Ethyl 3,7-dichloro­quinoline-8-carboxyl­ate

Fengxia Zhu; Li-Tao An; Min Xia; Jian-Feng Zhou

doi:10.1107/S1600536808034995

. 2008 Oct 31;64(Pt 11):o2241. doi: 10.1107/S1600536808034995

Ethyl 3,7-dichloroquinoline-8-carboxylate

Fengxia Zhu ^a, Li-Tao An ^a,^*, Min Xia ^a, Jian-Feng Zhou ^a

PMCID: PMC2959780 PMID: 21581095

Abstract

The title compound, C₁₂H₉Cl₂NO₂, was prepared by the esterification of 3,7-dichloroquinoline-8-carboxylic acid with triethyl phosphite. The crystal structure is stabilized by aromatic π–π stacking between the benzene and the pyridine rings of neighbouring molecules [centroid–centroid distances = 3.716 (2) and 3.642 (2) Å]. In addition, weak intermolecular C—H⋯N hydrogen bonds are present in the structure.

Related literature

For the use of 3,7-dichloroquinoline-8-carboxylic acid as a herbicide, see: Nuria et al. (1997 ▶); Pornprom et al. (2006 ▶); Sunohara & Matsumoto (2004 ▶); Tresch & Grossmann (2002 ▶). For the usual preparative route, see: Yang et al. (2002 ▶). For related complexes, see: An et al. (2008 ▶); Che et al. (2005 ▶); Guo (2008 ▶); Li et al. (2008 ▶); Turel et al. (2004 ▶); Zhang et al. (2007 ▶). For 3,7-dichloroquinoline-8-carboxylic acid derivatives, see: Liang et al. (2006 ▶);

Experimental

Crystal data

C₁₂H₉Cl₂NO₂
M _r = 270.10
Tetragonal,
a = 25.4806 (3) Å
c = 7.3497 (2) Å
V = 4771.87 (15) Å³
Z = 16
Mo Kα radiation
μ = 0.53 mm⁻¹
T = 296 (2) K
0.10 × 0.08 × 0.06 mm

Data collection

Bruker SMART APEX2 diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 1999 ▶) T _min = 0.950, T _max = 0.969
19332 measured reflections
2750 independent reflections
1625 reflections with I > 2σ(I)
R _int = 0.045

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.117
S = 1.05
2750 reflections
155 parameters
H-atom parameters constrained
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXS97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808034995/lx2075sup1.cif

e-64-o2241-sup1.cif^{(15.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808034995/lx2075Isup2.hkl

e-64-o2241-Isup2.hkl^{(135.3KB, 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
C11—H11A⋯N1ⁱ	0.97	2.46	3.299 (3)	145

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was supported financially by Jiangsu Key Laboratory for the Chemistry of Low-dimensional Materials.

supplementary crystallographic information

Comment

Quinclorac (3,7-dichloroquinoline-8-carboxylic acid) is one of the most effective herbicides (Nuria et al., 1997; Pornprom et al., 2006; Sunohara & Matsumoto, 2004; Tresch & Grossmann, 2002). Usually, it was prepared via Skraup cyclization from 2-methyl-3- chloroaniline, followed by chlorination and oxidation (Yang et al., 2002). Furthermore, quinolinecarboxylates can chelate to metal atoms, forming the complexes, such as trans-Dimethanolbis(quinoline-8-carboxylato-κ²N,O)- cobalt(II) (Che et al.,2005),catena-Poly[nickel(II)-bis(µ-3,7-dichloroquinoline-8-χarboxylato-κ³N,O:O')] (Zhang et al., 2007), catena-Poly[cobalt(II)-bis (l-3,7-dichloroquinoline-8-carboxylato-κ³N,O:O')] (Li et al., 2008). More recently, we also have reported a Zinc-quinclorac complex (An et al., 2008) and quinclorac (Guo, 2008). But the derivatives of 3,7-dichloroquinoline-8-carboxylic acid have been less reported (Liang et al., 2006). Here we report the crystal structure of the title compound, ethyl 3,7-dichloroquinoline-8-carboxylate (I) (Fig. 1).

In the title compound (I), as shown in Fig. 1, the plane (O1—C10—O2—C11) is nearly vertical to the quinoline ring, in which the dihedral angel is 86.6 (1). The quinoline unit is essentially planar, with a mean deviation of 0.007 (2) Å from the least-squares plane defined by the ten constituent atoms. The molecular packing (Fig. 2) is stabilized by aromatic π—π stackings between the benzene and the pyridine rings of the adjacent molecules. The Cg1···Cg2ⁱⁱ and Cg1···Cg2ⁱⁱⁱ distances are 3.716 (2) and 3.642 (2) Å (Fig. 2; Cg1 and Cg2 are the centroids of the C1/C2/C3/C4/C9/C8 benzene ring and the N1/C7/C6/C5/C9/C8 pyridine ring, respectively, symmetry code as in Fig. 2). The crystal structure is further stabilized by intermolecular C11—H11A···Nⁱ hydrogen bonds (Fig. 2 and Table 1; symmetry code as in Fig. 2).

Experimental

Ethyl 3,7-dichloroquinoline-8-carboxylate was obtained from the reaction of 3,7-dichloroquinoline-8-carboxylic acid with triethyl phosphite in refluxing condition. After recrystallization from ethanol, then it was dissolved the mixture of acetone/petroleum ether (1:4, V/V). The suitable single-crystal for X-ray analysis was obtained by slow evaporation.