title: N-(3,4-Dimethyl-phen-yl)maleamic acid.
abstract: The title compound, C(12)H(13)NO(3), crystallizes with four independent mol-ecules in the asymmetric unit. The N-H bond and the C=O bond in the amide segment are anti to each other. The C=C double bond is cis configured and an intra-molecular O-H⋯O hydrogen bond is formed in each molecule. The mean planes through the aromatic ring and the amide group -NHCO- are inclined at angles of 17.4 (3), 20.8 (2), 16.2 (2) and 11.2 (3)° in the four mol-ecules. In the crystal, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into ribbons along the b axis.
authors.forename: B Thimme
authors.initials: BT
authors.lastname: Gowda
authors.forename: Miroslav
authors.initials: M
authors.lastname: Tokarčík
authors.forename: Jozef
authors.initials: J
authors.lastname: Kožíšek
authors.forename: K
authors.initials: K
authors.lastname: Shakuntala
authors.forename: Hartmut
authors.initials: H
authors.lastname: Fuess