Dimethyl 2,6-dihydroxy­benzene-1,4-dicarboxyl­ate

The title compound, C₁₀H₁₀O₆, was obtained from an esterification reaction of 2,6-dihydroxy­terephthalic acid and methanol. In the mol­ecular structure, all of the C atoms are nearly coplanar. The two hydr­oxy groups have C2 symmetry. Intra­molecular O—H...O hydrogen bonds are observed. In the crystal, weak O—H...O inter­actions link the mol­ecules.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.049
• wR factor = 0.178
• Data-to-parameter ratio = 14.0

checkCIF/PLATON results

No syntax errors found



Alert level C
CELLV02_ALERT_1_C  The supplied cell volume s.u. differs from that
            calculated from the cell parameter s.u.'s by > 2
            Calculated cell volume su =      13.31
            Cell volume su given      =      11.00
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.27
PLAT432_ALERT_2_C Short Inter X...Y Contact  O5     ..  C1      ..       2.97 Ang.
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT152_ALERT_1_C The Supplied and Calc. Volume s.u. Differ by ...          2 Units

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The title compound as one of terephthalate derivatives, is an important pharmacological and material intermediate (Brunner, 1928; Teruhiko et al., 1998). There is almost no report about crystal structure. As part of our ongoing studies, we now describe the synthesis and the crystal structure of the title compound. In this paper, the crystal structure of it was determined (Fig. 1). The molecule contains benzene ring, dihydroxygroup and dimethyl group. All of atoms except the hydrogen atoms are nearly coplanar. The terminal dimethyl group are centrosymmetric. The dihydroxy group are axisymmetric. In the crystal structure, intramolecular O—H···O hydrogen bonds are observed.

Related literature

For general background to terephthalate derivatives, see: Brunner (1928); Teruhiko et al. (1998). For a related structure, see: Dai et al. (2005).

S2. Experimental

2,6-dihydroxyterephthalic acid (15 mmol) was dissolved in methanol (45 ml), thionyl dichloride (3 ml) was slowly added to the methanol solution afterward, and the mixture was stired at reflux temperature for 72 hours (monitored by TLC). Then the solvent was distilled under vacuum, and the residue was poured into water (50 ml). The pH of the solution was adjusted with sodium bicarbonate to pH = 7.0. The resulting white solid was filtered off, washed with water. The obtained solid was dissolved in methanol. Single crystals were obtained by slow evaporation of a methanol solution.

S3. Refinement

H atoms were placed in calculated position with C—H=0.96 (1) Å(sp3), C—H=0.93 Å(aromatic). All H atoms included in the final cycles of refinement as riding mode, with U_iso(H)=1.2U_eq of the carrier atoms.

Computing details

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Figures

	Fig. 1. The asymmetric unit of the structure of the title compound, with the atomic labeling scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. The molecule packing of the title compound showing O—H···O interactions.

Dimethyl 2,6-dihydroxybenzene-1,4-dicarboxylate

Crystal data

C10H10O6	F(000) = 472
Mr = 226.18	Dx = 1.470 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1855 reflections
a = 11.6462 (8) Å	θ = 2.9–29.2°
b = 7.0925 (3) Å	µ = 0.12 mm^−1
c = 13.5745 (10) Å	T = 293 K
β = 114.327 (9)°	Block, white
V = 1021.70 (11) Å^3	0.34 × 0.26 × 0.20 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur Eos Gemini ultra diffractometer	2083 independent reflections
Radiation source: fine-focus sealed tube	1161 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.023
Detector resolution: 16.0395 pixels mm^-1	θmax = 26.4°, θmin = 3.3°
ω scans	h = −14→10
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	k = −8→8
Tmin = 0.865, Tmax = 1.000	l = −16→15
4572 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.178	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0906P)^2 + 0.0929P] where P = (Fo^2 + 2Fc^2)/3
2083 reflections	(Δ/σ)max = 0.002
149 parameters	Δρmax = 0.26 e Å^−3
0 restraints	Δρmin = −0.21 e Å^−3

Special details

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

	x	y	z	Uiso*/Ueq
O1	1.10292 (17)	0.3212 (3)	0.65789 (15)	0.0531 (6)
O2	1.16658 (17)	0.0296 (3)	0.71430 (17)	0.0594 (6)
O3	1.00830 (17)	−0.2437 (3)	0.65185 (18)	0.0588 (6)
H3	1.0760	−0.1914	0.6860	0.088*
O4	0.8686 (2)	0.3940 (3)	0.5366 (2)	0.0694 (7)
H4	0.9419	0.4218	0.5747	0.104*
O5	0.48877 (19)	−0.0097 (4)	0.36441 (19)	0.0809 (8)
O6	0.55844 (19)	−0.2972 (3)	0.42310 (17)	0.0622 (6)
C1	1.2310 (3)	0.3910 (5)	0.7143 (3)	0.0605 (9)
H1A	1.2712	0.3957	0.6652	0.091*
H1C	1.2773	0.3082	0.7733	0.091*
H1B	1.2290	0.5152	0.7417	0.091*
C2	1.0826 (2)	0.1371 (4)	0.6627 (2)	0.0418 (6)
C3	0.9508 (2)	0.0794 (3)	0.6008 (2)	0.0370 (6)
C4	0.9197 (2)	−0.1122 (3)	0.5979 (2)	0.0393 (6)
C5	0.7983 (2)	−0.1768 (4)	0.5401 (2)	0.0395 (6)
H5	0.7798	−0.3044	0.5397	0.047*
C6	0.7048 (2)	−0.0498 (4)	0.4829 (2)	0.0391 (6)
C7	0.7314 (2)	0.1397 (4)	0.4830 (2)	0.0449 (7)
H7	0.6675	0.2237	0.4438	0.054*
C8	0.8531 (2)	0.2059 (3)	0.5412 (2)	0.0430 (7)
C9	0.5725 (3)	−0.1122 (4)	0.4170 (2)	0.0476 (7)
C10	0.4355 (3)	−0.3758 (5)	0.3582 (3)	0.0769 (11)
H10A	0.4105	−0.3402	0.2840	0.115*
H10B	0.3752	−0.3286	0.3835	0.115*
H10C	0.4392	−0.5108	0.3641	0.115*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0335 (11)	0.0493 (12)	0.0635 (13)	−0.0079 (9)	0.0067 (10)	−0.0032 (10)
O2	0.0326 (10)	0.0563 (12)	0.0718 (14)	0.0062 (9)	0.0039 (10)	0.0043 (11)
O3	0.0360 (11)	0.0445 (11)	0.0775 (14)	0.0103 (9)	0.0048 (10)	0.0115 (11)
O4	0.0480 (13)	0.0347 (11)	0.0953 (18)	0.0029 (9)	−0.0010 (12)	0.0016 (11)
O5	0.0340 (11)	0.0803 (17)	0.0952 (19)	0.0052 (12)	−0.0068 (12)	0.0146 (14)
O6	0.0367 (11)	0.0582 (14)	0.0749 (15)	−0.0086 (10)	0.0062 (10)	−0.0071 (11)
C1	0.0382 (16)	0.070 (2)	0.0634 (19)	−0.0148 (15)	0.0108 (15)	−0.0065 (17)
C2	0.0343 (14)	0.0434 (16)	0.0428 (15)	0.0023 (12)	0.0111 (12)	−0.0003 (13)
C3	0.0298 (13)	0.0377 (14)	0.0389 (14)	0.0039 (11)	0.0094 (11)	−0.0029 (11)
C4	0.0333 (14)	0.0376 (15)	0.0430 (15)	0.0079 (11)	0.0116 (12)	0.0029 (12)
C5	0.0341 (15)	0.0331 (13)	0.0464 (15)	0.0031 (11)	0.0116 (13)	−0.0024 (12)
C6	0.0312 (14)	0.0421 (15)	0.0390 (14)	0.0021 (11)	0.0096 (12)	−0.0025 (11)
C7	0.0298 (14)	0.0459 (17)	0.0460 (16)	0.0130 (12)	0.0026 (12)	0.0021 (13)
C8	0.0366 (15)	0.0346 (15)	0.0498 (16)	0.0029 (11)	0.0097 (13)	−0.0027 (12)
C9	0.0322 (15)	0.0552 (19)	0.0487 (17)	0.0008 (14)	0.0098 (13)	−0.0040 (14)
C10	0.0425 (19)	0.090 (3)	0.084 (2)	−0.0231 (18)	0.0110 (18)	−0.024 (2)

Geometric parameters (Å, º)

O1—C2	1.334 (3)	C2—C3	1.472 (4)
O1—C1	1.454 (3)	C3—C4	1.403 (3)
O2—C2	1.210 (3)	C3—C8	1.413 (3)
O3—C4	1.360 (3)	C4—C5	1.382 (3)
O3—H3	0.8200	C5—C6	1.379 (3)
O4—C8	1.351 (3)	C5—H5	0.9300
O4—H4	0.8200	C6—C7	1.379 (4)
O5—C9	1.190 (3)	C6—C9	1.495 (4)
O6—C9	1.329 (3)	C7—C8	1.389 (4)
O6—C10	1.449 (3)	C7—H7	0.9300
C1—H1A	0.9600	C10—H10A	0.9600
C1—H1C	0.9600	C10—H10B	0.9600
C1—H1B	0.9600	C10—H10C	0.9600
C2—O1—C1	118.1 (2)	C6—C5—H5	120.4
C4—O3—H3	109.5	C4—C5—H5	120.4
C8—O4—H4	109.5	C7—C6—C5	120.8 (2)
C9—O6—C10	117.3 (3)	C7—C6—C9	117.7 (2)
O1—C1—H1A	109.5	C5—C6—C9	121.6 (2)
O1—C1—H1C	109.5	C6—C7—C8	120.4 (2)
H1A—C1—H1C	109.5	C6—C7—H7	119.8
O1—C1—H1B	109.5	C8—C7—H7	119.8
H1A—C1—H1B	109.5	O4—C8—C7	115.6 (2)
H1C—C1—H1B	109.5	O4—C8—C3	124.2 (2)
O2—C2—O1	121.8 (2)	C7—C8—C3	120.3 (2)
O2—C2—C3	124.1 (2)	O5—C9—O6	123.3 (3)
O1—C2—C3	114.1 (2)	O5—C9—C6	124.5 (3)
C4—C3—C8	117.4 (2)	O6—C9—C6	112.2 (2)
C4—C3—C2	118.8 (2)	O6—C10—H10A	109.5
C8—C3—C2	123.8 (2)	O6—C10—H10B	109.5
O3—C4—C5	116.8 (2)	H10A—C10—H10B	109.5
O3—C4—C3	121.3 (2)	O6—C10—H10C	109.5
C5—C4—C3	121.9 (2)	H10A—C10—H10C	109.5
C6—C5—C4	119.3 (2)	H10B—C10—H10C	109.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2	0.82	1.84	2.567 (3)	147
O4—H4···O1	0.82	1.89	2.593 (3)	144
O4—H4···O3^i	0.82	2.58	3.099 (3)	123

Symmetry code: (i) x, y+1, z.