Substituted 4-Acyl-5-methyl-2-phenyl-pyrazol-3-one-phenylhydrazones with antioxidant properties: X-ray crystal and spectroscopic studies

Phenylhydrazine was reacted with synthesized acylpyrazolone derivatives 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one and 4-propyl-5-methyl-2-phenyl-pyrazol-3-one,to obtain two new azomethine phenylhydrazones,a study in continuation of our probe into the effects of acyl group substitutions on the physicochemical and free radical scavenging properties of acylpyrazolone schiff bases. the keto imine tautomers of 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one-phenylhydrazone (empp-ph) and 4-propyl-5-methyl-2-phenyl-pyrazol-3-one-phenylhydrazone (prmpp-ph) according to single x-ray crystallography data which precipitated in good yield are reported. furthermore they have been characterized by elemental analysis,ftir,13c and 1h nmr,and mass-spectroscopy techniques. both phenylhydrazone schiff bases crystallize in a triclinic crystal system,each with a space group of p-1 (number 2) having short intramolecular n3 - h3.o1 hydrogen interaction between the first hydrazine hydrogen h3 and the pyrazolone oxygen o1. the antioxidant free radical scavenging activities of titled compounds against 2,2-diphenyl-1-picrylhydrazyl (dpph) showed a positive response almost as good as that of vitamin c under the same conditions,with the propyl substituted 4-propyl-5-methyl-2-phenyl-pyrazol-3-one-phenylhydrazone (prmpp-ph) having a stronger activity (calculated ic50 value of 175.66 μg/ml). © 2017 omoruyi g. idemudia et al.