4-(Imidazol-1-yl)benzoic acid

In the title molecule, C10H8N2O2, the imidazole and benzene rings form a dihedral angle of 14.5 (1)°. In the crystal, intermolecular O—H⋯N hydrogen bonds link the molecules into chains extending in [01], which are further linked into sheets parallel to (102) through weak C—H⋯O interactions.

In the title molecule, C 10 H 8 N 2 O 2 , the imidazole and benzene rings form a dihedral angle of 14.5 (1) . In the crystal, intermolecular O-HÁ Á ÁN hydrogen bonds link the molecules into chains extending in [101], which are further linked into sheets parallel to (102) through weak C-HÁ Á ÁO interactions.

Comment
The molecules of the title compound, (I), are often used as coordinating ligands in the metal complexes (Gao et al., 2009;Zhang et al., 2007). Herewith we presenet the crystal structure of (I).
In (I) (Fig.1), the imidazole ring is twisted out of the plane of benzene ring at 14.5 (1)°. In the crystal structure, intermolecular O-H···N hydrogen bonds (Table 1) link the molecules into chains extended in direction [-101]. These chains are further linked into sheets parallel to the plane (102) through the weak C-H···O interactions (Table 1).

Experimental
A 150 ml round-bottom flask was charged with a magnetic stirrer and a reflux condenser, iminazole (44 mmol), K 2 CO 3 (6.00 g, 43 mmol), 30 ml DMSO and a little Aliquat 336 were added. 4-fluorobenzaldehyde (4.5 ml, 42 mmol) was added dropwise to the mixture at 363 K and stirred for 15 min. Then the reaction mixture was refluxed for 24 h at 353 K, cooled to room temperature, poured into 150 ml ice-water and filtered. The primrose yellow crude product was obtained, washed with distilled water, and dried in vacuo at room temperature, then purified by recrystallization with ethyl acetate to give the desired analytical pure intermediate products. Intermediate product (12.5 mmol) and 15 ml 20% (wt) NaOH (aq) were added to a round-bottom flask equipped with a magnetic stirrer and a reflux condenser at 333 K for 30 min. Then AgNO 3 (4.00 g, 24 mmol) was added to the mixture group by group. The reaction mixture was refluxed for 24 h at 333 K, cooled to room temperature and filtered. Excessive HCl (1 M) was added to the filtrate and adjust pH to 2, a great deal of sediments were obtained and then filtered. The crude product was recrystallized with ethanol. 4-imidazolylbenzoic acid: Yellow crystals.

Refinement
All hydrogen atoms were placed in geometrically idealized positions (O-H = 0.82 Å, C-H = 0.93 Å) and constrained to ride on their parent atoms, with U iso (H) = 1.2 U eq (C) or 1.5 U eq (O). Due to the absence of any significant anomalous scatterers in the molecule, the 408 Friedel pairs were merged before the final refinement. Fig. 1. The molecular structure of (I) showing 30% probability displacement ellipsoids.