Greener coumarin synthesis by Knoevenagel condensation using biodegradable choline chloride

Aqueous catalysis is an innovative task for the sustainable chemical industry. The use of biodegradable catalysts from natural sources may lead to greener reactions. Here, we report the synthesis of coumarin by Knoevenagel condensation using choline chloride as catalyst. Results show that even 10% of choline chloride can catalyze Knoevenagel condensation to yield coumarin in good yields. Almost all reactions proceeded faster, cleaner and in higher yields in aqueous media. Reaction mechanisms are proposed. The choline chloride catalyst was recycled five times without activity or yield decrease. Therefore, the synthesis of coumarin by Knoevenagel condensation using choline chloride as catalyst is a promising alternative to previously used procedures.