N-(2,3-Dimethylphenyl)-2,2,2-trimethylacetamide

The N—H bond in the title compound, C13H19NO, is anti to the C=O bond and is also anti to both the 2- and 3-methyl substituents in the aromatic ring. In the crystal, intermolecular N—H⋯O hydrogen bonds link the molecules into chains propagating along the c axis.

The N-H bond in the title compound, C 13 H 19 NO, is anti to the C O bond and is also anti to both the 2-and 3-methyl substituents in the aromatic ring. In the crystal, intermolecular N-HÁ Á ÁO hydrogen bonds link the molecules into chains propagating along the c axis.

Comment
As part of a study of the effect of ring and side chain substitutions on the crystal structures of chemically and biologically important class of compounds such as aromatic amides (Gowda et al., 2007a, b, c), the crystal structure of 2,2,2-trimethyl-N-(2,3-dimethylphenyl)-acetamide has been determined.
In the title compound, the molecules are linked into chains (Fig. 2) running along the c axis by intermolecular N-H···O hydrogen bonds (Table 1).

Experimental
The title compound was prepared according to the literature method (Shilpa & Gowda, 2007). The purity of the compound was checked by determining its melting point. It was characterized by recording its infrared and NMR spectra (Shilpa & Gowda, 2007). Single crystals of the title compound were grown by slow evaporation of its ethanolic solution at room temperature.

Refinement
The tert-butyl group is disordered over three orientations with occupancies of 0.743 (14), 0.153 (7) and 0.104 (13). All C-C/C···C distances involving disordered atoms were restrained to be equal and also they were subjected to a rigid bond restraint. The U ij components of the disordered atoms were restrained to approximate isotropic behaviour. The N-bound H atom was located in a difference map and was allowed to ride on the N atom. The remaining H atoms were positioned geometrically and refined using a riding model [C-H = 0.93-0.96 Å]. The U iso parameter for all H atoms were set to 1.2 times of the U eq of the parent atom.

Special details
Geometry. All e.s. 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.