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oa Synthesis of some substituted pyrazole-1-carbothioamides and spectral correlations in 3-(3,4-dibromophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamides
- Source: QScience Connect, Volume 2013, Issue 1, يونيو ٢٠١٣,
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- ٣٠ أبريل ٢٠١٣
- ٠٣ يونيو ٢٠١٣
- ٠١ يوليو ٢٠١٣
ملخص
Background: This study aims to synthesise a series of 1-thiocarbomyl pyrazolines, including 3-(3,4-dibromophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamides, using solvent-free fly-ash:PTS catalyzed cyclization between chalcones and thiosemicarbazide, under microwave irradiation. Then to characterize them using analytical, physical and spectroscopic data.
Methods: Solvent-free microwave assisted cyclization was adopted for the synthesis of 1-thiocarbomyl, including 3-(3,4-dibromophenyl)-5-(substituted phenyl)-4,5-dihydro-1H- pyrazole-1-carbothioamides, using fly-ash:PTS as the catalyst. They were characterised by IR, NMR and mass spectroscopic data. The infrared (IR) and nuclear magnetic resonance (NMR) spectral data was correlated with substituent constants, F and R parameters, using Hammett equation, to study the effect of substituents.
Results: The yields of the synthesised chalcones were more than 85%. The spectral data of these 3-(3,4-dibromophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamides had been correlated, using single and multi-linear regression analysis. These gave a satisfactory or fair degree of correlation with some parameters.
Conclusion: Easy handling, non-hazardous and environmentally benign cyclization method had been adopted for the synthesis of 1-thiocarbomyl pyrazolines using fly-ash:PTS as catalyst, with better yields. Some of the Hammett spectral correlations were found to be satisfactory, with the observed spectroscopic data.