N-(2-Methylphenyl)maleamic acid

Abstract

In the title compound, C11H11NO3, the conformation of the N—H bond is anti to the C=O bond in the amide segment, while it is syn to the ortho-methyl group in the phenyl ring. In the maleamic acid unit, the amide C=O bond is anti to the adjacent C—H bond, while the carboxyl C=O bond is syn to the adjacent C—H bond. The C=O and O—H bonds of the acid group are in the relatively rare anti position to each other. This is an obvious consequence of the intramolecular O—H...O hydrogen bond donated to the amide carbonyl group. The ortho-substituted phenyl ring makes a dihedral angle of 12.7 (1)° with the mean plane of the maleamic acid unit. In the crystal structure, intermolecular N—H...O hydrogen bonds link the molecules into zigzag chains parallel to [001]. These chains are further linked into sheet by weak π–π interactions [centroid–centroid distance = 3.425 (2) Å].