N-(4-Chloro-3-nitro­phen­yl)succinamic acid

In the title compound, C10H9ClN2O5, the nitro group is significantly twisted out of the plane of the benzene ring to which it is attached [dihedral angle = 27.4 (6)°]. In the crystal, mol­ecules are linked into centrosymmetric dimers via pairs of O—H⋯O hydrogen bonds. These dimers are further linked by N—H⋯O hydrogen bonds into double chains running along the a axis

4-Methyl-N-(4-methyl­phen­yl)benzamide

In the title compound, C15H15NO, the amide fragment has an anti conformation. The central amide group is tilted with respect to the benzoyl ring, forming a dihedral angle of 32.3 (5)°. The benzoyl and aniline rings make a dihedral angle of 59.6 (5)°. Mol­ecules are linked into infinite supra­molecular chains via N—H⋯O hydrogen bonds. The mol­ecule is disordered so that the aromatic rings are disposed across a twofold axis with equal occupancies

N-(4-Chloro-3-nitro­phen­yl)maleamic acid

In the mol­ecule of the title compound, C10H7ClN2O5, the acyclic C=C double bond is cis configured. The C=O and O—H bonds of the acid group are in a relatively rare anti position to each other, due to the donation of intramolecular hydrogen bond to the amide by the carboxyl group. The nitro group is significantly twisted [dihedral angle = 66.9 (3)°] out of the plane of the remaining atoms, which are almost coplanar (r.m.s. deviation for non-H atoms except the nitro group = 0.202 Å). In the crystal, N—H⋯O hydrogen bonds link the mol­ecules into zigzag chains running along the b axis

N-(2-Chloro-4-methyl­phen­yl)succinamic acid

In the title compound, C11H12ClNO3, the N—C=O fragment is twisted from the plane of the attached benzene ring by 48.39 (12)°. The carb­oxy­lic acid group is involved in O—H⋯O hydrogen bonding, which links pairs of mol­ecules into centrosymmetric dimers. N—H⋯O hydrogen bonds link these dimers, related by translation along the a axis, into ribbons

N-(4-Methyl-2-nitro­phen­yl)succinamic acid

In the title compound, C11H12N2O5, the conformation of the N—H bond in the amide segment is syn to the ortho-nitro group in the benzene ring. The amide C=O and the carboxyl C=O of the acid segment are syn to each other and both are anti to the H atoms on the adjacent –CH2 groups. Furthermore, the C=O and O—H bonds of the acid group are in syn positions with respect to each other. The dihedral angle between the benzene ring and the amide group is 36.1 (1)°. The amide H atom shows bifurcated intra­molecular hydrogen bonding with an O atom of the ortho-nitro group and an inter­molecular hydrogen bond with the carbonyl O atom of another mol­ecule. In the crystal, the N—H⋯O(C) hydrogen bonds generate a chain running along the [100] direction. Inversion dimers are formed via a pair of O—H⋯O(C) interactions, that form an eight-membered hydrogen-bonded ring involving the carboxyl group

N-(3-Chloro-2-methyl­phen­yl)succinamic acid

In the title compound, C11H12ClNO3, the dihedral angle between the benzene ring and the amide group is 44.9 (2)°. In the crystal, mol­ecules form inversion dimers via pairs of O—H⋯O hydrogen bonds. These dimers are further linked into sheets parallel to (013) via N—H⋯O hydrogen bonds

N-(3-Chloro-4-methyl­phen­yl)succinamic acid

In the crystal structure of the title compound, C11H12ClNO3, the asymmetric unit contains two independent mol­ecules. The N—H bond in the amide segment is anti to the meta-Cl atom in the benzene ring, in both molecules. The amide and carboxyl C=O bonds are also anti to each other and anti to the H atoms on the adjacent –CH2 groups. Furthermore, the C=O and O—H bonds of the acid group are in syn positions with respect to each other. The dihedral angles between the benzene ring and the amide group are 40.6 (2) and 44.9 (3)° in the two independent molecules. In the crystal, mol­ecules are packed into sheets parallel to the (11-3) plane through O—H⋯O and N—H⋯O hydrogen bonds

A note on the Scombroid fish Scomber japonicus observed along the Indian Coast

On 24. 2. 1999 a fish specimen closely resembling mackerel was observed along with the landings of mackerel [Rastrelliger Kanagurta) by a purse seiner at Tadri fishing harbour. The fish was later identified as Scomber Japonicus. Popularly called the chub mackerel