Efficient acetylation of primary amines and amino acids in environmentally benign brine solution using acetyl chloride
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Acetyl chloride is one of the most commonly available and cheap acylating agent but its high reactivity and concomitant instability in water precludes its use to carry out acetylation in aqueous medium. The present methodology illustrates the efficient acetylation of primary amines and amino acids in brine solution by means of acetyl chloride under weakly basic condition in the presence of sodium acetate and/or triethyl amine followed by trituration with aqueous saturated bicarbonate solution. This effort represents the first efficient use of this most reactive but cheap acetylating agent to acetylate amines in excellent yields in aqueous medium. This is a potentially useful green chemical transformation where reaction takes place in environment-friendly brine solution leading to easy work-up and isolation of the amide derivatives. Mechanistic rationale of this methodology is also important.
KeywordsAmines acetyl chloride brine sodium acetate triethyl amine
We thank Prof. Krishnangshu Roy, Director and Prof. Santanu Tripathi, Head of the Department of Clinical and Experimental Pharmacology, School of Tropical Medicine, Kolkata for their interest in the work. We also thank Dr. Gautam Chattopadhyay, Post-Graduate Department of Chemistry, Presidency College for insightful discussions. We thank the Council of Scientific and Industrial Research (CSIR), New Delhi, India for providing a Senior Research Fellowship (Grant No. 09/951(0001)/2008-EMR-I) to one of the authors (SC).
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