Synthesis and Spectroscopic Characterization of Some New Biological Active Azo–Pyrazoline Derivatives

A number of 3‐[4‐(benzyloxy)‐3‐(2‐Chlorophenylazo)‐phenyl]‐5‐(substituted‐phenyl)‐1‐substituted‐2‐pyrazolines( 4a‐j) and (5a‐j) have been synthesized by diazotization of 2‐chloroaniline and its coupling reaction with 4‐hydroxy acetophenone, followed by benzyloxation of the hydroxyl group to give the substrate [4‐benzyloxy‐3‐(2‐chlorophenylazo)‐acetophenone (1)].The prepared starting material (1) has been reacted with different substituted benzaldehydes to give a new series of chalcone derivatives 1‐[(4‐benzyloxy)‐3‐(2‐chloro‐phenylazo)‐phenyl]‐3‐(substituted phenyl)‐2‐propen‐1‐one (3a‐j), in high yields and in a few minutes, and the later compounds were treated with hydrazine hydrate according to Michael addition reaction to afford a new biolological active target compounds (4a‐j) and (5a‐j). Furthermore, The structures of the newly synthesized compounds were confirmed by FT‐IR, 13 C‐NMR, 13 C‐DEPT & 1 H‐NMR spectral data. The chalcone and pyrazoline derivatives were evaluated for their anti bacterial activity against Escherichia coli as gram negative and Staphylococcus aureus as gram positive, the results showed significant activity against both types of bacteria.