A triclinic modification of 3,4-dihy­droxy­benzoic acid monohydrate

Seik Weng Ng

doi:10.1107/S1600536811034635

. 2011 Aug 27;67(Pt 9):o2476. doi: 10.1107/S1600536811034635

A triclinic modification of 3,4-dihydroxybenzoic acid monohydrate

Seik Weng Ng ^a,^*

PMCID: PMC3200807 PMID: 22059032

Abstract

The unit cell of the title compound, C₇H₆O₄·H₂O, features four independent formula units; the individual carboxylic acid molecules themselves are nearly planar (r.m.s. deviations = 0.0189, 0.0334, 0.0356 and 0.0441 Å). Two independent molecules each form two hydrogen bonds by acid–carbonyl O—H⋯O interactions and the dimers are also nearly planar (r.m.s. deviations = 0.039 and 0.049 Å). The two independent dimers are aligned at 44.5 (1)°. Other O—H⋯O interactions involving the hydroxy groups and water molecules give rise to a three-dimensional network.

Related literature

For the triclinic modification whose cell is about half the volume of the present triclinic modification, see: Horneffer et al. (1999 ▶).

Experimental

Crystal data

C₇H₆O₄·H₂O
M _r = 172.13
Triclinic,
a = 7.1105 (3) Å
b = 12.7807 (5) Å
c = 17.5318 (7) Å
α = 72.491 (4)°
β = 89.901 (3)°
γ = 74.457 (3)°
V = 1458.45 (10) Å³
Z = 8
Cu Kα radiation
μ = 1.18 mm⁻¹
T = 100 K
0.20 × 0.10 × 0.10 mm

Data collection

Agilent Technologies SuperNova Dual diffractometer with Atlas detector
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ▶) T _min = 0.798, T _max = 0.891
9167 measured reflections
5301 independent reflections
4910 reflections with I > 2σ(I)
R _int = 0.020

Refinement

R[F ² > 2σ(F ²)] = 0.056
wR(F ²) = 0.161
S = 1.15
5301 reflections
513 parameters
24 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.35 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2010 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811034635/xu5306sup1.cif

e-67-o2476-sup1.cif^{(26.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811034635/xu5306Isup2.hkl

e-67-o2476-Isup2.hkl^{(259.5KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811034635/xu5306Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O6	0.85 (1)	1.83 (1)	2.678 (3)	178 (3)
O3—H3⋯O1Wⁱ	0.84 (1)	1.99 (1)	2.803 (3)	163 (3)
O4—H4⋯O4Wⁱⁱ	0.84 (1)	1.86 (2)	2.674 (3)	163 (4)
O5—H5⋯O2	0.85 (1)	1.76 (1)	2.593 (3)	170 (4)
O7—H7⋯O3ⁱⁱⁱ	0.84 (1)	1.91 (1)	2.746 (3)	172 (4)
O8—H8⋯O3W^iv	0.84 (1)	1.94 (1)	2.772 (3)	171 (4)
O9—H9⋯O14	0.84 (1)	1.84 (2)	2.664 (3)	166 (5)
O11—H11⋯O3W^v	0.84 (1)	2.02 (2)	2.824 (3)	161 (4)
O12—H12⋯O1W	0.84 (1)	1.92 (1)	2.760 (3)	175 (4)
O13—H13⋯O10	0.84 (1)	1.76 (1)	2.599 (3)	171 (5)
O15—H15⋯O11^vi	0.84 (1)	1.91 (1)	2.754 (2)	178 (4)
O16—H16⋯O2W^vii	0.84 (1)	1.92 (2)	2.699 (3)	153 (4)
O1W—H1W1⋯O2	0.84 (1)	2.36 (5)	2.920 (3)	124 (4)
O1W—H1W2⋯O2W^viii	0.84 (1)	2.07 (1)	2.911 (4)	173 (7)
O2W—H2W1⋯O6	0.85 (1)	2.24 (1)	3.071 (3)	168 (4)
O2W—H2W2⋯O7^ix	0.85 (1)	2.00 (2)	2.823 (3)	165 (4)
O3W—H3W1⋯O10	0.85 (1)	2.40 (4)	2.933 (3)	122 (3)
O3W—H3W2⋯O4W^x	0.84 (1)	2.08 (1)	2.920 (4)	174 (6)
O4W—H4W1⋯O14	0.85 (1)	2.30 (3)	3.079 (3)	152 (5)
O4W—H4W2⋯O15^xi	0.86 (1)	1.97 (1)	2.806 (3)	164 (4)

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) ; (viii) ; (ix) ; (x) ; (xi) .

Acknowledgments

Dr M. Raza Shah of the University of Karachi is thanked for providing the crystal for the study, and the University of Malaya for supporting this study.

supplementary crystallographic information

Comment

3,4-Dihydroxybenzoic acid monohydrate (Scheme I) was reported as a triclinic crystal [a 8.045, b 8.134, c 12.692 Å; α 71.58, β 76.79, γ 72.17 °]; there are two independent formula units in the unit cell (Horneffer et al., 1999). The carboxylic acid is a commerically available compound. This carboxylic acid when isolated from a plant crystallizes as a monohydrate and its unit cell is twice as large so that there are four independent molecules (Fig. 1). The individual carboxylic acid molecules themselves are planar. Two independent molecules form two hydrogen bonds by O–H_acid···O_carbonyl interactions. Other O–H···O interactions that involve the hydroxy groups and water molecules give rise to a three-dimensional network (Table 1).

Experimental

The aerial part of Dodonaea viscosa (20 kg) was powdered and extracted with methanol (10 L x 3) at room temperature and the crude residue (2 kg) was obtained after removal of methanol under reduced pressure. The residue was suspended in water and extracted with n-hexane,chloroform, ethyl acetate and n-butanol. The ethyl acetate fraction (250 g) was subjected repeatedly to column chromatography on silica gel. The compound (10 mg) was found in a polarity range 50% ethyl acetate to 50% ethyl acetate:n-hexane. Crystals of 3,4-dihydroxybenzoic acid monohydrate were the unexpected compound that were obtained by recrystallization from a 1:1 acetone:n-hexane mixture.