2-Chloro-N-[4-chloro-2-(2-chloro­benzo­yl)phen­yl]acetamide

Grzegorz Dutkiewicz; B P Siddaraju; H S Yathirajan; B Narayana; Maciej Kubicki

doi:10.1107/S1600536810003375

. 2010 Jan 30;66(Pt 2):o499. doi: 10.1107/S1600536810003375

2-Chloro-N-[4-chloro-2-(2-chlorobenzoyl)phenyl]acetamide

Grzegorz Dutkiewicz ^a, B P Siddaraju ^b, H S Yathirajan ^c, B Narayana ^d, Maciej Kubicki ^a,^*

PMCID: PMC2979893 PMID: 21579901

Abstract

In the title compound, C₁₅H₁₀Cl₃NO₂, an intramolecular N—H⋯O hydrogen bond forms a six-membered ring and enforces an almost coplanar conformation for the acetamido group, the central benzene ring and the bridging carbonyl C—C(=O)—C group: the dihedral angles between the benzene ring and the acetamide and carbonyl C—C(=O)—C planes are 7.06 (11) and 7.17 (12)°, respectively. The dihedral angle between the two benzene rings is 67.43 (9)°. Because a strong hydrogen-bond donor is involved in the intramolecular interaction, the crystal packing is determined by weak C—H⋯O and C—H⋯Cl interactions.

Related literature

The title compound is isostructural with 2-chloroacetamido-5-chloro-2′-fluorobenzophenone (Prasanna & Guru Row, 2000 ▶). For the isostructurality index, see: Kálmán et al. (1991 ▶); Kubicki & Szafrański (1998 ▶). For a related structure, see: Malathy Sony et al. (2005 ▶). For the biological activity of benzophenone derivatives, see: Evans et al. (1987 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₁₅H₁₀Cl₃NO₂
M _r = 342.59
Triclinic,
a = 7.5776 (9) Å
b = 10.1565 (10) Å
c = 10.7862 (12) Å
α = 70.069 (8)°
β = 77.604 (9)°
γ = 70.388 (8)°
V = 730.47 (14) Å³
Z = 2
Cu Kα radiation
μ = 5.71 mm⁻¹
T = 295 K
0.35 × 0.2 × 0.2 mm

Data collection

Oxford Diffraction SuperNova (single source at offset) Atlas diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 ▶) T _min = 0.117, T _max = 0.319
5245 measured reflections
2917 independent reflections
2610 reflections with I > 2σ(I)
R _int = 0.017

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.113
S = 1.05
2917 reflections
230 parameters
All H-atom parameters refined
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.44 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Stereochemical Workstation Operation Manual (Siemens, 1989 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810003375/is2519sup1.cif

e-66-0o499-sup1.cif^{(17.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810003375/is2519Isup2.hkl

e-66-0o499-Isup2.hkl^{(140.2KB, 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
N8—H8⋯O1	0.84 (3)	1.95 (3)	2.634 (2)	138 (3)
C6—H6⋯Cl14ⁱ	0.94 (3)	2.87 (3)	3.675 (2)	143 (2)
C11—H11B⋯O10ⁱⁱ	0.93 (3)	2.50 (3)	3.320 (3)	147 (2)
C18—H18⋯Cl14ⁱⁱⁱ	0.95 (3)	2.84 (3)	3.745 (3)	161 (2)

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

Acknowledgments

BPS thanks R. L. FineChem, Bangalore, India, for the gift of a sample of the title compound.

supplementary crystallographic information

Comment

Benzophenone and related compounds have been reported to act as e.g., antiallergic, anti-inflammatory, antiasthmatic, antimalarial, anti-microbial and antianaphylactic agents (Evans et al., 1987). Here we report the crystal structure of 2-chloroacetamido-5-chloro-2'-chlorobenzophenone (alternative name: 2-chloro-N-{4-chloro-2-[(2-chlorophenyl)carbonyl]phenyl}acetamide; 1, Scheme 1), which is an intermediate in the synthesis of certain anxiolytic, anticonvulsant and sedative drugs, and is also a starting material for the synthesis of diazepam and other benzodiazepines.

The structure of 1 is isostructural with the previously described 2-chloroacetamido-5-chloro-2'-fluorobenzophenone derivative (Prasanna & Guru Row, 2000). Both compounds crystallize in the triclinic P-1 space group, and the unit cell dimensions are similar. Also the positions of the atoms in the unit cell are similar, after applying the transformation (index 1 refers to Prasanna & Guru Row, 2 - to the present structure): x₂=x₁+0.5, y₂=y₁+0.5, z₂=z₁+1.5. The isostructurality index (Kálmán et al., 1991), which describes the differences between the positions of the atoms in the unit cell has the value of 97.4% (for perfect isostructurality it should be 100%). Kubicki & Szafrański (1998) proposed the modification of this latter parameter which takes into account the point group symmetry and gives more absolute measure of the degree of isostructurality: it should be 1 for ideally isomorphous compounds and 0 for randomly distributed atoms. The value of this modified index is 0.94.

The conformation of 1 (Fig. 1) might be described by dihedral angles between four approximately planar fragments: acetamide [A, planar within 0.0065 (19) Å, with Cl2 atom significantly, by 0.110 (5)Å out of the plane], central phenyl [B, maximum deviation 0.0034 (14) Å], bridging carbonyl group C—C(=O)-C [C, max. deviation 0.015 (2) Å], and terminal phenyl [D, 0.0045 (19) Å]. The first three are close to coplanarity, the dihedral angles are A/B 7.06 (11)° and B/C 7.17 (12)°. Such a coplanar conformation of phenyl and carbonyl plane is quite uncommon for benzophenones, in a majority of the compounds found in the CSD (Allen, 2002) both phenyl rings are almost equally, and significantly, twisted with respect to the central plane. In the case of 1, as in some similar cases (for instance in the isostructural 2'-fluoro derivative but also in two crystal forms of 2-chloroacetamido-5-chlorobenzophenone (monoclinic: Prasanna & Guru Row, 2000, and triclinic: Malathy Sony et al., 2005), the factor responsible for such a coplanar conformation is the intramolecular hydrogen bond N—H···O (cf. Table 1). This hydrogen bond closes the six-membered ring, planar within 0.072 (7) Å. The second phenyl ring, which has no factor that can stabilize coplanar conformation, is typically, by 62.14 (10)°, twisted with respect to the bridge. The Cl atom of chloroacetamide group is anti with respect to the oxygen atom [O10—C9—C11—Cl12 torsion angle of 176.4 (2)°] and syn with respect to the N atom [N8—C9—C11—Cl12 is -4.8 (3)°]

In the crystal structure there are some weak C—H···O and C—H···Cl interactions, which might be of some importance when the strong hydrogen bond donor is involved in intramolecular interaction (Fig. 2)

Experimental

The title compound was obtained as a gift sample from R. L. FineChem, Bangalore, India. The compound was used without further purification. X-ray quality crystals were obtained by slow evaporation from ethyl acetate solution (m.p. 436-438 K).