1,2-Diphenyl-2-(m-tolyl­amino)ethanone

Rafael Mendoza Meroño; Felix Nápoles Esculary; Laura Menéndez Taboada; Santiago García-Granda

doi:10.1107/S1600536810013371

. 2010 Apr 17;66(Pt 5):o1107. doi: 10.1107/S1600536810013371

1,2-Diphenyl-2-(m-tolylamino)ethanone¹

Rafael Mendoza Meroño ^a, Felix Nápoles Esculary ^b, Laura Menéndez Taboada ^a, Santiago García-Granda ^a,^*

PMCID: PMC2979094 PMID: 21579159

Abstract

The title compound, C₂₁H₁₉NO, belongs to the family of α-aminoketones. The structure contains three benzene rings, two of which [the phenyl ring in the 1-position (B) and the methylaniline ring (A)] are nearly coplanar [dihedral angle = 5.4 (1)°], whereas the phenyl ring in the 2-position (C) is nearly normal to them [dihedral angles = 81.8 (1) and 87.0 (1)° for A/C and B/C, respectively]. The conformation of the N—H bond is syn to the C=O bond, favouring the formation of a centrosymmetric dimer of molecules in the crystal structure. The molecular packing is consolidated by this N—H⋯O hydrogen-bonding network.

Related literature

For the structure of alpha-aminoketones, see: Batsanov et al. (2006 ▶). For the crystal structure of 1,2-diphenyl-2-(p-tolylamino)ethanone, see: Au & Tafeenko (1986 ▶).

Experimental

Crystal data

C₂₁H₁₉NO
M _r = 301.37
Triclinic,
a = 6.0510 (3) Å
b = 11.5745 (4) Å
c = 12.9458 (7) Å
α = 112.542 (5)°
β = 97.396 (4)°
γ = 99.960 (4)°
V = 805.62 (8) Å³
Z = 2
Cu Kα radiation
μ = 0.59 mm⁻¹
T = 293 K
0.34 × 0.12 × 0.07 mm

Data collection

Oxford Diffraction Xcalibur Gemini S diffractometer
Absorption correction: refined from ΔF [cubic fit to sin(theta)/lambda - 24 parameters; Parkin et al. (1995 ▶)] T _min = 0.919, T _max = 0.960
8027 measured reflections
2833 independent reflections
2174 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.137
S = 1.09
2833 reflections
213 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2008 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2008 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810013371/su2170sup1.cif

e-66-o1107-sup1.cif^{(20.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810013371/su2170Isup2.hkl

e-66-o1107-Isup2.hkl^{(139KB, hkl)}

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

Enhanced figure: interactive version of Fig. 1

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H22⋯O1ⁱ	0.859 (17)	2.660 (17)	3.3913 (17)	143.8 (15)

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Symmetry code: (i) Inline graphic .

Acknowledgments

Financial support by the Agencia Española de Cooperación Internacional y Desarrollo (AECID), FEDER funding, the Spanish MICINN (MAT2006–01997 and Factoría de Cristalización Consolider Ingenio 2010) and the Gobierno del Principado de Asturias (PCTI) is acknowledged. Special acknowledgements go to Professor José Manuel Concellón for his support and scientific advice.

supplementary crystallographic information

Comment

The structure of various members of the alpha-aminoketone family have been extensively studied (Batsanov et al., 2006). These compounds can be used as intermediates to synthesize other biologically active compounds like thiosemicarbazones. Alpha-aminoketones also exhibit biological activity but are less active than the thiosemicarbazones. They are generally synthesised by the reaction of an alpha-hydroxiketone with an amine.

The molecular structure of the title molecule is illustrated in Fig. 1. According to the dihedral angles between the benzene rings planes, two benzene rings are nearly coplanar whereas the central ring is almost normal to them (5.3 (1)° for A/B, 81.8 (1)° for A/C and 87.0 (1)° for B/C). Comparing these values with those in the similar structure where the methyl subtitutent is in the para position (5.1° for A/B, 86.28° for A/C and 84.19° for B/C), there are no noticeable differences (Au & Tafeenko, 1986).

In the crystal structure, the molecular packing is made up of a network of weak hydrogen-bonding interactions (Fig. 2 & Table 1), favouring the formation of centrosymmetric dimers. Such conformations bring the C═O and N—H bonds into a syn orientation. The intermolecular distance between the centroids of the parallel benzene rings is ca. 3.77 Å. This value suggests the absence of any relevant π-stacking interactions.

Experimental

0.0235 mol benzoin, 0.0235 mol 3-methylaniline and 0.0235 mol boric acid were added to 10 ml of ethyleneglycol. The mixture was heated to reflux for 1 h, then 15 ml of ethanol were added and the mixture cooled to RT. The reaction was followed using TLC. The yellow precipitate obtained was washed with cold water and ethanol (yield 85%). Yellow needle-like crystals, suitable for x-ray diffraction analysis, were obtained after a week by slow evaporation of a solution in ethanol.