Synthesis and Fungitoxicity of some Substituted Δ²-Pyrazolines

Nineteen substituted Δ²-pyrazolines were synthesised in the laboratory and characterised by physico-chemical techniques. These compounds were evaluated for their fungicidal activity against Rhizoctonia bataticola and Sclerotium rolfsii. The compounds showed mild fungitoxicity against the test fungi. 1-H-3-phenyl-5-(4-N,N-dimethylarninophenyl)-2-pyrazoiine (ED₅₀ 232 ppm) and 1-H-3-(2-phenyl vinyl)-5-phenyl-2-pyrazoline (ED₅₀ 237 ppm) look promising against R. bataticola when compared with quintozene (ED₅₀41 ppm), the reference fungicide. Amongst all the test chemicals, 1-acetyl-3-ethoxy-5-methyl-2-pyrazoline (ED₅₀ 248 ppm) was found to be most active against S. Rolfsii. All N-acetylated derivatives exhibited better fungitoxicity than their precursors.