The crystal structure of the title compound, C8H8O4, is characterized by extensive hydrogen-bonding interactions to yield centrosymmetrically related dimers linked to each other by intermolecular interactions between the hydroxy groups and between the hydroxy and methyl groups.
Supporting information
CCDC reference: 214606
Key indicators
- Single-crystal X-ray study
- T = 295 K
- Mean (C-C) = 0.002 Å
- R factor = 0.044
- wR factor = 0.140
- Data-to-parameter ratio = 16.2
checkCIF results
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ADDSYM reports no extra symmetry
2,5-Dihydroxybenzoic acid (24.6 g, 159.5 mmol) was dissolved in methanol (500 ml). Sulfuric acid (98%, 10 ml) was added dropwise and the mixture stirred under reflux for 72 h. Removal of the solvent under reduced pressure yielded a yellow oil that was partitioned between chloroform (200 ml) and deionized water (100 ml). The organic layer was dried (magnesium sulfate) and condensed to yield the title compound as a crystalline white solid. Yield 24.5 g, 80.0%; m.p. 357–359 K (literature: 357–359 K; Malcolm, 1981). Crystals suitable for X-ray diffraction studies were prepared by slow evaporation at room temperature of a solution of 30 mg of (I) in a solution of diethyl ether (2 ml) and hexane (5 ml).
H atoms were located at calculated positions with C—H set to 0.95 Å. Hydroxy H atoms were located from difference Fourier maps and the O—H bond length set to 0.85 Å. Uiso values for the H atoms were set at 1.2Ueq of the parent atom.
Data collection: MSC/AFC7 Diffractometer Control Software for Windows
(Molecular Structure Corporation, 1999); cell refinement: MSC/AFC7 Diffractometer Control Software for Windows; data reduction: TEXSAN for Windows (Molecular Structure Corporation, 1997-2001); program(s) used to solve structure: TEXSAN for Windows; program(s) used to refine structure: TEXSAN for Windows and SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: TEXSAN for Windows and PLATON (Spek, 1980-2001).
Methyl 2,5-dihydroxybenzoate
top
Crystal data top
C8H8O4 | F(000) = 352 |
Mr = 168.14 | Dx = 1.440 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: -P 2yn | Cell parameters from 25 reflections |
a = 12.316 (2) Å | θ = 12.6–17.2° |
b = 12.986 (2) Å | µ = 0.12 mm−1 |
c = 4.8795 (6) Å | T = 295 K |
β = 96.406 (12)° | Prismatic, colorless |
V = 775.5 (2) Å3 | 0.40 × 0.30 × 0.30 mm |
Z = 4 | |
Data collection top
Rigaku AFC-7R diffractometer | Rint = 0.029 |
Radiation source: Rigaku rotating anode | θmax = 27.5°, θmin = 3.1° |
Graphite monochromator | h = −7→15 |
ω–2θ scans | k = 0→16 |
2012 measured reflections | l = −6→6 |
1784 independent reflections | 3 standard reflections every 150 reflections |
1353 reflections with I > 2σ(I) | intensity decay: 0.5% |
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)] = 0.044 | H-atom parameters not refined |
wR(F2) = 0.140 | w = 1/[σ2(Fo2) + (0.092P)2 + 0.1P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max < 0.001 |
1784 reflections | Δρmax = 0.23 e Å−3 |
110 parameters | Δρmin = −0.19 e Å−3 |
0 restraints | Extinction correction: SHELXL97, FC*=KFC[1+0.001XFC2Λ3/SIN(2Θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.033 (9) |
Crystal data top
C8H8O4 | V = 775.5 (2) Å3 |
Mr = 168.14 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 12.316 (2) Å | µ = 0.12 mm−1 |
b = 12.986 (2) Å | T = 295 K |
c = 4.8795 (6) Å | 0.40 × 0.30 × 0.30 mm |
β = 96.406 (12)° | |
Data collection top
Rigaku AFC-7R diffractometer | Rint = 0.029 |
2012 measured reflections | 3 standard reflections every 150 reflections |
1784 independent reflections | intensity decay: 0.5% |
1353 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.044 | 0 restraints |
wR(F2) = 0.140 | H-atom parameters not refined |
S = 1.03 | Δρmax = 0.23 e Å−3 |
1784 reflections | Δρmin = −0.19 e Å−3 |
110 parameters | |
Special details top
Experimental. The scan width was (1.84 + 0.30tanθ)° with an ω scan speed of 16° per minute (up to 4 scans to achieve I/σ(I) > 10). Stationary background counts were recorded at each end of the scan, and the scan time:background time ratio was 2:1. |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All e.s.d.'s are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
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 | Uiso*/Ueq | |
O21 | −0.05155 (9) | 0.61114 (10) | 0.3442 (3) | 0.0536 (4) | |
O51 | 0.23480 (9) | 0.86979 (10) | 0.9592 (3) | 0.0512 (4) | |
O71 | 0.11486 (9) | 0.53975 (9) | 0.1116 (2) | 0.0511 (4) | |
O72 | 0.28205 (8) | 0.60082 (8) | 0.2479 (2) | 0.0448 (3) | |
C1 | 0.13566 (11) | 0.67001 (11) | 0.4560 (3) | 0.0360 (4) | |
C2 | 0.02443 (11) | 0.67113 (12) | 0.4920 (3) | 0.0404 (4) | |
C3 | −0.01199 (12) | 0.73664 (14) | 0.6876 (3) | 0.0483 (5) | |
C4 | 0.05920 (13) | 0.80102 (13) | 0.8406 (3) | 0.0464 (5) | |
C5 | 0.16959 (12) | 0.80239 (11) | 0.8026 (3) | 0.0389 (4) | |
C6 | 0.20744 (11) | 0.73648 (11) | 0.6123 (3) | 0.0371 (4) | |
C7 | 0.17441 (12) | 0.59739 (11) | 0.2548 (3) | 0.0378 (4) | |
C8 | 0.32540 (15) | 0.52997 (14) | 0.0596 (4) | 0.0532 (5) | |
H3 | −0.08710 | 0.73670 | 0.71650 | 0.0580* | |
H4 | 0.03290 | 0.84520 | 0.97400 | 0.0560* | |
H6 | 0.28280 | 0.73620 | 0.58740 | 0.0440* | |
H8A | 0.29750 | 0.54690 | −0.12430 | 0.0640* | |
H8B | 0.30430 | 0.46180 | 0.09990 | 0.0640* | |
H8C | 0.40280 | 0.53470 | 0.07910 | 0.0640* | |
H21 | −0.02210 | 0.58030 | 0.21680 | 0.0640* | |
H51 | 0.29860 | 0.86940 | 0.90670 | 0.0610* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O21 | 0.0335 (6) | 0.0668 (8) | 0.0614 (7) | −0.0041 (5) | 0.0093 (5) | −0.0160 (6) |
O51 | 0.0422 (6) | 0.0575 (7) | 0.0549 (7) | −0.0028 (5) | 0.0105 (5) | −0.0157 (5) |
O71 | 0.0438 (6) | 0.0540 (7) | 0.0562 (7) | −0.0041 (5) | 0.0083 (5) | −0.0130 (5) |
O72 | 0.0373 (6) | 0.0459 (6) | 0.0538 (6) | 0.0008 (4) | 0.0163 (5) | −0.0093 (5) |
C1 | 0.0334 (7) | 0.0378 (7) | 0.0382 (7) | 0.0029 (5) | 0.0096 (5) | 0.0054 (6) |
C2 | 0.0317 (7) | 0.0471 (8) | 0.0430 (7) | 0.0014 (6) | 0.0068 (6) | 0.0023 (6) |
C3 | 0.0329 (7) | 0.0616 (10) | 0.0522 (9) | 0.0042 (7) | 0.0125 (6) | −0.0048 (8) |
C4 | 0.0406 (8) | 0.0534 (9) | 0.0471 (8) | 0.0075 (7) | 0.0137 (6) | −0.0061 (7) |
C5 | 0.0378 (7) | 0.0398 (7) | 0.0398 (7) | 0.0027 (6) | 0.0072 (6) | 0.0013 (6) |
C6 | 0.0315 (7) | 0.0406 (7) | 0.0406 (7) | 0.0024 (5) | 0.0106 (5) | 0.0029 (6) |
C7 | 0.0359 (7) | 0.0379 (7) | 0.0407 (7) | 0.0015 (6) | 0.0098 (6) | 0.0039 (6) |
C8 | 0.0533 (9) | 0.0500 (9) | 0.0604 (10) | 0.0048 (7) | 0.0243 (8) | −0.0092 (8) |
Geometric parameters (Å, º) top
O21—C2 | 1.361 (2) | C2—C3 | 1.390 (2) |
O51—C5 | 1.363 (2) | C3—C4 | 1.371 (2) |
O71—C7 | 1.2133 (18) | C4—C5 | 1.393 (2) |
O72—C7 | 1.3306 (18) | C5—C6 | 1.382 (2) |
O72—C8 | 1.444 (2) | C3—H3 | 0.9512 |
O21—H21 | 0.8536 | C4—H4 | 0.9512 |
O51—H51 | 0.8532 | C6—H6 | 0.9494 |
C1—C7 | 1.478 (2) | C8—H8A | 0.9502 |
C1—C2 | 1.4005 (19) | C8—H8B | 0.9494 |
C1—C6 | 1.399 (2) | C8—H8C | 0.9494 |
| | | |
O21···O71 | 2.6205 (17) | C8···O51x | 3.283 (2) |
O21···O71i | 3.0012 (18) | C2···H51ii | 2.8156 |
O21···O51ii | 2.7622 (17) | C3···H51ii | 2.9160 |
O51···C8iii | 3.283 (2) | C4···H8Cviii | 3.0563 |
O51···C7iii | 3.404 (2) | C5···H8Biv | 2.8960 |
O51···C8iv | 3.296 (2) | C6···H8Aix | 2.9368 |
O51···O21v | 2.7622 (17) | C7···H21 | 2.4168 |
O71···O71i | 3.0934 (16) | H3···O51ii | 2.7723 |
O71···O21i | 3.0012 (18) | H3···O72viii | 2.6698 |
O71···O21 | 2.6205 (17) | H3···H6viii | 2.5717 |
O72···C3vi | 3.338 (2) | H3···H51ii | 2.3854 |
O21···H51ii | 1.9206 | H6···O72 | 2.4149 |
O51···H8Aiv | 2.8237 | H6···H51 | 2.3216 |
O51···H3v | 2.7723 | H6···H3vi | 2.5717 |
O51···H8Biii | 2.5533 | H8A···O71 | 2.6403 |
O71···H21 | 1.8919 | H8A···C6vii | 2.9368 |
O71···H8B | 2.5497 | H8A···O51xi | 2.8237 |
O71···H21i | 2.4279 | H8B···O71 | 2.5497 |
O71···H8A | 2.6403 | H8B···O51x | 2.5533 |
O72···H6 | 2.4149 | H8B···C5xi | 2.8960 |
O72···H3vi | 2.6698 | H8C···C4vi | 3.0563 |
C1···C4vii | 3.488 (2) | H21···O71 | 1.8919 |
C3···O72viii | 3.338 (2) | H21···C7 | 2.4168 |
C4···C1ix | 3.488 (2) | H21···O71i | 2.4279 |
C4···C7ix | 3.529 (2) | H21···H51ii | 2.5726 |
C5···C8iv | 3.448 (2) | H51···H6 | 2.3216 |
C5···C7ix | 3.454 (2) | H51···O21v | 1.9206 |
C7···C5vii | 3.454 (2) | H51···C2v | 2.8156 |
C7···C4vii | 3.529 (2) | H51···C3v | 2.9160 |
C7···O51x | 3.404 (2) | H51···H3v | 2.3854 |
C8···C5xi | 3.448 (2) | H51···H21v | 2.5726 |
C8···O51xi | 3.296 (2) | | |
| | | |
C7—O72—C8 | 115.78 (12) | O72—C7—C1 | 113.07 (12) |
C2—O21—H21 | 109.36 | O71—C7—O72 | 123.09 (13) |
C5—O51—H51 | 109.43 | O71—C7—C1 | 123.84 (14) |
C6—C1—C7 | 121.62 (13) | C2—C3—H3 | 119.74 |
C2—C1—C7 | 118.86 (13) | C4—C3—H3 | 119.49 |
C2—C1—C6 | 119.51 (13) | C3—C4—H4 | 119.64 |
O21—C2—C3 | 117.31 (13) | C5—C4—H4 | 119.70 |
O21—C2—C1 | 123.50 (13) | C1—C6—H6 | 119.68 |
C1—C2—C3 | 119.19 (14) | C5—C6—H6 | 119.76 |
C2—C3—C4 | 120.77 (14) | O72—C8—H8A | 109.45 |
C3—C4—C5 | 120.66 (14) | O72—C8—H8B | 109.46 |
C4—C5—C6 | 119.29 (14) | O72—C8—H8C | 109.48 |
O51—C5—C4 | 117.16 (13) | H8A—C8—H8B | 109.44 |
O51—C5—C6 | 123.55 (13) | H8A—C8—H8C | 109.45 |
C1—C6—C5 | 120.56 (13) | H8B—C8—H8C | 109.55 |
| | | |
C8—O72—C7—O71 | −0.8 (2) | C2—C1—C7—O72 | −177.40 (13) |
C8—O72—C7—C1 | 178.67 (13) | C6—C1—C7—O71 | −178.64 (14) |
C6—C1—C2—O21 | 178.27 (14) | O21—C2—C3—C4 | −178.62 (15) |
C6—C1—C2—C3 | −1.6 (2) | C1—C2—C3—C4 | 1.2 (2) |
C6—C1—C7—O72 | 1.9 (2) | C2—C3—C4—C5 | 0.2 (2) |
C7—C1—C2—O21 | −2.4 (2) | C3—C4—C5—O51 | 178.89 (15) |
C7—C1—C2—C3 | 177.78 (14) | C3—C4—C5—C6 | −1.3 (2) |
C2—C1—C6—C5 | 0.5 (2) | O51—C5—C6—C1 | −179.26 (14) |
C7—C1—C6—C5 | −178.84 (14) | C4—C5—C6—C1 | 0.9 (2) |
C2—C1—C7—O71 | 2.0 (2) | | |
Symmetry codes: (i) −x, −y+1, −z; (ii) x−1/2, −y+3/2, z−1/2; (iii) −x+1/2, y+1/2, −z+3/2; (iv) −x+1/2, y+1/2, −z+1/2; (v) x+1/2, −y+3/2, z+1/2; (vi) x+1/2, −y+3/2, z−1/2; (vii) x, y, z−1; (viii) x−1/2, −y+3/2, z+1/2; (ix) x, y, z+1; (x) −x+1/2, y−1/2, −z+3/2; (xi) −x+1/2, y−1/2, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O21—H21···O71 | 0.85 | 1.89 | 2.6205 (17) | 142 |
O21—H21···O71i | 0.85 | 2.43 | 3.0012 (18) | 125 |
O51—H51···O21v | 0.85 | 1.92 | 2.7622 (17) | 169 |
C8—H8B···O51x | 0.95 | 2.55 | 3.283 (2) | 134 |
Symmetry codes: (i) −x, −y+1, −z; (v) x+1/2, −y+3/2, z+1/2; (x) −x+1/2, y−1/2, −z+3/2. |
Experimental details
Crystal data |
Chemical formula | C8H8O4 |
Mr | 168.14 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 295 |
a, b, c (Å) | 12.316 (2), 12.986 (2), 4.8795 (6) |
β (°) | 96.406 (12) |
V (Å3) | 775.5 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.40 × 0.30 × 0.30 |
|
Data collection |
Diffractometer | Rigaku AFC-7R diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2012, 1784, 1353 |
Rint | 0.029 |
(sin θ/λ)max (Å−1) | 0.650 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.140, 1.03 |
No. of reflections | 1784 |
No. of parameters | 110 |
H-atom treatment | H-atom parameters not refined |
Δρmax, Δρmin (e Å−3) | 0.23, −0.19 |
Selected geometric parameters (Å, º) topO21—C2 | 1.361 (2) | O72—C7 | 1.3306 (18) |
O51—C5 | 1.363 (2) | O72—C8 | 1.444 (2) |
O71—C7 | 1.2133 (18) | | |
| | | |
C7—O72—C8 | 115.78 (12) | O51—C5—C6 | 123.55 (13) |
O21—C2—C3 | 117.31 (13) | O72—C7—C1 | 113.07 (12) |
O21—C2—C1 | 123.50 (13) | O71—C7—O72 | 123.09 (13) |
O51—C5—C4 | 117.16 (13) | O71—C7—C1 | 123.84 (14) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O21—H21···O71 | 0.85 | 1.89 | 2.6205 (17) | 142 |
O21—H21···O71i | 0.85 | 2.43 | 3.0012 (18) | 125 |
O51—H51···O21ii | 0.85 | 1.92 | 2.7622 (17) | 169 |
C8—H8B···O51iii | 0.95 | 2.55 | 3.283 (2) | 134 |
Symmetry codes: (i) −x, −y+1, −z; (ii) x+1/2, −y+3/2, z+1/2; (iii) −x+1/2, y−1/2, −z+3/2. |
The title compound, (I), was prepared as a prototype receptor with multiple functionality for coordination to analytes. The structure of (I) shows the molecules to be planar (Fig. 1) with bond lengths and angles in accord with conventional values (Allen et al., 1987). Pairs of centrosymmetrically related molecules are associated through bifurcated intra- and intermolecular hydrogen-bonding interactions between the α-hydroxy group and carbonyl O atoms to form a carboxylic acid dimer motif. Further hydrogen-bonding is observed between the 2- and 5-hydroxy groups on adjacent molecules (Fig. 2). In addition, the structure is stabilized through weak C—H····O hydrogen-bonding interactions between the ester methyl group and 5-hydroxy groups on adjacent molecules.