Acta Cryst. (2004). E60, o865±o867 DOI: 10.1107/S1600536804009377 Cengiz Arõcõ et al.  C 13 H 12 N 2 O 3 o865 organic papers Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368 4-Acetyl-5-methyl-1-phenyl-1H-pyrazole- 3-carboxylic acid Cengiz Arõcõ, a *DincËerU È lku È, a MustafaSacËmacõ, b SË.Hakan U È ngo Èren b and Yunus AkcËamur b a Department of Engineering Physics, Hacettepe University, Beytepe 06800, Ankara, Turkey, and b Department of Chemistry, Yozgat Faculty of Arts and Sciences, Erciyes University, 66200 Yozgat, Turkey Correspondence e-mail: arici@hacettepe.edu.tr Key indicators Single-crystal X-ray study T = 293 K Mean (C±C) = 0.003 A Ê R factor = 0.040 wR factor = 0.109 Data-to-parameter ratio = 12.7 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. # 2004 International Union of Crystallography Printed in Great Britain ± all rights reserved In the title compound, C 13 H 12 N 2 O 3 , the phenyl ring is nearly planar, with a maximum deviation of 0.012 (1) A Ê . The pyrazole ring is planar and forms a 48.45 (5)  dihedral angle with the phenyl ring. There is an intramolecular OÐHO hydrogen bond between the hydroxy group and the ketone group. The packing is governed by weak CÐHN,O interactions. Comment Some pyrazoles are known to possess considerable anti- microbial, antiviral, antitumor, anti-in¯ammatory, anti- histaminic and phytotoxic activities (Mahajan et al., 1991; Janus et al. , 1999; Katayama & Oshiyama, 1997; Badawey & El-Ashmawey, 1998; Mishra et al., 1998; Bernard et al., 1985). As part of our current interest in such compounds, we synthesized and studied the X-ray structure of the title compound, (I). The phenyl ring is nearly planar, with a maximum deviation of 0.012 (1) A Ê for atom C9. The pyrazole ring is planar and forms a 48.45 (5)  dihedral angle with the phenyl ring. The carboxylic moiety is slightly twisted by 3.9 (1)  with respect to the pyrazole ring, whereas the ketone group makes a 2.9 (1)  angle with the pyrazole ring. The N1ÐC4 bond length of 1.442 (2) A Ê corresponds to a CÐN single bond. Received 5 March 2004 Accepted 19 April 2004 Online 30 April 2004 Figure 1 ORTEPIII (Burnett & Johnson, 1996) view of the title compound, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as small circles of arbitrary radii. The hydrogen bond is shown dashed.