An Efficient Synthesis Of α, β Unsaturated Ketones Via Claisen–Schmidt Condensation Reaction Using Amino Acid Based Ionic Liquids

Abstract

Synthesis of chalcone by Claisen–Schmidt condensation using recyclable L- aspartic acid coupled imidazolium-based ionic liquid as a green synthetic approach has been developed. Present work offers significant advantages such as high yield, enhanced reaction speed even at room temperature, catalyst reusability, and the involvement of non-toxic reagents. Chalcones are a flavonoid family and have pharmacological and biological activities. It includes antibacterial, antifungal, immunosuppressive, and anti-nociceptive properties. Ionic liquid has emerged as a powerful tool for molecular organic solvents and wide liquid range, ease of recovery and reuse, and making them a greener alternative to volatile organic solvents. Thus, our objective was to employ them as dual catalyst and solvent systems to synthesize chalcone via CS condensation in the present work. In a typical experiment, benzaldehyde (10 mmol), acetophenone (10 mmol), and 2.5 mol% (L-AAIL) ionic liquid were mixed in a 50 mL round-bottom flask. The reaction was preceded quickly at room temperature with stirring, the resulting mixture became a biphasic system with the residue at the bottom and the upper phase containing some unreacted substrate separated from the catalyst by filtration and decantation. The catalyst was extracted with CH2Cl2 and split for the next cycle. Claisen–Schmidt condensation accomplished with reasonable to good yields, ranged from 78 to 95% at room temperature in the presence of the [L-AAIL], as compared to the traditional route at more than 100O C. [L-AAIL] are found a highly efficient and eco-friendly catalyst for synthesizing chalcone derivatives at room temperature. [L-AAIL] as a solvent and catalyst will exhibit real advantages by providing a ‘green’ process with the safer operation, Short reaction periods, mild reaction conditions, easier separation, and reusability of ionic liquid made this methodology valuable for synthetic organic chemists as well as industry.