Ethyl 3-hy­droxy­benzoate

Gutzwiller, A.J.; Addison, G.E.; Hermann, C.K.F.; Harakas, G.N.

doi:10.1107/S2414314626005699

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 11| Part 6| June 2026| x260569

https://doi.org/10.1107/S2414314626005699

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Ethyl 3-hydroxybenzoate

Alexander J. Gutzwiller,^a Grace E. Addison,^a Christine K.F. Hermann ^a and George N. Harakas ^a ^*

^aPO Box 6949, Radford University, Radford, Virginia 24142, USA
^*Correspondence e-mail: [email protected]

Edited by E. R. T. Tiekink, Universitat de les Illes Balears (Received 15 May 2026; accepted 28 May 2026; online 5 June 2026)

The crystal of ethyl 3-hydroxybenzoate, C₉H₁₀O₃, comprises two independent molecules in the asymmetric unit. Each molecule is approximately planar with the ethyl group directed away from the carbonyl-O atom. The planarity is reflected in the phenyl-C—C—O—C(methylene) torsion angles of −179.40 (10) and 177.88 (11)°, respectively. The greatest difference between the molecules is found in the relative orientations of the methyl groups as seen in the carboxylate-C—O—C—C(methyl) torsion angles of −178.76 (11) and −171.12 (13)°, respectively. In the crystal, hydroxyl-O—H⋯O(carbonyl) hydrogen-bonding occurs within almost planar chains along [100].

Keywords: crystal structure; hydrogen bonding.

CCDC reference: 2557954

Structure description

The reaction of 3-hydroxybenzoic acid with ethanol yielded the title compound, ethyl 3-hydroxybenzoate, which has applications in organic synthesis and as a food preservative (Goretti et al., 2009 ). The crystal structure report herein complements an undergraduate Organic Chemistry laboratory experiment (Hermann et al., 2026 ), as detailed in Gutzwiller et al. (2026 ). The title compound crystallizes with two molecules in the asymmetric unit, Fig. 1. Each independent molecule is essentially planar as seen in the value of the C1_1—C7_1—O1_1—C8_1 torsion angle of −179.40 (10)°. The equivalent value for the second independent molecule is 177.88 (11)°. A small deviation in the orientation of the terminal methyl groups is noted: the C7_1—O1_1—C8_1—C9_1 torsion angle is −178.76 (11)° cf. C7_2—O1_2—C8_2—C9_2 of −171.12 (13)°.

Figure 1
The molecular structures of the two independent molecules comprising the title compound showing atom labeling scheme and displacement ellipsoids at the 30% probability level.

Hydrogen-bonding of the type hydroxyl-O—H⋯O(carbonyl) is observed within approximately planar chains along the a-axis direction. The chains stack along the b-axis direction in an ⋯ABA⋯ fashion. The hydrogen-bonding parameters are given in Table 1 and a view of the unit-cell contents is shown in Fig. 2.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2_1—H1_1⋯O3_2ⁱ	0.87 (2)	1.88 (2)	2.7495 (15)	177 (2)
O2_2—H1_2⋯O3_1	0.84 (2)	1.93 (2)	2.7617 (14)	178.1 (14)
Symmetry code: (i) .

Figure 2
Molecular packing diagram viewed in projection down the b axis. Hydrogen-bonding interactions are shown as orange dashed lines.

Synthesis and crystallization

Referring to Fig. 3, the title compound was synthesized through a Fischer esterification. A mixture of of 3-hydroxybenzoic acid (1.5 g), ethanol (10 ml) and concentrated sulfuric acid (1 ml) was refluxed in a 50 ml boiling flask for 1 h. The reaction mixture was allowed to cool, then a solution of 10% sodium carbonate was added until a pH of 8 was obtained. The solution was chilled in an ice-bath until a solid product was formed. The solid was isolated by vacuum filtration.

Figure 3
Reaction scheme for the title compound.

The yield of the crude product was 0.992 g (54.3%) with a melting point of 67.2°C. X-ray quality crystals were produced by dissolving the product into methanol, followed by adding an equal volume of hexanes. The solvent was allowed to evaporate over several days. A single-crystal was coated with NVH oil and mounted on a MiTeGen loop then cooled to 248 K for data collection.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. Owing to poor agreement, one reflection, i.e. 002, was omitted from the final cycles of refinement.

Table 2
Experimental details

Crystal data
Chemical formula	C₉H₁₀O₃
M_r	166.17
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	248
a, b, c (Å)	11.8207 (8), 7.4541 (6), 19.9477 (15)
β (°)	106.776 (2)
V (Å³)	1682.8 (2)
Z	8
Radiation type	Mo Kα
μ (mm⁻¹)	0.10
Crystal size (mm)	0.6 × 0.4 × 0.4

Data collection
Diffractometer	Bruker D8
Absorption correction	Multi-scan (SADAB; Krause et al., 2015 )
T_min, T_max	0.943, 0.962
No. of measured, independent and observed [I > 2σ(I)] reflections	42216, 4174, 3152
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.667

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.129, 1.01
No. of reflections	4174
No. of parameters	225
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.21
Computer programs: APEX3 and SAINT (Bruker, 2019 ), SHELXT2018/2 (Sheldrick, 2015a ), SHELXL2019/3 (Sheldrick, 2015b ) and shelXle (Hübschle et al., 2011 ).

Structural data

CCDC reference: 2557954

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314626005699/tk4125sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314626005699/tk4125Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314626005699/tk4125Isup3.cml

checkCIF report

Computing details top

Ethyl 3-hydroxybenzoate top

Crystal data top

C₉H₁₀O₃	F(000) = 704
M_r = 166.17	D_x = 1.312 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 11.8207 (8) Å	Cell parameters from 9996 reflections
b = 7.4541 (6) Å	θ = 2.9–28.2°
c = 19.9477 (15) Å	µ = 0.10 mm⁻¹
β = 106.776 (2)°	T = 248 K
V = 1682.8 (2) Å³	Block, colourless
Z = 8	0.6 × 0.4 × 0.4 mm

Data collection top

Bruker D8 diffractometer	4174 independent reflections
Radiation source: sealed tube	3152 reflections with I > 2σ(I)
Flat graphite monochromator	R_int = 0.035
Detector resolution: 7.391 pixels mm^-1	θ_max = 28.3°, θ_min = 2.3°
ω and φ scans	h = −15→15
Absorption correction: multi-scan (SADAB; Krause et al., 2015)	k = −9→9
T_min = 0.943, T_max = 0.962	l = −26→26
42216 measured reflections

Refinement top

Refinement on F²	Primary atom site location: Intrinsic Phasing
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.042	Hydrogen site location: mixed
wR(F²) = 0.129	H atoms treated by a mixture of independent and constrained refinement
S = 1.01	w = 1/[σ²(F_o²) + (0.075P)² + 0.2243P] where P = (F_o² + 2F_c²)/3
4174 reflections	(Δ/σ)_max < 0.001
225 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.21 e Å⁻³

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1_1	0.91779 (7)	0.26186 (12)	0.52442 (4)	0.0429 (2)
O2_1	0.99117 (9)	0.39106 (17)	0.29620 (5)	0.0585 (3)
H1_1	1.0520 (18)	0.344 (3)	0.3269 (11)	0.088*
O3_1	0.74342 (8)	0.38538 (14)	0.51992 (5)	0.0521 (3)
C1_1	0.81601 (10)	0.40712 (16)	0.42054 (6)	0.0364 (3)
C2_1	0.71478 (11)	0.49152 (18)	0.37984 (7)	0.0436 (3)
H2_1	0.651122	0.514149	0.398019	0.052*
C3_1	0.70881 (12)	0.5419 (2)	0.31215 (7)	0.0502 (3)
H3_1	0.641020	0.600555	0.284399	0.060*
C4_1	0.80135 (12)	0.5069 (2)	0.28510 (7)	0.0506 (3)
H4_1	0.796059	0.541026	0.238929	0.061*
C5_1	0.90218 (11)	0.42163 (18)	0.32550 (6)	0.0422 (3)
C6_1	0.91060 (10)	0.37347 (16)	0.39395 (6)	0.0374 (3)
H6_1	0.979587	0.318581	0.422117	0.045*
C7_1	0.82072 (10)	0.35279 (16)	0.49288 (6)	0.0378 (3)
C8_1	0.93052 (11)	0.20084 (19)	0.59518 (6)	0.0438 (3)
H8A_1	0.866292	0.118519	0.595989	0.053*
H8B_1	0.928780	0.302882	0.625844	0.053*
C9_1	1.04619 (13)	0.1077 (2)	0.61868 (8)	0.0579 (4)
H9A_1	1.058095	0.061953	0.665739	0.087*
H9B_1	1.108907	0.191394	0.618440	0.087*
H9C_1	1.047199	0.008842	0.587237	0.087*
O1_2	0.35295 (7)	0.31978 (14)	0.37940 (4)	0.0462 (2)
O2_2	0.64798 (8)	0.20855 (16)	0.61254 (5)	0.0547 (3)
H1_2	0.6765 (17)	0.260 (3)	0.5839 (10)	0.082*
O3_2	0.17933 (8)	0.23070 (15)	0.39172 (5)	0.0535 (3)
C1_2	0.35271 (10)	0.19414 (16)	0.48736 (6)	0.0368 (3)
C2_2	0.47221 (10)	0.23244 (16)	0.51480 (6)	0.0374 (3)
H2_2	0.512709	0.295759	0.488075	0.045*
C3_2	0.53107 (10)	0.17608 (17)	0.58216 (6)	0.0394 (3)
C4_2	0.47110 (12)	0.08158 (19)	0.62121 (7)	0.0466 (3)
H4_2	0.511232	0.043009	0.666734	0.056*
C5_2	0.35258 (13)	0.0443 (2)	0.59319 (7)	0.0510 (3)
H5_2	0.312368	−0.020393	0.619708	0.061*
C6_2	0.29236 (12)	0.10108 (19)	0.52656 (7)	0.0453 (3)
H6_2	0.211274	0.076893	0.507945	0.054*
C7_2	0.28568 (11)	0.24977 (17)	0.41548 (6)	0.0392 (3)
C8_2	0.29433 (12)	0.3718 (2)	0.30758 (7)	0.0522 (3)
H8A_2	0.242762	0.475260	0.306633	0.063*
H8B_2	0.246061	0.272506	0.282369	0.063*
C9_2	0.38821 (14)	0.4186 (3)	0.27424 (8)	0.0666 (5)
H9A_2	0.351992	0.451530	0.225729	0.100*
H9B_2	0.439587	0.315993	0.276354	0.100*
H9C_2	0.434153	0.518786	0.298951	0.100*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1_1	0.0392 (5)	0.0542 (5)	0.0374 (5)	0.0024 (4)	0.0143 (4)	0.0068 (4)
O2_1	0.0482 (6)	0.0939 (8)	0.0373 (5)	0.0085 (5)	0.0187 (4)	0.0022 (5)
O3_1	0.0495 (5)	0.0623 (6)	0.0526 (6)	0.0097 (4)	0.0277 (5)	0.0096 (4)
C1_1	0.0369 (6)	0.0366 (6)	0.0361 (6)	−0.0044 (5)	0.0113 (5)	−0.0022 (5)
C2_1	0.0371 (6)	0.0491 (7)	0.0453 (7)	0.0013 (5)	0.0130 (5)	−0.0008 (6)
C3_1	0.0407 (7)	0.0624 (9)	0.0427 (7)	0.0048 (6)	0.0045 (5)	0.0028 (6)
C4_1	0.0487 (7)	0.0680 (9)	0.0328 (6)	0.0002 (7)	0.0079 (5)	0.0011 (6)
C5_1	0.0380 (6)	0.0546 (7)	0.0349 (6)	−0.0036 (5)	0.0117 (5)	−0.0058 (5)
C6_1	0.0352 (6)	0.0406 (6)	0.0359 (6)	−0.0016 (5)	0.0096 (5)	−0.0022 (5)
C7_1	0.0369 (6)	0.0370 (6)	0.0411 (6)	−0.0030 (5)	0.0139 (5)	−0.0008 (5)
C8_1	0.0457 (7)	0.0507 (7)	0.0361 (6)	−0.0046 (6)	0.0136 (5)	0.0046 (5)
C9_1	0.0536 (8)	0.0662 (9)	0.0516 (8)	0.0054 (7)	0.0116 (7)	0.0112 (7)
O1_2	0.0380 (5)	0.0658 (6)	0.0349 (5)	−0.0016 (4)	0.0105 (4)	0.0069 (4)
O2_2	0.0388 (5)	0.0853 (8)	0.0390 (5)	0.0031 (5)	0.0094 (4)	0.0112 (5)
O3_2	0.0365 (5)	0.0722 (7)	0.0497 (6)	−0.0054 (4)	0.0092 (4)	0.0034 (5)
C1_2	0.0387 (6)	0.0398 (6)	0.0349 (6)	0.0009 (5)	0.0154 (5)	−0.0035 (5)
C2_2	0.0381 (6)	0.0432 (6)	0.0347 (6)	0.0031 (5)	0.0163 (5)	0.0015 (5)
C3_2	0.0379 (6)	0.0470 (7)	0.0352 (6)	0.0062 (5)	0.0135 (5)	−0.0007 (5)
C4_2	0.0562 (8)	0.0525 (8)	0.0343 (6)	0.0053 (6)	0.0183 (6)	0.0047 (6)
C5_2	0.0595 (8)	0.0568 (8)	0.0440 (7)	−0.0099 (7)	0.0266 (6)	0.0019 (6)
C6_2	0.0441 (7)	0.0526 (8)	0.0430 (7)	−0.0088 (6)	0.0185 (5)	−0.0048 (6)
C7_2	0.0367 (6)	0.0443 (6)	0.0386 (6)	−0.0003 (5)	0.0139 (5)	−0.0034 (5)
C8_2	0.0469 (7)	0.0711 (9)	0.0354 (7)	−0.0011 (7)	0.0069 (6)	0.0061 (6)
C9_2	0.0590 (9)	0.0982 (13)	0.0464 (8)	0.0049 (9)	0.0212 (7)	0.0156 (8)

Geometric parameters (Å, º) top

O1_1—C7_1	1.3248 (15)	O1_2—C7_2	1.3239 (14)
O1_1—C8_1	1.4489 (14)	O1_2—C8_2	1.4525 (15)
O2_1—C5_1	1.3620 (15)	O2_2—C3_2	1.3609 (15)
O3_1—C7_1	1.2121 (14)	O3_2—C7_2	1.2171 (15)
C1_1—C2_1	1.3878 (17)	C1_2—C6_2	1.3870 (17)
C1_1—C6_1	1.3918 (16)	C1_2—C2_2	1.3892 (17)
C1_1—C7_1	1.4842 (17)	C1_2—C7_2	1.4831 (18)
C2_1—C3_1	1.3835 (19)	C2_2—C3_2	1.3879 (17)
C3_1—C4_1	1.3773 (19)	C3_2—C4_2	1.3872 (18)
C4_1—C5_1	1.3855 (19)	C4_2—C5_2	1.378 (2)
C5_1—C6_1	1.3873 (17)	C5_2—C6_2	1.3807 (19)
C8_1—C9_1	1.484 (2)	C8_2—C9_2	1.4905 (19)

C7_1—O1_1—C8_1	117.09 (9)	C7_2—O1_2—C8_2	116.81 (10)
C2_1—C1_1—C6_1	120.70 (11)	C6_2—C1_2—C2_2	120.70 (12)
C2_1—C1_1—C7_1	118.46 (11)	C6_2—C1_2—C7_2	117.82 (11)
C6_1—C1_1—C7_1	120.83 (11)	C2_2—C1_2—C7_2	121.48 (11)
C3_1—C2_1—C1_1	119.11 (11)	C3_2—C2_2—C1_2	119.21 (11)
C4_1—C3_1—C2_1	120.56 (13)	O2_2—C3_2—C4_2	117.27 (11)
C3_1—C4_1—C5_1	120.41 (12)	O2_2—C3_2—C2_2	122.56 (11)
O2_1—C5_1—C4_1	117.93 (11)	C4_2—C3_2—C2_2	120.18 (12)
O2_1—C5_1—C6_1	122.29 (12)	C5_2—C4_2—C3_2	119.93 (12)
C4_1—C5_1—C6_1	119.77 (12)	C4_2—C5_2—C6_2	120.66 (12)
C5_1—C6_1—C1_1	119.42 (11)	C5_2—C6_2—C1_2	119.33 (12)
O3_1—C7_1—O1_1	123.51 (11)	O3_2—C7_2—O1_2	123.32 (12)
O3_1—C7_1—C1_1	123.80 (11)	O3_2—C7_2—C1_2	123.18 (11)
O1_1—C7_1—C1_1	112.68 (10)	O1_2—C7_2—C1_2	113.49 (10)
O1_1—C8_1—C9_1	106.37 (11)	O1_2—C8_2—C9_2	107.34 (11)

C6_1—C1_1—C2_1—C3_1	0.08 (19)	C6_2—C1_2—C2_2—C3_2	0.13 (18)
C7_1—C1_1—C2_1—C3_1	−179.59 (12)	C7_2—C1_2—C2_2—C3_2	−179.47 (11)
C1_1—C2_1—C3_1—C4_1	0.8 (2)	C1_2—C2_2—C3_2—O2_2	179.98 (11)
C2_1—C3_1—C4_1—C5_1	−0.4 (2)	C1_2—C2_2—C3_2—C4_2	0.45 (18)
C3_1—C4_1—C5_1—O2_1	−179.71 (13)	O2_2—C3_2—C4_2—C5_2	−179.87 (12)
C3_1—C4_1—C5_1—C6_1	−0.9 (2)	C2_2—C3_2—C4_2—C5_2	−0.3 (2)
O2_1—C5_1—C6_1—C1_1	−179.45 (12)	C3_2—C4_2—C5_2—C6_2	−0.4 (2)
C4_1—C5_1—C6_1—C1_1	1.76 (19)	C4_2—C5_2—C6_2—C1_2	1.0 (2)
C2_1—C1_1—C6_1—C5_1	−1.37 (18)	C2_2—C1_2—C6_2—C5_2	−0.83 (19)
C7_1—C1_1—C6_1—C5_1	178.29 (11)	C7_2—C1_2—C6_2—C5_2	178.79 (12)
C8_1—O1_1—C7_1—O3_1	−0.51 (18)	C8_2—O1_2—C7_2—O3_2	−1.23 (19)
C8_1—O1_1—C7_1—C1_1	−179.40 (10)	C8_2—O1_2—C7_2—C1_2	177.88 (11)
C2_1—C1_1—C7_1—O3_1	−3.67 (19)	C6_2—C1_2—C7_2—O3_2	6.19 (19)
C6_1—C1_1—C7_1—O3_1	176.66 (12)	C2_2—C1_2—C7_2—O3_2	−174.20 (12)
C2_1—C1_1—C7_1—O1_1	175.22 (11)	C6_2—C1_2—C7_2—O1_2	−172.92 (11)
C6_1—C1_1—C7_1—O1_1	−4.45 (16)	C2_2—C1_2—C7_2—O1_2	6.69 (17)
C7_1—O1_1—C8_1—C9_1	−178.76 (11)	C7_2—O1_2—C8_2—C9_2	−171.12 (13)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2_1—H1_1···O3_2ⁱ	0.87 (2)	1.88 (2)	2.7495 (15)	177 (2)
O2_2—H1_2···O3_1	0.84 (2)	1.93 (2)	2.7617 (14)	178.1 (14)

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

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