A Remarkably Simple Aza-Michael Reaction with Citrus Fruit Juice

Introduction: Citrus fruit juice is used in the Aza-Michael reaction of secondary amines with carbonyl compounds. Clearly, citrus fruit juice acts as a solvent and an acidic catalyst. More-over, the reaction proceeds well at room temperature and produces the products in high yields. The Aza-Michael addition is a widely used carbon–nitrogen bond-forming reaction in organic syn-thesis, traditionally requiring catalysts, organic solvents, or elevated temperatures. With increasing focus on green chemistry, there is a demand for sustainable reaction conditions that are both effec-tive and environmentally benign. This study explores a novel approach using common citrus fruit juice as a natural, eco-friendly medium for promoting the Aza-Michael reaction. Methods: Fresh citrus juices (lemon, lime, and orange) were extracted and used without modifica-tion. A series of amines were reacted with α,β-unsaturated carbonyl compounds in the juice medium at room temperature. Reactions were monitored by thin-layer chromatography (TLC). Products were isolated via standard extraction and characterized using NMR. Results: Efficient Aza-Michael addition reactions were achieved using citrus juices, especially lemon juice, due to its high citric acid content and low pH. The reactions proceeded at room tem-perature, without any added catalyst or organic solvent. A variety of amines and Michael acceptors yielded the corresponding adducts in good to excellent yields. The method displayed good func-tional group tolerance and reproducibility. Discussion: The Michael reaction of secondary amines with unsaturated ketones and esters in citrus juice yields high products. Lime juice reacts faster due to its high acidity, allowing for easy opera-tion, environmentally friendly reaction conditions, green chemistry, fast reactions, and high product yields. Conclusion: This study introduces an innovative and practical green chemistry approach to a classic organic reaction. The use of citrus juice as a natural reaction medium offers a safe, cost-effective, and biodegradable alternative to conventional synthetic protocols.