Green Synthesis of Coumarin-Chalcone Hybrid (3-Cinnamoyl-2H-chromen-2-one) Using Stirring Method

Abstract

Hybridisation between the two pharmacophores, namely coumarin and chalcone, opens opportunities to increase their activity as anti-bacterial. This study uses the green synthesis method, which applies the neat reaction principle. The precursor that was synthesised first, namely 3-acetylcoumarin through the Knoevenagel Condensation reaction by reacting 2-hydroxybenzaldehyde and ethyl acetoacetate with diethylamine catalyst using the microwave irradiation method for 2 minutes. The purity of the reaction is monitored through TLC and melting point tests. The resulting product is a pale yellow solid with a yield of 46% and a melting point of 124-126°C. Then, it synthesises 3-cinnamoyl-2H-chromen-2-one through the Claisen-Schmidt Condensation reaction by reacting 3-acetylcumarin and benzaldehyde using a concentrated HCl catalyst. The reaction was stirred and then left at room temperature for 18 hours. Then, it was washed in cold aquadest before recrystallisation. The purity of the reaction is monitored through TLC and melting point tests. The resulting product is a pale-yellow solid with a yield of 19.1% and a melting point of 168-171°C.