2-(4-Chloro­phen­yl)chromen-4-one

Shailja Singh; Manavendra K Singh; Alka Agarwal; Satish K Awasthi

doi:10.1107/S1600536811043832

. 2011 Nov 5;67(Pt 12):o3163. doi: 10.1107/S1600536811043832

2-(4-Chlorophenyl)chromen-4-one

Shailja Singh ^a, Manavendra K Singh ^b, Alka Agarwal ^b, Satish K Awasthi ^a,^*

PMCID: PMC3238834 PMID: 22199687

Abstract

The title compound, C₁₅H₉ClO₂, is a synthetic flavonoid obtained by the cyclization of 3-(4-chlorophenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one. The 4-chlorophenyl ring is twisted at an angle of 11.54° with respect to the chromen-4-one skeleton. In the crystal, pairs of molecules are interconnected by weak Cl⋯Cl interactions [3.3089 (10) Å] forming dimmers which are further peripherally connected through intermolecular C—H⋯O hydrogen bonds.

Related literature

For general features and crystal structures of flavanoids, see: Tim Cushnie & Lamb (2005 ▶); Wera et al. (2011 ▶). For crystal structures of small molecules, see: Singh, Agarwal & Awasthi (2011 ▶); Singh, Singh et al. (2011 ▶). For the synthesis, see: Migrdichian (1957 ▶); Awasthi et al. (2009 ▶); Shah et al. (1955 ▶). For intermolecular interactions and bond lengths and angles, see: Reddy et al. (2006 ▶); Wang et al. (2010 ▶); Desiraju & Steiner (1999 ▶); Waller et al. (2003 ▶); Allen et al. (1987 ▶).

Experimental

Crystal data

C₁₅H₉ClO₂
M _r = 256.67
Monoclinic,
a = 22.1564 (16) Å
b = 3.8745 (2) Å
c = 26.7728 (18) Å
β = 95.524 (6)°
V = 2287.6 (3) Å³
Z = 8
Mo Kα radiation
μ = 0.32 mm⁻¹
T = 293 K
0.40 × 0.39 × 0.38 mm

Data collection

Oxford Xcalibur Eos diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 ▶) T _min = 0.938, T _max = 0.941
8152 measured reflections
2249 independent reflections
1910 reflections with I > 2σ(I)
R _int = 0.037
Standard reflections: 0

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.119
S = 1.10
2249 reflections
163 parameters
H-atom parameters constrained
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811043832/zj2023sup1.cif

e-67-o3163-sup1.cif^{(16.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811043832/zj2023Isup2.hkl

e-67-o3163-Isup2.hkl^{(110.7KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811043832/zj2023Isup3.cml

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—H11⋯O2ⁱ	0.93	2.64	3.345 (3)	134 (1)

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Symmetry code: (i) Inline graphic .

Acknowledgments

SKA is grateful to the Department of Science and Technology (Scheme No. SR/SO BB-65/2003 ) and the University of Delhi, India, for financial assistance. The authors are very grateful to the University Sophisticated Instrument Center (USIC), University of Delhi, India, for providing the single-crystal X-ray diffractometer facility.

supplementary crystallographic information

Comment

The term flavonoid generally includes a group of natural products containing a C6—C3—C6 carbon skeleton or more specifically phenylbenzopyran functionality in the molecule. Flavones (flavus = yellow), a class of the flavonoids mainly found in cereals and herbs. Flavanoids exhibit a wide range of biological activities such as antibacterial, anti-inflammatory, antioxidants, antifungal, antitumour and antimalarial (Tim Cushnie & Lamb 2005). Recently, few flavanoids have also been characterized in solid state (Wera et al., 2011). Continuing our ongoing work on antimalarials (Awasthi et al., 2009) and crystal structure of small molecules (Singh, Agarwal & Awasthi, 2011; Singh, Singh et al., 2011), here we wish to report the crystal structure of 2-(4-chlorophenyl)chromen-4-one.

In the title compound (Fig. 1),the bond lengths and bond angles are usual and are comparable with the analogues structure of 2-phenyl-4H-chromen-4-one (flavone) reported earlier (Allen et al., 1987; Waller et al., 2003). The 4-chlorophenyl ring in the molecule is twisted at an angle of 11.54° relative to the chromen-4-one skeleton confirming nearly planner structure. The centroid–centroid distance between two parallel chromone ring in the molecule is 3.87 Å. Further, it is evident from the crystal packing structure (Fig. 2) that 8 molecules are present in a unit cell and adjacent chromone units are parallel in a given column, thus forming a herringbone type pattern. Moreover,crystal packing in the molecule is stabilized by weaker intermolecular hydrogen bonding C11—H11—O2 [D = 3.34 (3) Å] which is very well supported by earlier findings (Desiraju & Steiner, 1999). Further, weak interaction among atoms in molecule such as Cl1—Cl1 (x, -1 + y, 1/2 - z) [3.30 Å] (Reddy et al.,2006) and C8—H8—H8—C8 [2.26 Å](Wang et al., 2010) are also responsible for stability in the crystal packing. Further, intermolecular Cl1—Cl1 short interaction forms a dimeric unit which are further peripherically links to six other molecules through C—H—O and C—H—H—C interactions.

Experimental

The synthesis of the title compound was carried out in two steps according to the published procedure. (Migrdichian 1957; Awasthi et al., 2009). In the first step, an aqueous solution of sodium hydroxide (10% w/v, 10 ml) was added to a solution of 2-hydroxyacetophenone (1.77 g m, 10 mmol) and 4-chlorobenzaldehyde (1.73 g m, 10 mmol) in minimum amount of methanol (3–5 ml) at ice cooled flask. The reaction mixture was allowed to draw closer to room temperature and stirred for 18–20 h yielded a yellow solid. The completion of the reaction was monitored by thin layer chromatography. After completion of the reaction, the mixture was neutralized with 10% hydrochloric acid in water. The compound was characterized by ¹H NMR, ¹³C NMR, FT–IR and EI–MS.

In second step, the cyclization was carried out according to published procedure (Shah et al., 1955). Briefly, 3-(4-chlorophenyl)-1-(2-hydroxyphenyl)propenone (40 mg, 0.12 mmol) & SeO₂ (39 mg, 0.35 mmol) were added to dry amyl alcohol (30 ml) and the mixture was heated in an oil bath at 140–150 °C so that the entire compound was completely dissolved in the solvent. The reaction mixture was refluxed for 12 h and completion of the reaction was monitored by TLC. The reaction mixture was then filtered and dried in vacuum and purified by silica gel column using (Pet. ether: EtOAc, 2:3) as eluent. The recrystalliation of an isolated compound from PE/ethylacetate to afford 2-(4-chlorophenyl)chromen-4-one (10 mg, 20.1%) as white solid, m.p 177–178°C. R_f 0.6 (PE; EtOAc, 2:3). FT–IR ν_max (KBr) cm^-1: 1651 (C═O), 1606 and 1510 (C═C aromatic), 1263 (C—O); ¹H NMR (300 Mz, CDCl₃) p.p.m.: δ 6.63 (1H, s, H-3, pyrone ring), δ 7.32–7.48 (4H, m, Ar-H, H'-5, H'-6, H'-7, H'-8), 7.20 (2H, dd, J = 2.4 Hz, H'-5, H'-3), 7.28 (2H, dd, J = 2.1 Hz, H'-2, H'-6), ¹³C NMR (300 Mz, CDCl₃) ppm: EI–MS: m/z 255 [M+].

For crystallization 5 mg of compound dissolved in 5 ml mixture of Petroleum ether/ethylacetate (80:20) and left for several days at ambient temperature which yielded fine needle shape crystals.