organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

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

aDepartment of Neurosurgery, Third Affiliated Hospital of Soochow University, Changzhou 213003, People's Republic of China, and bLaboratory of Neuronal Injury and Protection, Third Affiliated Hospital of Soochow University, Changzhou 213003, People's Republic of China
*Correspondence e-mail: czfph@yahoo.com.cn, danielzhif@yahoo.com.cn

(Received 28 August 2008; accepted 6 September 2008; online 13 September 2008)

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[Watanabe, T., Yuki, S., Egawa, M. & Nishi, H. (1994). J. Pharmacol. Exp. Ther. 268, 1597-1604.]); The Edaravone Acute Infarction Study Group (2003[The Edaravone Acute Infarction Study Group (2003). Cerebrovasc. Dis. 15, 222-229.]). For bond-length data, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]).[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]

[Scheme 1]

Experimental

Crystal data
  • C10H10N2O

  • Mr = 174.20

  • Monoclinic, P 21 /c

  • 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[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.981, Tmax = 0.983

  • 10551 measured reflections

  • 3923 independent reflections

  • 2894 reflections with I > 2σ(I)

  • Rint = 0.025

Refinement
  • R[F2 > 2σ(F2)] = 0.040

  • wR(F2) = 0.106

  • S = 1.04

  • 3923 reflections

  • 243 parameters

  • 2 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.17 e Å−3

  • Δρmin = −0.14 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA 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)
Symmetry code: (i) x, y-1, z.

Data collection: SMART (Bruker, 2002[Bruker (2002). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2002[Bruker (2002). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

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).

Related literature top

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

Experimental top

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

Refinement top

H2A and H2B were located in a difference Fourier map and refined isotropically, with N–H and O–H distances restrained to 0.90 (1) and 0.85 (1) Å, and with Uiso(H) set to 0.08 Å2. Other H atoms were constrained to idealized geometries, with C–H = 0.93–0.96 Å, and with Uiso(H) set to 1.2Ueq(C) and 1.5Ueq(methyl C).

Computing details top

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); 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 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The structure of (I) at the 30% probability level. Intramolecular hydrogen bonds are shown as dashed lines.
[Figure 2] Fig. 2. Molecular packing of (I), viewed along the a axis. Intermolecular hydrogen bonds are shown as dashed lines.
5-Methyl-2-phenyl-2H-pyrazol-3-ol top
Crystal data top
C10H10N2OF(000) = 736
Mr = 174.20Dx = 1.271 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3931 reflections
a = 10.336 (2) Åθ = 2.3–29.0°
b = 11.154 (2) ŵ = 0.09 mm1
c = 15.863 (3) ÅT = 298 K
β = 95.157 (3)°Block, colorless
V = 1821.4 (6) Å30.23 × 0.23 × 0.20 mm
Z = 8
Data collection top
Bruker SMART CCD area-detector
diffractometer
3923 independent reflections
Radiation source: fine-focus sealed tube2894 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.025
ω scanθmax = 27.0°, θmin = 2.2°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 1311
Tmin = 0.981, Tmax = 0.983k = 1314
10551 measured reflectionsl = 2018
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.040H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.106 w = 1/[σ2(Fo2) + (0.0428P)2 + 0.3053P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max < 0.001
3923 reflectionsΔρmax = 0.17 e Å3
243 parametersΔρmin = 0.14 e Å3
2 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0087 (12)
Crystal data top
C10H10N2OV = 1821.4 (6) Å3
Mr = 174.20Z = 8
Monoclinic, P21/cMo Kα radiation
a = 10.336 (2) ŵ = 0.09 mm1
b = 11.154 (2) ÅT = 298 K
c = 15.863 (3) Å0.23 × 0.23 × 0.20 mm
β = 95.157 (3)°
Data collection top
Bruker SMART CCD area-detector
diffractometer
3923 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
2894 reflections with I > 2σ(I)
Tmin = 0.981, Tmax = 0.983Rint = 0.025
10551 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0402 restraints
wR(F2) = 0.106H atoms treated by a mixture of independent and constrained refinement
S = 1.04Δρmax = 0.17 e Å3
3923 reflectionsΔρmin = 0.14 e Å3
243 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.76081 (11)0.23408 (9)0.09473 (8)0.0652 (3)
O20.63865 (11)0.42520 (9)0.07652 (7)0.0577 (3)
N10.80235 (11)0.03414 (9)0.07061 (8)0.0469 (3)
N20.76341 (13)0.04917 (10)0.00921 (8)0.0516 (3)
N30.69321 (11)0.62596 (9)0.06745 (7)0.0418 (3)
N40.76998 (12)0.70070 (10)0.02382 (8)0.0490 (3)
C10.91015 (13)0.01075 (12)0.12978 (9)0.0457 (3)
C20.92942 (16)0.07840 (15)0.20276 (10)0.0603 (4)
H20.87220.13990.21310.072*
C31.03427 (19)0.05375 (19)0.26009 (12)0.0768 (5)
H31.04810.09970.30900.092*
C41.1181 (2)0.0372 (2)0.24600 (13)0.0814 (6)
H41.18810.05360.28530.098*
C51.09872 (17)0.10395 (18)0.17403 (14)0.0755 (5)
H51.15570.16610.16470.091*
C60.99550 (15)0.08041 (15)0.11475 (11)0.0597 (4)
H60.98370.12550.06530.072*
C70.73814 (14)0.14046 (12)0.05144 (10)0.0486 (4)
C80.65398 (16)0.11675 (14)0.02083 (10)0.0566 (4)
H80.59700.17130.04860.068*
C90.66976 (15)0.00076 (14)0.04331 (10)0.0536 (4)
C100.6047 (2)0.07170 (17)0.11335 (11)0.0760 (5)
H10A0.65860.07440.15960.114*
H10B0.52270.03590.13210.114*
H10C0.59080.15170.09370.114*
C110.61818 (14)0.67394 (12)0.12999 (8)0.0441 (3)
C120.49765 (15)0.62664 (14)0.14196 (10)0.0545 (4)
H120.46550.56110.11040.065*
C130.42556 (18)0.67832 (19)0.20167 (12)0.0755 (6)
H130.34500.64620.21080.091*
C140.4708 (2)0.7760 (2)0.24752 (12)0.0860 (7)
H140.42050.81100.28660.103*
C150.5904 (2)0.82150 (17)0.23553 (11)0.0799 (6)
H150.62130.88760.26690.096*
C160.66614 (18)0.77067 (13)0.17737 (10)0.0584 (4)
H160.74820.80120.17030.070*
C170.70530 (13)0.51085 (11)0.04194 (9)0.0430 (3)
C180.79096 (15)0.51055 (13)0.01882 (10)0.0526 (4)
H180.81900.44450.04790.063*
C190.82756 (15)0.62954 (13)0.02813 (10)0.0510 (4)
C200.91583 (19)0.68181 (17)0.08846 (13)0.0794 (6)
H20A0.90600.76740.09000.119*
H20B0.89380.64960.14400.119*
H20C1.00420.66190.07000.119*
H2A0.7692 (17)0.1287 (9)0.0208 (11)0.080*
H2B0.6823 (16)0.3585 (12)0.0773 (12)0.080*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0757 (7)0.0322 (5)0.0864 (8)0.0043 (5)0.0001 (6)0.0043 (5)
O20.0673 (7)0.0311 (5)0.0772 (7)0.0007 (5)0.0205 (6)0.0059 (5)
N10.0531 (7)0.0283 (6)0.0577 (7)0.0011 (5)0.0031 (6)0.0011 (5)
N20.0640 (8)0.0310 (6)0.0581 (7)0.0018 (5)0.0030 (6)0.0012 (5)
N30.0493 (6)0.0298 (6)0.0476 (6)0.0024 (5)0.0114 (5)0.0017 (5)
N40.0588 (8)0.0324 (6)0.0582 (7)0.0021 (5)0.0185 (6)0.0015 (5)
C10.0456 (8)0.0362 (7)0.0551 (8)0.0040 (6)0.0031 (6)0.0098 (6)
C20.0646 (10)0.0555 (10)0.0603 (10)0.0023 (8)0.0035 (8)0.0003 (8)
C30.0793 (13)0.0876 (14)0.0607 (11)0.0113 (11)0.0084 (9)0.0024 (10)
C40.0653 (12)0.1020 (16)0.0736 (12)0.0004 (11)0.0122 (10)0.0206 (12)
C50.0569 (10)0.0769 (12)0.0919 (14)0.0161 (9)0.0016 (10)0.0187 (11)
C60.0567 (9)0.0531 (9)0.0687 (10)0.0082 (7)0.0024 (8)0.0050 (8)
C70.0513 (8)0.0310 (7)0.0640 (9)0.0023 (6)0.0082 (7)0.0075 (7)
C80.0597 (9)0.0453 (9)0.0635 (10)0.0101 (7)0.0019 (8)0.0127 (7)
C90.0599 (9)0.0477 (9)0.0523 (8)0.0013 (7)0.0006 (7)0.0069 (7)
C100.0886 (13)0.0739 (12)0.0622 (10)0.0045 (10)0.0120 (9)0.0032 (9)
C110.0544 (8)0.0339 (7)0.0447 (7)0.0122 (6)0.0093 (6)0.0067 (6)
C120.0524 (9)0.0531 (9)0.0586 (9)0.0130 (7)0.0090 (7)0.0135 (7)
C130.0686 (11)0.0872 (14)0.0749 (12)0.0326 (10)0.0304 (9)0.0286 (11)
C140.1171 (18)0.0853 (15)0.0612 (11)0.0533 (13)0.0383 (12)0.0143 (11)
C150.1298 (18)0.0540 (11)0.0579 (10)0.0258 (11)0.0198 (11)0.0063 (8)
C160.0812 (11)0.0414 (8)0.0537 (9)0.0066 (8)0.0121 (8)0.0019 (7)
C170.0495 (8)0.0285 (6)0.0511 (7)0.0027 (6)0.0048 (6)0.0015 (6)
C180.0622 (9)0.0379 (8)0.0597 (9)0.0065 (7)0.0166 (7)0.0068 (7)
C190.0538 (8)0.0432 (8)0.0580 (9)0.0022 (6)0.0163 (7)0.0002 (7)
C200.0868 (13)0.0683 (12)0.0901 (13)0.0032 (10)0.0467 (11)0.0008 (10)
Geometric parameters (Å, º) top
O1—C71.260 (2)C8—C91.356 (2)
O2—C171.325 (2)C8—H80.9300
O2—H2B0.870 (9)C9—C101.485 (2)
N1—C71.379 (2)C10—H10A0.9600
N1—N21.380 (2)C10—H10B0.9600
N1—C11.415 (2)C10—H10C0.9600
N2—C91.340 (2)C11—C161.381 (2)
N2—H2A0.907 (9)C11—C121.382 (2)
N3—C171.355 (2)C12—C131.383 (2)
N3—N41.379 (2)C12—H120.9300
N3—C111.418 (2)C13—C141.369 (3)
N4—C191.323 (2)C13—H130.9300
C1—C61.381 (2)C14—C151.365 (3)
C1—C21.381 (2)C14—H140.9300
C2—C31.378 (2)C15—C161.384 (2)
C2—H20.9300C15—H150.9300
C3—C41.366 (3)C16—H160.9300
C3—H30.9300C17—C181.366 (2)
C4—C51.362 (3)C18—C191.392 (2)
C4—H40.9300C18—H180.9300
C5—C61.383 (2)C19—C201.498 (2)
C5—H50.9300C20—H20A0.9600
C6—H60.9300C20—H20B0.9600
C7—C81.400 (2)C20—H20C0.9600
C17—O2—H2B109.5 (13)C9—C10—H10B109.5
C7—N1—N2108.62 (11)H10A—C10—H10B109.5
C7—N1—C1129.74 (12)C9—C10—H10C109.5
N2—N1—C1120.42 (11)H10A—C10—H10C109.5
C9—N2—N1107.91 (11)H10B—C10—H10C109.5
C9—N2—H2A124.3 (11)C16—C11—C12120.50 (14)
N1—N2—H2A120.4 (12)C16—C11—N3118.91 (13)
C17—N3—N4110.49 (11)C12—C11—N3120.57 (13)
C17—N3—C11129.60 (11)C11—C12—C13118.88 (17)
N4—N3—C11119.90 (10)C11—C12—H12120.6
C19—N4—N3105.14 (11)C13—C12—H12120.6
C6—C1—C2120.05 (14)C14—C13—C12121.09 (19)
C6—C1—N1119.90 (13)C14—C13—H13119.5
C2—C1—N1120.05 (13)C12—C13—H13119.5
C3—C2—C1119.32 (17)C15—C14—C13119.52 (17)
C3—C2—H2120.3C15—C14—H14120.2
C1—C2—H2120.3C13—C14—H14120.2
C4—C3—C2120.86 (18)C14—C15—C16120.93 (19)
C4—C3—H3119.6C14—C15—H15119.5
C2—C3—H3119.6C16—C15—H15119.5
C5—C4—C3119.69 (17)C11—C16—C15119.06 (18)
C5—C4—H4120.2C11—C16—H16120.5
C3—C4—H4120.2C15—C16—H16120.5
C4—C5—C6120.84 (18)O2—C17—N3119.60 (12)
C4—C5—H5119.6O2—C17—C18133.19 (13)
C6—C5—H5119.6N3—C17—C18107.21 (12)
C1—C6—C5119.23 (17)C17—C18—C19105.80 (12)
C1—C6—H6120.4C17—C18—H18127.1
C5—C6—H6120.4C19—C18—H18127.1
O1—C7—N1122.01 (13)N4—C19—C18111.36 (13)
O1—C7—C8132.37 (13)N4—C19—C20119.87 (13)
N1—C7—C8105.62 (12)C18—C19—C20128.74 (14)
C9—C8—C7108.35 (13)C19—C20—H20A109.5
C9—C8—H8125.8C19—C20—H20B109.5
C7—C8—H8125.8H20A—C20—H20B109.5
N2—C9—C8109.29 (14)C19—C20—H20C109.5
N2—C9—C10119.47 (14)H20A—C20—H20C109.5
C8—C9—C10131.23 (15)H20B—C20—H20C109.5
C9—C10—H10A109.5
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···N4i0.91 (1)1.90 (1)2.7999 (17)169 (2)
O2—H2B···O10.87 (1)1.62 (1)2.4813 (15)171 (2)
Symmetry code: (i) x, y1, z.

Experimental details

Crystal data
Chemical formulaC10H10N2O
Mr174.20
Crystal system, space groupMonoclinic, P21/c
Temperature (K)298
a, b, c (Å)10.336 (2), 11.154 (2), 15.863 (3)
β (°) 95.157 (3)
V3)1821.4 (6)
Z8
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.23 × 0.23 × 0.20
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.981, 0.983
No. of measured, independent and
observed [I > 2σ(I)] reflections
10551, 3923, 2894
Rint0.025
(sin θ/λ)max1)0.639
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.106, 1.04
No. of reflections3923
No. of parameters243
No. of restraints2
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.17, 0.14

Computer programs: SMART (Bruker, 2002), SAINT (Bruker, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···N4i0.907 (9)1.904 (10)2.7999 (17)169.4 (17)
O2—H2B···O10.870 (9)1.618 (10)2.4813 (15)170.9 (19)
Symmetry code: (i) x, y1, z.
 

References

First citationAllen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.  CrossRef Web of Science Google Scholar
First citationBruker (2002). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationSheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationThe Edaravone Acute Infarction Study Group (2003). Cerebrovasc. Dis. 15, 222–229.  Web of Science CrossRef PubMed Google Scholar
First citationWatanabe, T., Yuki, S., Egawa, M. & Nishi, H. (1994). J. Pharmacol. Exp. Ther. 268, 1597–1604.  CAS PubMed Web of Science Google Scholar

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