A solid solution of ethyl and -methyl 2-[(4-meth-yl-pyridin-2-yl)amino]-4-(pyridin-2-yl)thia-zole-5-carboxyl-ate.

The synthesis of ethyl 2-[(4-methyl-pyridin-2-yl)amino)-4-(pyridin-2-yl)thia-zole- 5-carboxyl-ate the Hantzsch reaction and partial transesterification during recrystallization from methanol- to the -methyl ester, resulting in the title solid solution, ethyl 2-[(4-methyl-pyridin-2-yl)amino)-4-(pyridin-2-yl)thia-zole-5-carboxyl-ate- -methyl 2-[(4-methyl-pyridin-2-yl)amino)-4-(pyridin-2-yl)thia-zole-5-carboxyl-ate (0.88/0.12), 0.88CHNOS·0.12CDHNOS, is reported. The refined ratio of ethyl to -methyl ester in the crystal is 0.880 (6):0.120 (6). The pyridine ring is significantly twisted out of the plane of the approximately planar picoline thia-zole ester moiety. N-H⋯N hydrogen bonds between the secondary amino group and the pyridine nitro-gen atom of an adjacent symmetry-related mol-ecule link the mol-ecules into polymeric hydrogen-bonded zigzag tapes extending by glide symmetry in the [001] direction. There is structural evidence for intra-molecular N⋯S chalcogen bonding and inter-molecular weak C-H⋯O hydrogen bonds between adjacent zigzag tapes.