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2026
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| Online Access: | https://doi.org/10.5281/zenodo.19044494 |
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| author | R. Padma*, D. Manohar Raghava, E. Rupa Sai Lakshmi Prasana, G. Sarada, M. Jhansi Lakshmi |
| author_facet | R. Padma*, D. Manohar Raghava, E. Rupa Sai Lakshmi Prasana, G. Sarada, M. Jhansi Lakshmi |
| contents | <p><span>Pyrazolines are an important class of five-membered nitrogen-containing heterocycles<span> </span>that have<span> </span>attracted<span> </span>considerable<span> </span>attention<span> </span>due<span> </span>to<span> </span>their<span> </span>wide<span> </span>range<span> </span>of biological and pharmacological activities. In the present work, a convenient and efficient method for the synthesis of substituted pyrazolines from chalcones has been investigated. Chalcones, serving as versatile α,β-unsaturated carbonyl intermediates, were first prepared via Claisen–Schmidt condensation between appropriately substituted aromatic aldehydes and acetophenones under basic conditions. The synthesized chalcones were then subjected to cyclization reactions with<span> </span>hydrazine hydrate and<span> </span>substituted phenyl hydrazines to<span> </span>afford the corresponding pyrazoline derivatives. The reactions were carried out under<span> </span>mild reflux conditions using ethanol as a solvent, providing good to excellent yields within<span> </span>short<span> </span>reaction<span> </span>times.<span> </span>The<span> </span>progress<span> </span>of<span> </span>the<span> </span>reactions<span> </span>was<span> </span>monitored<span> </span>by<span> </span>thin- layer chromatography, and the products were isolated by simple filtration and recrystallization techniques. The structures of the synthesized pyrazolines were confirmed by spectroscopic methods such as FT-IR, ^1H NMR, and mass spectrometry. Pyrazolines Show Antimicrobial Activity Against Both <strong>Gram- positive<span> </span>bacteria<span> </span></strong>such<span> </span>as<span> </span><em>staphylococcus<span> </span>aureus<span> </span></em>and<span> </span><em>bacillus<span> </span>subtilis</em>,<span> </span>and<span> </span><strong>gram- negative<span> </span>bacteria<span> </span></strong>including<span> </span><em>escherichia<span> </span>coli<span> </span></em>and<span> </span><em>pseudomonas<span> </span>aeruginosa</em>.<span> </span>their antifungal activity has been demonstrated against organisms like <em>candida albicans </em>and <em>aspergillus </em>species. structure–activity relationship studies indicate that the antimicrobial activity of pyrazolines is influenced by the nature and position of substituents on the pyrazoline ring. <strong>electron-withdrawing groups </strong>(such as chloro, bromo, nitro, and fluoro) on aromatic rings generally enhance antimicrobial potency. increased <strong>lipophilicity </strong>improves penetration through microbial cell membranes, while substitutions at the nitrogen atoms of the pyrazoline ring may improve binding with microbial enzymes.</span></p> |
| format | Recurso digital |
| id | zenodo_https___doi_org_10_5281_zenodo_19044494 |
| institution | Zenodo |
| language | eng |
| publishDate | 2026 |
| publisher | Zenodo |
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| spellingShingle | SYNTHESIS OF PYRAZOLINES FROM CHALCONES R. Padma*, D. Manohar Raghava, E. Rupa Sai Lakshmi Prasana, G. Sarada, M. Jhansi Lakshmi <p><span>Pyrazolines are an important class of five-membered nitrogen-containing heterocycles<span> </span>that have<span> </span>attracted<span> </span>considerable<span> </span>attention<span> </span>due<span> </span>to<span> </span>their<span> </span>wide<span> </span>range<span> </span>of biological and pharmacological activities. In the present work, a convenient and efficient method for the synthesis of substituted pyrazolines from chalcones has been investigated. Chalcones, serving as versatile α,β-unsaturated carbonyl intermediates, were first prepared via Claisen–Schmidt condensation between appropriately substituted aromatic aldehydes and acetophenones under basic conditions. The synthesized chalcones were then subjected to cyclization reactions with<span> </span>hydrazine hydrate and<span> </span>substituted phenyl hydrazines to<span> </span>afford the corresponding pyrazoline derivatives. The reactions were carried out under<span> </span>mild reflux conditions using ethanol as a solvent, providing good to excellent yields within<span> </span>short<span> </span>reaction<span> </span>times.<span> </span>The<span> </span>progress<span> </span>of<span> </span>the<span> </span>reactions<span> </span>was<span> </span>monitored<span> </span>by<span> </span>thin- layer chromatography, and the products were isolated by simple filtration and recrystallization techniques. The structures of the synthesized pyrazolines were confirmed by spectroscopic methods such as FT-IR, ^1H NMR, and mass spectrometry. Pyrazolines Show Antimicrobial Activity Against Both <strong>Gram- positive<span> </span>bacteria<span> </span></strong>such<span> </span>as<span> </span><em>staphylococcus<span> </span>aureus<span> </span></em>and<span> </span><em>bacillus<span> </span>subtilis</em>,<span> </span>and<span> </span><strong>gram- negative<span> </span>bacteria<span> </span></strong>including<span> </span><em>escherichia<span> </span>coli<span> </span></em>and<span> </span><em>pseudomonas<span> </span>aeruginosa</em>.<span> </span>their antifungal activity has been demonstrated against organisms like <em>candida albicans </em>and <em>aspergillus </em>species. structure–activity relationship studies indicate that the antimicrobial activity of pyrazolines is influenced by the nature and position of substituents on the pyrazoline ring. <strong>electron-withdrawing groups </strong>(such as chloro, bromo, nitro, and fluoro) on aromatic rings generally enhance antimicrobial potency. increased <strong>lipophilicity </strong>improves penetration through microbial cell membranes, while substitutions at the nitrogen atoms of the pyrazoline ring may improve binding with microbial enzymes.</span></p> |
| title | SYNTHESIS OF PYRAZOLINES FROM CHALCONES |
| url | https://doi.org/10.5281/zenodo.19044494 |