Solution growth and thermal treatment of crystals lead to two new forms of 2-((2,6-dimethylphenyl)amino)benzoic acid

N-(2,6-Di-chloro-phen-yl)-2-oxo-1,2-di-hydro-pyridine-3-carboxamide

Crystals of the title compound, C12H8Cl2N2O2, were obtained by slow evaporation of an ethano-lic solution. An intra-molecular amideN-H⋯O=Clactam hydrogen bond is observed. In the crystal, two mol-ecules pair up to form a centrosymmetric lactam-lactam dimers (LLD) by N-H⋯O=C hydrogen bonds, whereas the O=Camide group of the mol-ecule does not participate in hydrogen bonding.

Polymorphism and cocrystal salt formation of 2-((2,6-dichlorophenyl)amino)benzoic acid, harvest of a second form of 2-((2,6-dimethylphenyl)amino)benzoic acid, and isomorphism between the two systems

Isomorphism and isostructurality were observed between form I of 2-((2,6-dimethylphenyl)amino)benzoic acid and its analog 2-((2,6-dichlorophenyl)amino)benzoic acid, which suggests double Cl–CH3 exchange also leads to structural similarity.

Double substitution leads to a highly polymorphic system in 5-methyl-2-m-tolylamino-benzoic acid

Substitution on both aromatic rings of fenamic acid led to a highly polymorphic system in 5-methyl-2-m-tolylamino-benzoic acid, in contrast to the two mono-substituted analogs, which had only one or two forms obtained.

Conformational Flexibility and Substitution Pattern Lead to Polymorphism of 3-Methyl-2-(phenylamino)benzoic acid

To probe the effect of substitution on the benzoic acid ring on the polymorphism of phenylaminobenzoic acids, five 3-methyl-2-(phenylamino)benzoic acids (MPABAs) were synthesized. A preliminary polymorph screen led to one...

An investigation of the polymorphism of a potent nonsteroidal anti-inflammatory drug flunixin

Flunixin, a potent nonsteroidal anti-inflammatory drug widely used in veterinary medicine, was found to exist in at least two crystal forms, in contrast to clonixin which exists in four solvent-free forms and multiple solvates.

Orientation-dependent conformational polymorphs in two similar pyridine/pyrazine phenolic esters

The ring orientations in the conformational polymorphs of two similar pyridine/pyrazine phenolic esters were investigated to explore the effect of supramolecular assemblies in the solid state.

Comment on ‘Solution growth and thermal treatment of crystals lead to two new forms of 2-((2,6-dimethylphenyl)amino)benzoic acid’ by R. Hu, Y. Zhoujin, M. Liu, M. Zhang, S. Parkin, P. Zhou, J. Wang, F. Yu and S. Long, RSC Adv., 2018, , 15459

The two polymorphs reported by Long et al. are discussed point by point, suggesting that the newly reported crystal structure is in fact the same structure previously reported, differing in how the structure refinement was performed.