4-Methyl-5-phenyl-1H-pyrazol-3(2H)-one

Abstract

The asymmetric unit of the title compound, C10H10N2O, contains two crystallographically independent mol­ecules with similar geometries, which exist in the keto form. The C=O bond lengths are 1.2878 (12) Å in mol­ecule A and 1.2890 (12) Å in mol­ecule B, indicating that the compound undergoes enol-to-keto tautomerism during the crystallization process. In mol­ecule A, the pyrazole ring is approximately planar [maximum deviation = 0.007 (1) Å] and forms a dihedral angle of 36.67 (6)° with the attached phenyl ring. In mol­ecule B, the dihedral angle formed between the pyrazole ring [maximum deviation = 0.017 (1) Å] and the phenyl ring is 41.19 (6)°. In the crystal, inter­molecular N—H⋯O hydrogen bonds link neighbouring mol­ecules into dimers generating R 2 2(8) ring motifs. These dimers are linked into ribbons along [101] via inter­molecular N—H⋯O hydrogen bonds, forming R 4 2(10) ring motifs.

5-Ethyl-4-phenyl-1H-pyrazol-3(2H)-one

“…The ethyl unit (C10B/C11B) in the molecule B is observed to be disordered over two positions with a site-occupancy ratio of 0.508 (5):0.492 (5). Bond lengths (Allen et al, 1987) and angles are within the normal ranges and are comparable to the related structures (Loh et al, 2010(Loh et al, , 2011Loh et al, 2010a,b).…”

AMHB: (Anti)aromaticity-Modulated Hydrogen Bonding

“…A survey of the online Cambridge Structural Database (WebCSD), in which H-bond-donor/-acceptor distances were compared, found that the average distance for 2a in five crystals of its derivatives − is 0.147 Å shorter (2.703(2) vs 2.850(4) Å, see Figure a) than for 2a ′ in 12 crystal structures. − Conversely, the average N···N distance in 3a derivatives in three crystal structures − is 0.110 Å longer (3.013(3) vs 2.903(3), see Figure b) than 3a ′ derivatives in five crystal structures. − These observations offer strong experimental support for the notion of aromaticity assisted H-bonding and aromaticity disrupted H-bonding in the cases of 2a and 3a , respectively.…”

β-Keto esters from ketones and ethyl chloroformate: a rapid, general, efficient synthesis of pyrazolones and their antimicrobial, in silico and in vitro cytotoxicity studies

“…In the similar way, the chemical shifts of all the other compounds have been assigned and are included in the experimental part. Some of the compounds 4 , 7 , 16 , 21 , 23 and 24 have been crystallized and subjected to the single crystal X-ray diffraction studies [68-75] and are available in the literature (Ortep plots are included in the Additional file 1); particularly, sample 4 has been crystallized as both in keto form and enol form. All the above discussions clearly revealed the formation of the desired products.…”