Ethyl 5-amino-1-(4-chloro-2-nitro­phen­yl)-1H-pyrazole-4-carboxyl­ate

Muhammad Zia-ur-Rehman; Mark R J Elsegood; Jamil Anwar Choudary; Muhammad Fasih Ullah; Hamid Latif Siddiqui

doi:10.1107/S1600536809000488

. 2009 Jan 10;65(Pt 2):o275–o276. doi: 10.1107/S1600536809000488

Ethyl 5-amino-1-(4-chloro-2-nitrophenyl)-1H-pyrazole-4-carboxylate

Muhammad Zia-ur-Rehman ^a,^*, Mark R J Elsegood ^b, Jamil Anwar Choudary ^c, Muhammad Fasih Ullah ^c, Hamid Latif Siddiqui ^c

PMCID: PMC2968147 PMID: 21581889

Abstract

In the molecule of the title compound, C₁₂H₁₁ClN₄O₄, the pyrazole ring is coplanar with the amino and ethoxycarbonyl groups within 0.026 (2) and 0.105 (2) Å, respectively. The C ₆ ring of the 4-chloro-2-nitrophenyl group is twisted by 53.58 (4)° relative to the plane of the pyrazole ring. The planar structure of the pyrazole ring is stabilized by an intramolecular N—H⋯O hydrogen bond between its substituents. Neighbouring molecules are linked through intermolecular N—H⋯N and N—H⋯O hydrogen bonds, giving rise to one-dimensional tapes along the b axis. Molecules in the chain are linked to those of an adjacent chain through weak C—H⋯O interactions, forming a three-dimensional network.

Related literature

For the biological activity of pyrazole and its derivatives, see: Iovu et al. (2003 ▶); Mahajan et al. (1991 ▶); related literature, see: Akhtar et al. (2008 ▶); Baraldi et al. (1998 ▶); Bruno et al. (1990 ▶); Cottineau et al. (2002 ▶); Smith et al. (2001 ▶). For the use of pyrazole-based ligands in investigating the structure–activity relationship of the active site of metalloproteins, see: Dardari et al. (2006 ▶), and in the preparation of commercially important dyestuffs, see: Baroni & Kovyrzina (1961 ▶); Neunhoeffer et al. (1959 ▶). For the synthesis and biological evaluation of heterocyclic compounds, see: Akhtar et al. (2008 ▶); Zia-ur-Rehman et al. (2006 ▶, 2008 ▶).

Experimental

Crystal data

C₁₂H₁₁ClN₄O₄
M _r = 310.70
Monoclinic,
a = 8.5899 (8) Å
b = 10.2413 (9) Å
c = 15.6633 (14) Å
β = 96.5415 (13)°
V = 1369.0 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.30 mm⁻¹
T = 150 (2) K
0.79 × 0.27 × 0.09 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2007 ▶) T _min = 0.797, T _max = 0.973
15944 measured reflections
4189 independent reflections
3588 reflections with I > 2σ(I)
R _int = 0.022

Refinement

R[F ² > 2σ(F ²)] = 0.034
wR(F ²) = 0.096
S = 1.04
4189 reflections
197 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.44 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: SAINT (Bruker, 2006 ▶); 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: SHELXTL and local programs.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809000488/bt2841sup1.cif

e-65-0o275-sup1.cif^{(18.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809000488/bt2841Isup2.hkl

e-65-0o275-Isup2.hkl^{(205.3KB, 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
N4—H4A⋯O3	0.866 (16)	2.328 (16)	2.9383 (13)	127.7 (12)
N4—H4A⋯O2ⁱ	0.866 (16)	2.610 (15)	3.1356 (13)	120.1 (12)
N4—H4B⋯N3ⁱ	0.871 (15)	2.153 (16)	3.0074 (13)	166.8 (14)

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Symmetry code: (i) Inline graphic .

Acknowledgments

The authors are grateful to the Pakistan Council of Scientific & Industrial Research Laboratories, Lahore, Pakistan, for the provision of necessary chemicals.

supplementary crystallographic information

Comment

Pyrazole and its derivatives represent one of the most important classes of organic heterocyclic compounds, possessing a wide spectrum of biological activities such as antibacterial, fungicidal (Iovu et al., 2003), herbicidal (Mahajan et al.,1991) and antiviral (Baraldi et al., 1998) activities. Some of their derivatives have been reported to possess significant antiarrhythmic & sedative (Bruno et al., 1990), hypoglycemic (Cottineau et al., 2002) and anti-inflammatory (Smith et al., 2001) activities. In addition, pyrazole based ligands have also been used to investigate the structure-activity relationship of the active site of metalloproteins (Dardari et al., 2006) and for the preparation of commercially important dyestuffs (Baroni & Kovyrzina, 1961; Neunhoeffer et al.,1959). As part of our ongoing research on the synthesis and biological evaluation of heterocyclic compounds (Akhtar et al., 2008; Zia-ur-Rehman et al., 2006; Zia-ur-Rehman et al., 2008), crystal structure of the title compound, (I) was determined.

In I (Fig. 1) the pyrazole ring is approximately coplanar with the amino and ethyl carboxylate groups. The C₆ ring of the 4-chloro-2-nitro phenyl group is essentially planar and is twisted by 53.58 (4)° relative to the plane of the pyrazole ring about the C6—N2 bond. The planar structure of the pyrazole ring is stabilized by an intramolecular N—H···O hydrogen bond between the amino and ethyl carboxylate substituents (Table 1). Neighbouring molecules are linked through one N—H···N and one N—H···O intermolecular hydrogen bond giving rise to one-dimensional tapes along the b axis (Fig. 2, Table 1). The nitro group is twisted by 37.98 (4)° relative to the C₆ ring, driven by the desire to form the aforementioned H-bond. Each chain is cross-linked to the next through weak C–H···O interactions.

Experimental

A mixture of 5-amino-1-(4-chloro-2-nitrophenyl)-1H-pyrazole-4-carboxylic acid (3.05 g; 10.0 mmoles), phosphoric acid (0.196 g; 2.0 mmoles) and ethyl alcohol (100 ml) was refluxed for a period of five hours. The reaction mixture was then concentrated (to a volume of 20 ml) by slow distillation of ethanol followed by cooling and addition of cold water. The precipitated solid was then filtered, washed with cold water and dried. Crystals suitable for single-crystal X-ray diffraction were grown by slow evaporation of a solution of the title compound in a mixture of ethanol and water (85: 15); yield: 73.68%.