379 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.083
ϕ and ω scans	θ_max = 26.0°, θ_min = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2003)	h = −8→8
T_min = 0.245, T_max = 1.000	k = −9→7
3352 measured reflections	l = −14→13

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.057	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.174	w = 1/[σ²(F_o²) + (0.0955P)²] where P = (F_o² + 2F_c²)/3
S = 0.91	(Δ/σ)_max < 0.001
2359 reflections	Δρ_max = 0.32 e Å⁻³
186 parameters	Δρ_min = −0.21 e Å⁻³
22 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.036 (12)

Crystal data top

C₁₂H₁₄O₆	γ = 98.072 (4)°
M_r = 254.23	V = 612.9 (2) Å³
Triclinic, P1	Z = 2
a = 6.8460 (14) Å	Mo Kα radiation
b = 8.0065 (16) Å	µ = 0.11 mm⁻¹
c = 11.469 (2) Å	T = 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)
T_min = 0.245, T_max = 1.000	R_int = 0.083
3352 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.057	22 restraints
wR(F²) = 0.174	H atoms treated by a mixture of independent and constrained refinement
S = 0.91	Δρ_max = 0.32 e Å⁻³
2359 reflections	Δρ_min = −0.21 e Å⁻³
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

	x	y	z	U_iso*/U_eq	Occ. (<1)
O1	0.1285 (4)	0.1888 (3)	0.3537 (2)	0.0692 (7)
O2	0.3292 (3)	0.6477 (3)	0.66405 (18)	0.0640 (7)
O3	0.1945 (4)	0.1389 (3)	0.5664 (2)	0.0771 (8)
O4	0.2762 (4)	0.3453 (3)	0.7124 (2)	0.0773 (8)
O5	−0.0464 (4)	0.3799 (4)	0.1320 (2)	0.0992 (10)
O6	0.2714 (5)	0.3547 (4)	0.1310 (2)	0.0992 (10)
C1	0.1806 (4)	0.3544 (3)	0.3938 (3)	0.0501 (8)
C2	0.2325 (4)	0.4167 (3)	0.5141 (2)	0.0472 (7)
C3	0.2804 (4)	0.5934 (4)	0.5465 (2)	0.0485 (7)
C4	0.2788 (4)	0.7035 (3)	0.4632 (3)	0.0518 (8)
H4A	0.3110	0.8204	0.4867	0.062*
C5	0.2289 (4)	0.6395 (4)	0.3439 (3)	0.0526 (8)
C6	0.1793 (4)	0.4666 (4)	0.3092 (2)	0.0519 (8)
C7	0.2327 (4)	0.2914 (4)	0.5983 (3)	0.0575 (8)
C8	0.3758 (6)	0.8247 (4)	0.7062 (3)	0.0777 (11)
H8A	0.4967	0.8708	0.6783	0.117*
H8B	0.3928	0.8415	0.7912	0.117*
H8C	0.2696	0.8814	0.6777	0.117*
C9	0.2292 (6)	0.7624 (4)	0.2541 (3)	0.0742 (10)
H9A	0.3583	0.8302	0.2612	0.111*
H9B	0.1317	0.8355	0.2682	0.111*
H9C	0.1977	0.6999	0.1759	0.111*
C10	0.1172 (6)	0.3942 (4)	0.1827 (3)	0.0668 (9)
C11	0.2310 (10)	0.2902 (7)	0.0054 (4)	0.136 (2)
H11A	0.1002	0.2215	−0.0116	0.164*	0.599 (19)
H11B	0.2327	0.3847	−0.0402	0.164*	0.599 (19)
H11C	0.3379	0.3382	−0.0339	0.164*	0.401 (19)
H11D	0.1099	0.3252	−0.0259	0.164*	0.401 (19)
C12	0.376 (2)	0.1907 (18)	−0.0273 (7)	0.128 (5)	0.599 (19)
H12A	0.3768	0.0993	0.0196	0.192*	0.599 (19)
H12B	0.5047	0.2605	−0.0141	0.192*	0.599 (19)
H12C	0.3461	0.1445	−0.1096	0.192*	0.599 (19)
C12'	0.213 (4)	0.107 (2)	−0.0170 (14)	0.137 (7)	0.401 (19)
H12D	0.2147	0.0720	−0.0999	0.205*	0.401 (19)
H12E	0.0899	0.0571	0.0065	0.205*	0.401 (19)
H12F	0.3219	0.0709	0.0276	0.205*	0.401 (19)
H1	0.144 (7)	0.131 (5)	0.410 (3)	0.113 (16)*
H4	0.301 (6)	0.457 (3)	0.728 (4)	0.110 (16)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0993 (18)	0.0384 (13)	0.0710 (16)	0.0188 (11)	0.0075 (13)	0.0049 (10)
O2	0.0797 (15)	0.0543 (14)	0.0555 (14)	0.0149 (10)	−0.0031 (10)	0.0023 (9)
O3	0.1013 (19)	0.0482 (15)	0.0865 (18)	0.0195 (12)	0.0037 (13)	0.0254 (12)
O4	0.106 (2)	0.0709 (18)	0.0605 (16)	0.0252 (15)	0.0042 (13)	0.0245 (13)
O5	0.091 (2)	0.126 (3)	0.0735 (18)	0.0161 (17)	−0.0105 (15)	0.0056 (15)
O6	0.124 (2)	0.132 (3)	0.0519 (15)	0.069 (2)	0.0086 (14)	−0.0027 (13)
C1	0.0554 (17)	0.0362 (16)	0.0614 (19)	0.0177 (13)	0.0087 (13)	0.0047 (12)
C2	0.0432 (16)	0.0471 (17)	0.0572 (18)	0.0180 (12)	0.0096 (13)	0.0148 (13)
C3	0.0434 (16)	0.0484 (17)	0.0553 (18)	0.0148 (12)	0.0039 (12)	0.0065 (13)
C4	0.0540 (18)	0.0389 (16)	0.0638 (19)	0.0112 (12)	0.0069 (14)	0.0073 (13)
C5	0.0536 (18)	0.0469 (17)	0.063 (2)	0.0151 (13)	0.0113 (14)	0.0168 (14)
C6	0.0583 (18)	0.0502 (18)	0.0519 (18)	0.0197 (14)	0.0114 (14)	0.0091 (13)
C7	0.0561 (18)	0.055 (2)	0.069 (2)	0.0188 (14)	0.0095 (15)	0.0221 (15)
C8	0.096 (3)	0.056 (2)	0.072 (2)	0.0133 (18)	−0.0136 (19)	−0.0104 (16)
C9	0.093 (3)	0.061 (2)	0.072 (2)	0.0127 (18)	0.0080 (18)	0.0270 (17)
C10	0.086 (3)	0.058 (2)	0.060 (2)	0.0230 (18)	0.0068 (19)	0.0108 (15)
C11	0.199 (5)	0.168 (5)	0.055 (3)	0.097 (5)	0.006 (3)	−0.006 (3)
C12	0.173 (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—C1	1.334 (3)	C6—C10	1.488 (4)
O1—H1	0.84 (2)	C8—H8A	0.9600
O2—C3	1.357 (3)	C8—H8B	0.9600
O2—C8	1.420 (4)	C8—H8C	0.9600
O3—C7	1.214 (4)	C9—H9A	0.9600
O4—C7	1.316 (4)	C9—H9B	0.9600
O4—H4	0.88 (2)	C9—H9C	0.9600
O5—C10	1.190 (4)	C11—C12	1.411 (10)
O6—C10	1.321 (4)	C11—C12'	1.441 (15)
O6—C11	1.453 (4)	C11—H11A	0.9700
C1—C2	1.399 (4)	C11—H11B	0.9700
C1—C6	1.401 (4)	C11—H11C	0.9580
C2—C3	1.401 (4)	C11—H11D	0.9607
C2—C7	1.475 (4)	C12—H12A	0.9600
C3—C4	1.377 (4)	C12—H12B	0.9600
C4—C5	1.390 (4)	C12—H12C	0.9600
C4—H4A	0.9300	C12'—H12D	0.9600
C5—C6	1.376 (4)	C12'—H12E	0.9600
C5—C9	1.509 (4)	C12'—H12F	0.9600

C1—O1—H1	110 (3)	C5—C9—H9A	109.5
C3—O2—C8	120.1 (2)	C5—C9—H9B	109.5
C7—O4—H4	113 (3)	H9A—C9—H9B	109.5
C10—O6—C11	115.9 (3)	C5—C9—H9C	109.5
O1—C1—C2	122.7 (2)	H9A—C9—H9C	109.5
O1—C1—C6	116.8 (3)	H9B—C9—H9C	109.5
C2—C1—C6	120.5 (3)	O5—C10—O6	123.6 (3)
C1—C2—C3	117.9 (2)	O5—C10—C6	125.6 (3)
C1—C2—C7	117.7 (3)	O6—C10—C6	110.8 (3)
C3—C2—C7	124.5 (3)	C12—C11—O6	109.7 (5)
O2—C3—C4	122.7 (3)	C12'—C11—O6	112.2 (7)
O2—C3—C2	115.7 (2)	C12—C11—H11A	109.7
C4—C3—C2	121.6 (3)	O6—C11—H11A	109.7
C3—C4—C5	119.8 (3)	C12—C11—H11B	109.7
C3—C4—H4A	120.1	O6—C11—H11B	109.7
C5—C4—H4A	120.1	H11A—C11—H11B	108.2
C6—C5—C4	120.1 (2)	C12'—C11—H11C	108.5
C6—C5—C9	121.0 (3)	O6—C11—H11C	108.9
C4—C5—C9	118.9 (3)	C12'—C11—H11D	109.6
C5—C6—C1	120.2 (3)	O6—C11—H11D	108.5
C5—C6—C10	121.5 (3)	H11C—C11—H11D	109.1
C1—C6—C10	118.3 (3)	C11—C12—H12A	109.5
O3—C7—O4	118.1 (3)	C11—C12—H12B	109.5
O3—C7—C2	122.5 (3)	C11—C12—H12C	109.5
O4—C7—C2	119.4 (3)	C11—C12'—H12D	109.5
O2—C8—H8A	109.5	C11—C12'—H12E	109.5
O2—C8—H8B	109.5	H12D—C12'—H12E	109.5
H8A—C8—H8B	109.5	C11—C12'—H12F	109.5
O2—C8—H8C	109.5	H12D—C12'—H12F	109.5
H8A—C8—H8C	109.5	H12E—C12'—H12F	109.5
H8B—C8—H8C	109.5

O1—C1—C2—C3	−178.6 (2)	C9—C5—C6—C10	−2.2 (5)
C6—C1—C2—C3	0.6 (4)	O1—C1—C6—C5	179.2 (3)
O1—C1—C2—C7	1.4 (4)	C2—C1—C6—C5	−0.1 (4)
C6—C1—C2—C7	−179.4 (2)	O1—C1—C6—C10	1.1 (4)
C8—O2—C3—C4	1.8 (4)	C2—C1—C6—C10	−178.2 (3)
C8—O2—C3—C2	−178.6 (3)	C1—C2—C7—O3	1.7 (4)
C1—C2—C3—O2	179.8 (2)	C3—C2—C7—O3	−178.3 (3)
C7—C2—C3—O2	−0.2 (4)	C1—C2—C7—O4	−178.4 (3)
C1—C2—C3—C4	−0.5 (4)	C3—C2—C7—O4	1.5 (4)
C7—C2—C3—C4	179.5 (2)	C11—O6—C10—O5	−0.3 (6)
O2—C3—C4—C5	179.5 (2)	C11—O6—C10—C6	−177.2 (3)
C2—C3—C4—C5	−0.1 (4)	C5—C6—C10—O5	−83.8 (4)
C3—C4—C5—C6	0.6 (4)	C1—C6—C10—O5	94.2 (4)
C3—C4—C5—C9	−179.7 (3)	C5—C6—C10—O6	93.0 (4)
C4—C5—C6—C1	−0.5 (4)	C1—C6—C10—O6	−88.9 (4)
C9—C5—C6—C1	179.8 (3)	C10—O6—C11—C12	−156.0 (9)
C4—C5—C6—C10	177.5 (3)	C10—O6—C11—C12'	−100.3 (13)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	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)

Experimental details

Crystal data
Chemical formula	C₁₂H₁₄O₆
M_r	254.23
Crystal system, space group	Triclinic, 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)
V (Å³)	612.9 (2)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.11
Crystal size (mm)	0.39 × 0.30 × 0.11

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2003)
T_min, T_max	0.245, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	3352, 2359, 1379
R_int	0.083
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.057, 0.174, 0.91
No. of reflections	2359
No. of parameters	186
No. of restraints	22
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	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···A	D—H	H···A	D···A	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)

References

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Volume 68| Part 5| May 2012| Page o1420

doi:10.1107/S1600536812015012

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