Ultrasound-assisted solvent-free synthesis of 3, 4-dihydropyrimidin-2(1H)-ones/thiones using polyindole as a recyclable catalyst

This paper describes the synthesis of polyindole by chemical oxidative polymerization using copper chloride as oxidant. Polyindole was characterized by various spectroscopic techniques like FT-IR, XRD, FESEM, and TGA. The XRD pattern confirms the semi-crystalline nature of polyindole. An efficient, solvent-free, ultrasound-assisted synthesis of biologically active 3,4-dihydropyrimidin-2(1 H)-one/thiones (DHPM) derivatives is reported by using polyindole as a recyclable catalyst. The advantages of this method are mild reaction conditions, short reaction time, excellent yields with high purity and low loading of catalyst. Polyindole can be used several times without loss of significant catalytic activity as compared to the other reported catalysts. Factors affecting on the rate of reaction, like use of ultrasonication, temperature, solvent, amount, and recyclability of catalyst have also been studied.

Automated summary

This paper describes the synthesis of polyindole using copper chloride as an oxidant and its characterization using various spectroscopic techniques. The polyindole was found to have a semi-crystalline nature through XRD analysis. A solvent-free, ultrasound-assisted synthesis of biologically active DHPM derivatives using polyindole as a recyclable catalyst was reported, showing advantages of mild reaction conditions, short reaction time, high yields, and low catalyst loading. Factors affecting the reaction rate, such as ultrasonication, temperature, solvent, catalyst amount, and recyclability, were also studied.