3,4,5-Trimethoxyphenol

The asymmetric unit of the title compound, C9H12O4, consists of two crystallographically independent molecules with similar conformations: essentially planar [r.m.s deviations for C6O4 = 0.0057 and 0.0137 Å] except for the central methoxy-methyl group [C—C—O—C torsion angles = 83.3 (2) and 83.9 (2)°]. In the crystal, O—H⋯O hydrogen bonds link the molecules, generating supramolecular chains along the b axis.The three-dimensional crystal structure is stabilized by C—H⋯O and C—H⋯π interactions.


Comment
The study of the energetics of phenolic compounds (Matos et al., 2008) has considerable practical interest since this class of chemical compound includes a large number of synthetic and naturally occurring antioxidants. They inhibit the oxidation of materials of both commercial and biological importance. This antioxidant function is due to the ability of phenols to trap the peroxyl radicals via the hydrogen transfer reaction (Gong et al., 2009). In order to expand this field, we now report the structure of the title compound.
The molecule of the title compound ( Fig. 1), consists of two crystallographically independent molecules, A and B, with similar conformations. All O-atoms in both molecules are coplanar with the benzene rings they are attached to, and the mean r.s.m in molecules A and B are 0.0057 and 0.0137 Å, respectively.
In the crystal, it is worth mentioning that strong intermolecular O-H···O hydrogen bonds link molecules A and B to generate a one dimensional chain ( Fig. 2 and Table 1) along the b axis. These are connected into a supramolecular layer in the bc plane by C-H···O and C-H···π interactions ( Table 1). The layers are connected into a three-dimensional crystal structure by C-H···O hydrogen bonds (Table 2) involving the C13 and O1 atoms (Table 1).

Experimental
3,4,5-Trimethoxyphenol was obtained commercially from Aldrich Chemical Co. Single crystals suitable for X-ray diffraction were obtained by recrystallizing the prude product from its chloroform solution by slow evaporation at room temperature over a period of seven days.

Refinement
All H atoms were placed in idealized positions (C-H = 0.93-0.96 Å, O-H = 0.82 Å) and refined as riding atoms with U iso (H) = 1.2U eq (C) and U iso (H) = 1.5U eq (O).  The molecular structure of the title compound, with displacement ellipsoids at the 30% probability level.

Figure 2
A potion of the unit cell contents highlighting the chain structure of the title compound, linked via O-H···O hydrogen bonds (dashed lines). H atoms have been omitted for clarity, except for those involved in hydrogen-bonded interactions.

3,4,5-Trimethoxyphenol
Crystal data 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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.