5-Methyl-2-phenyl-2H-pyrazol-3-ol

Qiang Wang; Yi Zhang; Rong Wang; Yi-Lin Yang; Feng Zhi

doi:10.1107/S1600536808028559

. 2008 Sep 13;64(Pt 10):o1924. doi: 10.1107/S1600536808028559

5-Methyl-2-phenyl-2H-pyrazol-3-ol

Qiang Wang ^a, Yi Zhang ^a, Rong Wang ^a, Yi-Lin Yang ^a,^*, Feng Zhi ^b,^*

PMCID: PMC2959372 PMID: 21201132

Abstract

The title compound, C₁₀H₁₀N₂O, known as Edaravone (MCI-186), was crystallized from methanol. The two independent molecules in the asymmetric unit are linked through an O—H⋯O hydrogen bond. One molecule adopts a ketone form, while the other adopts an enol form. In the crystal structure, molecules are linked through intermolecular N—H⋯O hydrogen bonds, forming chains running along the b axis.

Related literature

For background to the compound, see: Watanabe et al. (1994 ▶); The Edaravone Acute Infarction Study Group (2003 ▶). For bond-length data, see: Allen et al. (1987 ▶). ▶

Experimental

Crystal data

C₁₀H₁₀N₂O
M _r = 174.20
Monoclinic,
a = 10.336 (2) Å
b = 11.154 (2) Å
c = 15.863 (3) Å
β = 95.157 (3)°
V = 1821.4 (6) Å³
Z = 8
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 298 (2) K
0.23 × 0.23 × 0.20 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.981, T _max = 0.983
10551 measured reflections
3923 independent reflections
2894 reflections with I > 2σ(I)
R _int = 0.025

Refinement

R[F ² > 2σ(F ²)] = 0.040
wR(F ²) = 0.106
S = 1.04
3923 reflections
243 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.14 e Å⁻³

Data collection: SMART (Bruker, 2002 ▶); cell refinement: SAINT (Bruker, 2002 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808028559/sg2259sup1.cif

e-64-o1924-sup1.cif^{(18.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808028559/sg2259Isup2.hkl

e-64-o1924-Isup2.hkl^{(196.2KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2A⋯N4ⁱ	0.907 (9)	1.904 (10)	2.7999 (17)	169.4 (17)
O2—H2B⋯O1	0.870 (9)	1.618 (10)	2.4813 (15)	170.9 (19)

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Symmetry code: (i) Inline graphic .

supplementary crystallographic information

Comment

Edaravone (5-methyl-2-phenyl-2H-pyrazol-3-ol, MCI-186) is a free-radical scavenger that was approved by the Ministry of Health, Labor, and Welfare of Japan in 2001, and is now widely used for the treatment of acute cerebral infarction (Watanabe et al.., 1994; The Edaravone Acute Infarction Study Group, 2003). We report in this paper the crystal structure of the compound, (I).

The compound consists of two independent molecules (Fig. 1), which are linked through an intramolecular O2—H2B···O1 hydrogen bond (Table 1). One molecule adopts a ketone form, while the other adopts an enol form. In the ketone molecule, the dihedral angle between the C1–C6 benzene ring and the N1/N2/C9/C8/C7 ring is 22.9 (2)°. In the enol molecule, the dihedral angle between the C11–C16 benzene ring and the N3/N4/C19/C18/C17 ring is 34.3 (2)°. In the compound, all the bond lengths are within normal ranges (Allen et al., 1987). The bond length of C17—O2 [1.325 (2) Å] is longer than that of C7—O1 [1.260 (2) Å], which is caused by the enol form.

In the crystal structure, molecules are linked through intermolecular N–H···O hydrogen bonds (Table 1), forming chains running along the b axis (Fig. 2).

Experimental

The crystal of the compound was recrystallized by edaravone in methanol.