2,4,6-Trihydroxy­anisole

The title compound, C₇H₈O₄, crystallizes with three inter­molecular O—H...O hydrogen bonds, yielding a structure with a tightly knit pattern of hydrogen bonding.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.047
• wR factor = 0.125
• Data-to-parameter ratio = 7.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       7.73
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.54 Ratio
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.48

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.95
           From the CIF: _reflns_number_total                861
           Count of symmetry unique reflns          881
           Completeness (_total/calc)             97.73%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

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

   0 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
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The title compound, (I), 2,4,6-trihydroxyanisole, was first isolated by De Laire & Tiemann (1893) as a degradation product of a glucoside obtained from Iris Jorentina. Although it is a well known intermediate for synthesis of several natural isoflavones such as tectorigenin, irigenin and caviunin (Baker et al., 1970), its crystal structure has not been reported. In this article, the title comound was prepared by the method of Damschroder & Shriner (1937) with appropriate modifications.

The molecular structure is shown in Fig. 1. A l l the hydrogen atoms of the hydroxyl groups contribute to the formation of intermolecular O—H···O hydrogen bonds (Table 1), and every molecule is involved in hydrogen bond interactions with six other molecules, which leads to the formation of a three-dimensional network (Fig. 2). To our surprise, O2 was not involved in any hydrogen bond interactions. This may be due to steric hindrance around the oxygen atom. The methyl group (C7) is 1.084 (5) Å out of the plane of the benzene ring which prevents close stacking of the molecules (Fig. 3). Face to face distances between benzene rings are 4.482 (3) Å).

Related literature

For related literature, see: Baker et al. (1970); Damschroder & Shriner (1937); De Laire & Tiemann (1893).

S2. Experimental

A solution of 3.7 g of 2,4,6-trinitroanisole in 70 ml of absolute ethanol was reduced with hydrogen at a pressure of 3 atm in the presence of platinum oxide (0.1 g). After ten minutes, the reduction mixture was filtered quickly, and the solvent removed with a water pump, at the same time slowly flowing N₂(g) through the solution. The mixture was then cooled in an ice bath, the product removed by filtration and washed with small amounts of cold absolute ethanol. 2,4,6-Triaminoanisole (1.77 g, 76%) was obtained by recrystallization from hot absolute ethanol. A solution of 1.5 g of the crude triaminoanisole in 60 ml of air-free water containing 3 ml of concentrated hydrochloric acid was refluxed for 20 h in an atmosphere of carbon dioxide. After filtration, the water was removed by vacuum distillation, passing a stream of carbon dioxide. The dry residue was then thoroughly extracted with three 60 ml portions of ether. The combined ether extracts were dried over magnesium sulfate, and the ether was removed by distillation. 2,4,6-trihydroxyanisole was obtained in 65% yield. The purified products were dissolved in ethyl acetate, and petroleum ether was added carefully. The crystals suitable for X-ray analysis were obtained after 3 days by volatilization of the solvents.

S3. Refinement

H atoms bonded to C were placed in geometrically idealized positions and constrained to ride on their parent atoms, with U_iso(H) = 1.2U_eq(C) and with C—H = 0.93 Å for the aromatic H atoms, C—H = 0.96 Å for the aliphatic H atoms. H atoms bonded to O were located from adifference electron density map and refined with a restrained O—H distance of 0.92 (2) Å.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The structure of 2,4,6-trihydroxyanisole, showing 30% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. The crystal packing of 2,4,6-trihydroxyanisole, viewed along the a axis. Dashed lines indicate O—H···O hydrogen bonds.
	Fig. 3. The crystal packing of 2,4,6-trihydroxyanisole, viewed along the b axis.

2,4,6-Trihydroxyanisole

Crystal data

C7H8O4	F(000) = 328
Mr = 156.13	Dx = 1.397 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 558 reflections
a = 5.231 (1) Å	θ = 2.8–26.2°
b = 9.4010 (19) Å	µ = 0.12 mm^−1
c = 15.095 (3) Å	T = 298 K
V = 742.3 (3) Å^3	Block, colourless
Z = 4	0.30 × 0.20 × 0.20 mm

Data collection

Bruker SMART APEX diffractometer	736 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.041
Graphite monochromator	θmax = 26.0°, θmin = 2.6°
φ and ω scans	h = 0→6
881 measured reflections	k = 0→11
861 independent reflections	l = 0→18

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.047	w = 1/[σ^2(Fo^2) + (0.077P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.125	(Δ/σ)max < 0.001
S = 1.08	Δρmax = 0.20 e Å^−3
861 reflections	Δρmin = −0.25 e Å^−3
114 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997a), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.056 (11)
Primary atom site location: structure-invariant direct methods	Absolute structure: indeterminate
Secondary atom site location: difference Fourier map

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
O3	1.0972 (6)	0.7137 (2)	0.66584 (13)	0.0401 (7)
O2	1.1104 (4)	0.4545 (2)	0.74132 (13)	0.0318 (6)
O1	0.9108 (6)	0.2206 (2)	0.65022 (13)	0.0378 (7)
O4	0.6225 (6)	0.5306 (2)	0.42132 (14)	0.0474 (8)
C6	0.7719 (7)	0.3719 (3)	0.53482 (19)	0.0328 (8)
H6	0.7001	0.2941	0.5061	0.039*
C4	0.8600 (7)	0.6234 (3)	0.5401 (2)	0.0337 (8)
H4	0.8463	0.7134	0.5150	0.040*
C1	0.8988 (7)	0.3553 (3)	0.61421 (18)	0.0276 (7)
C3	0.9875 (7)	0.6045 (3)	0.6196 (2)	0.0293 (7)
C2	1.0050 (6)	0.4702 (3)	0.65761 (18)	0.0267 (7)
C5	0.7536 (8)	0.5070 (3)	0.4988 (2)	0.0326 (7)
C7	1.3791 (9)	0.4384 (6)	0.7426 (3)	0.0679 (13)
H7A	1.4238	0.3467	0.7193	0.102*
H7B	1.4398	0.4464	0.8024	0.102*
H7C	1.4562	0.5113	0.7069	0.102*
H3	1.094 (10)	0.796 (5)	0.633 (2)	0.071 (14)*
H4A	0.560 (8)	0.449 (4)	0.400 (2)	0.062 (13)*
H1	0.902 (10)	0.224 (5)	0.7092 (12)	0.070 (14)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O3	0.0739 (17)	0.0161 (10)	0.0303 (11)	−0.0086 (13)	−0.0086 (14)	0.0010 (9)
O2	0.0438 (12)	0.0274 (11)	0.0242 (10)	−0.0019 (11)	−0.0028 (11)	0.0025 (9)
O1	0.0757 (17)	0.0119 (9)	0.0256 (10)	0.0040 (12)	−0.0020 (14)	0.0028 (8)
O4	0.085 (2)	0.0186 (10)	0.0383 (13)	−0.0033 (14)	−0.0263 (15)	0.0025 (10)
C6	0.055 (2)	0.0145 (13)	0.0291 (15)	−0.0028 (15)	−0.0009 (17)	−0.0018 (12)
C4	0.055 (2)	0.0133 (12)	0.0329 (15)	0.0004 (16)	−0.0041 (16)	0.0030 (12)
C1	0.0449 (17)	0.0113 (12)	0.0267 (13)	0.0045 (14)	0.0025 (15)	0.0035 (11)
C3	0.0455 (17)	0.0142 (13)	0.0280 (15)	−0.0026 (14)	0.0008 (15)	−0.0023 (11)
C2	0.0399 (16)	0.0186 (14)	0.0215 (13)	0.0010 (14)	0.0034 (14)	−0.0008 (12)
C5	0.0491 (18)	0.0220 (14)	0.0266 (14)	0.0010 (13)	−0.0073 (16)	0.0015 (11)
C7	0.053 (2)	0.089 (3)	0.061 (3)	0.010 (3)	−0.009 (3)	0.003 (3)

Geometric parameters (Å, º)

O3—C3	1.368 (4)	C6—H6	0.9300
O3—H3	0.92 (4)	C4—C5	1.377 (4)
O2—C2	1.386 (3)	C4—C3	1.384 (4)
O2—C7	1.414 (5)	C4—H4	0.9300
O1—C1	1.379 (3)	C1—C2	1.381 (4)
O1—H1	0.892 (18)	C3—C2	1.390 (4)
O4—C5	1.374 (4)	C7—H7A	0.9600
O4—H4A	0.89 (4)	C7—H7B	0.9600
C6—C1	1.379 (4)	C7—H7C	0.9600
C6—C5	1.384 (4)
C3—O3—H3	110 (3)	O3—C3—C2	116.3 (3)
C2—O2—C7	114.8 (3)	C4—C3—C2	120.5 (3)
C1—O1—H1	111 (3)	C1—C2—O2	120.6 (2)
C5—O4—H4A	111 (2)	C1—C2—C3	119.2 (3)
C1—C6—C5	118.6 (3)	O2—C2—C3	120.0 (3)
C1—C6—H6	120.7	O4—C5—C4	117.3 (3)
C5—C6—H6	120.7	O4—C5—C6	121.2 (3)
C5—C4—C3	119.0 (3)	C4—C5—C6	121.5 (3)
C5—C4—H4	120.5	O2—C7—H7A	109.5
C3—C4—H4	120.5	O2—C7—H7B	109.5
C6—C1—O1	117.9 (3)	H7A—C7—H7B	109.5
C6—C1—C2	121.1 (2)	O2—C7—H7C	109.5
O1—C1—C2	120.9 (3)	H7A—C7—H7C	109.5
O3—C3—C4	123.2 (2)	H7B—C7—H7C	109.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H4A···O1^i	0.89 (4)	1.93 (4)	2.823 (3)	177 (4)
O3—H3···O4^ii	0.92 (4)	1.83 (4)	2.743 (3)	172 (4)
O1—H1···O3^iii	0.89 (2)	1.89 (2)	2.778 (3)	174 (5)

Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) x+1/2, −y+3/2, −z+1; (iii) −x+2, y−1/2, −z+3/2.