N-Isopropylbenzamide

In the title compound, C10H13NO, the dihedral angle between the amide group and the phenyl ring is 30.0 (3)°. In the crystal structure, intermolecular N—H⋯O hydrogen bonds link molecules into one-dimensional chains along the a axis.


Comment
The isopropylamine moiety is a common structural feature in many pharmaceutical compounds, in particular among β-adrenergic receptor antagonists (β-blockers) (Van Waarde et al., 2004;Kopka et al., 2005). Recent work in our laboratory Stephenson, van Oosten et al., 2008) and others (Van Waarde et al., 2004;Kopka et al., 2005) has focused on developing β-blockers labeled with the positron emitting isotope fluorine-18 (t 1/2 = 109.7 min) at the isopropyl moiety for medical imaging with positron emission tomography. It is established that substitution of fluorine into a drug often enhances its biological properties (Smart, 2001). Our goal is to structurally characterize the isopropylamine group for comparison with fluorinated analogs developed in our laboratory. Herein we report the single-crystal X-ray structure of the title compound, (I), (Fig. 1).
Experimental N-Isopropylbenzamide was made according to a literature procedure (Clayden et al., 2006), with minor modifications.
Benzoyl chloride (0.825 ml, 7.11 mmol) was added to CH 2 Cl 2 (17 ml, 0.4 M) under nitrogen. The mixture was cooled in an ice bath to 273 K and stirred for 10 min. Isopropylamine (1.8 ml, 21.33 mmol) was added dropwise. Upon completion of this addition the ice bath was removed and the reaction mixture was stirred at room temperature for 1.5 h. When the starting material was consumed (monitored by TLC) the reaction mixture was diluted with H 2 O (150 ml), extracted with CH 2 Cl 2 (3 × 50 ml), washed with H 2 O (2 × 100 ml) followed by brine (2 × 100 ml), dried over Na 2 SO 4 , and concentrated. No further purification was necessary. Colourless blocks of (I) were obtained by slow evaporation of a solution of the title compound

Refinement
In the absence of significant anamlous dispersion effects, Friedel pairs were merged before refinement. The H atoms bonded to C atoms were placed in calculated positions with C-H = 0.95 Å and 0.98 Å (methyl). They were included in the refinement in the riding-model approximation with U iso (H) = 1.2U eq (C) or U iso (H) = 1.5U eq (C) for methyl H atoms. The position of the H atom bonded to the N atom was refined independently with U iso (H) = 1.2U eq (N).
supplementary materials sup-2 Figures   Fig. 1. The molecular structure of (I) showing 30% probability displacement ellipsoids (arbitrary spheres for H atoms). Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.