Synthesis and Biological Activity of Some New Pyrazolin-5-one and Pyrazole Derivatives.

N'–(2–hydroxybenzoyl)–3–methyl–4–(substituted arylhydrazono)pyrazolin–5–ones, N–(2– hydroxybenzoyl)–3,5–dimethyl–4–(substituted arylazo)pyrazoles, N–(p–toluenesulphonyl)–3–methyl–4– (substituted arylhydrazono)pyrazolin–5–ones, and N–(p–toluenesulphonyl)–3,5–dimethyl–4–(substituted arylazo)pyrazoles have been synthesized in good yields and characterized by IR, NMR and elemental analyses. The compounds were evaluated for their in vitro antibacterial activity against some Gram-positive bacteria, Staphylococcus aureus and Gram-negative bacteria, Escherichia Coli. The compounds showed moderate to good antibacterial activities.