2-(3-Methoxyphenoxy)benzoic acid

In the crystal structure of the title compound, C14H12O4, the molecules form classical O—H⋯O hydrogen-bonded carboxylic acid dimers. These dimers are linked by C—H⋯pi; interactions into a three-dimensional network. The benzene rings are oriented at a dihedral angle of 69.6 (3)°.

In the crystal structure of the title compound, C 14 H 12 O 4 , the molecules form classical O-HÁ Á ÁO hydrogen-bonded carboxylic acid dimers. These dimers are linked by C-HÁ Á Ápi; interactions into a three-dimensional network. The benzene rings are oriented at a dihedral angle of 69.6 (3) .
The author gratefully acknowledges financial support from the Natural Science Foundation of the Education Department of Shaanxi Provincial Government (09JK844) and is grateful for support provided by the key industry problem plan of Yulin (gygg200807) and the special research projects of Yulin University (08YK17).

Comment
The title compound, 2-(3-methoxyphenoxy)benzoic acid is an important intermediate of xanthone dicarboxylic acids (Jackson et al., 1972). Xanthone dicarboxylic acid, such as LY223982, which inhibited the binding of LTB4 to receptors on intact human neutrophils nearly as well as nonradioactive LTB4 (Gapinski et al., 1990). Knowledge of the crystal structure of such benzoicacid derivatives gives us not only information about nuclearity of the complex molecule, but is important in understanding the behaviour of these compounds with respect to the mechanisms of pharmacological activities and physiological activities. Therefore, we have synthesized the title compound, (I), and report its crystal structure here.
The molecular structure of (I) is shown in Fig. 1, and the intermolecular O-H···O hydrogen bond (Table 1) results in the formation of carboxylic acid dimers ( Fig. 2.). The bond lengths are within normal ranges (Allen et al., 1987). Similar crystal structure of some compounds have been reported (Shi et al., 2011;Raghunathan et al., 1982).
In the molecule of (I), the dihedral angle of the rings(C3-C6) and (C8-C13) is 69.6 (3)°, the molecules were connected together via O-H···O intermolecular hydrogen bonds to form dimers. These dimers are linked by C-H···π and weak C-H···O interactions to give a three-dimensional network, which seems to be very effective in the stabilization of the crystal structure.

Experimental
The title compound (I) was prepared by the method of Ullmann condensation reaction reported in literature (Pellón et al., 1995). A mixture of 2-chlorobenzoic acid (6.26 g, 0.04 mol), 3-methoxyphenol (9.93 g, 0.08 mol), anhydrous K 2 CO 3 (11.04 g' 0.08 mol), pyridine (1.58 g' 0.02 mol), Cu powder (0.2 g) and cuprous iodide (0.2 g) in 25 ml water was kept at reflux for two hours. The mixture was then basified with Na 2 CO 3 solution and extracted with diethyl ether. The aqueous solution was acidified with HCl, the precipitated solid was filtered off and disolved in NaOH; the basic solution was filtered (charcoal) and acidified with acetic acid. The 2-(3-methoxyphenoxy)benzoic acid was crystalized from the mixture.   Fig. 1. The molecular structure of (I) (thermal ellipsoids are shown at 30% probability levels). Fig. 2. The structure of a dimer of (I).