1-acetyl-5-(4-methoxyphenyl)-3-(4-methoxy-styryl)-2-pyrazoline and 1-acetyl-5-(2-chlorophenyl)-3-(2-chlorostyryl)-2-pyrazoline

The structural details of two methoxy- and chloro-substituted pyrazoline derivatives (C21H22N2O3 and C19H16C12N2O, respectively) are presented. The two structures show considerable differences in the orientation of the phenyl ring attached to the heterocyclic ring, While the packing of the molecules in the methoxy-substituted derivative is characterized by a C-H ... O hydrogen bond, the packing in the chloro-substituted derivative is characterized by short Cl ... Cl contacts and C-H ... Cl intramolecular hydrogen bonds.