N-(2,3-Dimethylphenyl)succinamic acid

In the title compound, C12H15NO3, the conformations of N—H and C=O bonds in the amide segment are anti to each other and that of the amide H atom is syn to the ortho- and meta-methyl groups in the benzene ring. In the crystal, the molecules are linked into infinite chains through intermolecular O—H⋯O and N—H⋯O hydrogen bonds.

In the title compound, C 12 H 15 NO 3 , the conformations of N-H and C O bonds in the amide segment are anti to each other and that of the amide H atom is syn to the ortho-and meta-methyl groups in the benzene ring. In the crystal, the molecules are linked into infinite chains through intermolecular O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds.

Comment
In the present work, as a part of studying the effect of ring and side chain substitutions on the crystal structures of anilides (Gowda et al., 2010a,b,c), the crystal structure of N-(2,3-dimethylphenyl)-succinamic acid (I) has been determined. The conformations of N-H and C═O bonds in the amide segment are anti to each other (Fig. 1). The conformation of the amide oxygen and the carbonyl oxygen of the acid segment are almost midway between the syn and anti conformations, in contrast to the anti conformation observed in N-(2-methylphenyl)succinamic acid (II) (Gowda et al., 2010c) and the syn conformation observed in N-(3-methylphenyl)succinamic acid (III) (Gowda et al., 2010a). Further, the conformation of the amide C═O bond is anti to the H atoms of its adjacent -CH 2 groups ( Fig. 1) and that of the carbonyl oxygen of the acid segment is almost midway between the syn and anti conformations. The C═O and O-H bonds of the acid group are in syn position to each other, similar to that observed in (II) and (III).
The conformation of the amide hydrogen is syn to the ortho-and meta-methyl groups in the benzene ring, similar to that observed between the amide hydrogen and the ortho-methyl group in (II), but contrary to the anti conformation observed between the amide hydrogen and the meta-methyl group in the benzene ring of (III).
The intermolecular O-H···O and N-H···O hydrogen bonds pack the molecules into infinite chains in the structure (Table 1, Fig.2).
The modes of interlinking carboxylic acids by hydrogen bonds is described elsewhere (Leiserowitz, 1976). The packing of molecules involving dimeric hydrogen bonded association of each carboxyl group with a centrosymmetrically related neighbor has also been observed (Jagannathan et al., 1994).

Experimental
The solution of succinic anhydride (0.01 mole) in toluene (25 ml) was treated dropwise with the solution of 2,3-dimethylaniline (0.01 mole) also in toluene (20 ml) with constant stirring. The resulting mixture was stirred for about one h and set aside for an additional hour at room temperature for completion of the reaction. The mixture was then treated with dilute hydrochloric acid to remove the unreacted 2,3-dimethylaniline. The resultant solid N-(2,3-dimethylphenyl)-succinamic acid was filtered under suction and washed thoroughly with water to remove the unreacted succinic anhydride and succinic acid.
It was recrystallized to constant melting point from ethanol. The purity of the compound was checked by elemental analysis and characterized by its infrared and NMR spectra.
The prism like colorless single crystals used in X-ray diffraction studies were grown in ethanolic solution by slow evaporation at room temperature.    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.