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

Tara Shahani; Hoong-Kun Fun; R Venkat Ragavan; V Vijayakumar; S Sarveswari

doi:10.1107/S160053681001696X

. 2010 May 15;66(Pt 6):o1357–o1358. doi: 10.1107/S160053681001696X

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

Tara Shahani ^a, Hoong-Kun Fun ^a,^*,^‡, R Venkat Ragavan ^b, V Vijayakumar ^b, S Sarveswari ^b

PMCID: PMC2979558 PMID: 21579442

Abstract

In the title compound, C₆H₁₀N₂O, the 2,3-dihydro-1H-pyrazole ring is approximately planar, with a maximum deviation of 0.013 (1) Å. Pairs of intermolecular N—H⋯O hydrogen bonds link neighboring molecules into dimers, generating R ₂ ²(8) ring motifs. These dimers are further linked into two-dimensional arrays parallel to the bc plane by intermolecular N—H⋯O hydrogen bonds. The crystal structure is further stabilized by C—H⋯π interactions.

Related literature

For the background to and the biological activity of 3-ethyl-4-methyl-1H-pyrazol-5-ol, see: Brogden (1986 ▶); Coersmeier et al. (1986); Gursoy et al. (2000 ▶); Ragavan et al. (2009 ▶, 2010 ▶); Watanabe et al. (1984 ▶); Kawai et al. (1997 ▶); Wu et al. (2002 ▶). For related structures, see: Shahani et al. (2009 ▶, 2010 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For reference bond-length data, see: Allen et al. (1987 ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₆H₁₀N₂O
M _r = 126.16
Monoclinic,
a = 8.374 (2) Å
b = 7.2881 (16) Å
c = 11.300 (3) Å
β = 109.955 (5)°
V = 648.3 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 K
0.52 × 0.16 × 0.09 mm

Data collection

Bruker APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.954, T _max = 0.992
10018 measured reflections
2745 independent reflections
2325 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.123
S = 1.14
2745 reflections
122 parameters
All H-atom parameters refined
Δρ_max = 0.52 e Å⁻³
Δρ_min = −0.35 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681001696X/wn2385sup1.cif

e-66-o1357-sup1.cif^{(15.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053681001696X/wn2385Isup2.hkl

e-66-o1357-Isup2.hkl^{(134.8KB, hkl)}

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

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

Cg1 is the centroid of the 1H-pyrazole ring (C1–C3/N1/N2).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N1⋯O1ⁱ	0.902 (15)	1.829 (15)	2.7267 (11)	174.0 (16)
N2—H1N2⋯O1ⁱⁱ	0.972 (14)	1.715 (14)	2.6777 (10)	169.9 (13)
C5—H5A⋯Cg1ⁱⁱⁱ	1.013 (13)	2.896 (15)	3.6749 (14)	134.2 (11)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

TSH and HKF thank Universiti Sains Malaysia (USM) for the Research University Golden Goose Grant (1001/PFIZIK/811012). VV is grateful to the DST-India for funding through the Young Scientist Scheme (Fast Track Proposal).

supplementary crystallographic information

Comment

Pyrazolone derivatives have a broad spectrum of biological activities as analgesic, antipyretic and anti-inflammatory therapeutical drugs (Brogden, 1986; Gursoy et al., 2000). A class of new pyrazolone compounds have been synthesized and reported to exhibit antibacterial and antifungal activities (Ragavan et al., 2010; Ragavan et al., 2009). A new pyrazolone derivative, edaravone (5-ethyl-4-methyl-1H-pyrazol-3(2H)-one), is being used as a drug in clinical practice for brain ischemia (Watanabe et al., 1984; Kawai et al., 1997) and it has also been found to be effective against myocardial ischemia (Wu et al., 2002).

In the crystal structure (Fig. 1), the 2,3-dihydro-1H-pyrazole ring (C1–C3/N1/N2) is approximately planar with a maximum deviation of 0.013 (1) Å for atoms N1 and N2 (but they are on opposite sides of the plane). The bond lengths (Allen et al., 1987) and angles are within normal ranges and comparable to those in closely related structures reported recently (Shahani et al., 2009; 2010).

In the crystal packing (Fig. 2), pairs of intermolecular N1—H1N1···O1 hydrogen bonds (Table 1) link neighboring molecules into dimers, generating R²₂(8) ring motifs (Bernstein et al., 1995). These dimers are further linked into 2D arrays parallel to the bc plane by intermolecular N2—H1N2···O1 hydrogen bonds (Table 1). The crystal structure is further stabilized by a C—H···π interaction (Table 1), involving the C1–C3/N1/N2 ring (centroid Cg1) .

Experimental

The compound 5-ethyl-4-methyl-1H-pyrazol-3(2H)-one has been synthesized using the method reported in the literature (Ragavan et al., 2009, 2010) and purified by column chromatography (MeOH: EtOAc, 1:99). It was recrystallised as a colourless solid, using ethanol. Mp: 496.4–507.1 K; MS calculated for C₆H₁₀N₂O: 126.15. Found: 128.0 (M+).