Cobalt(II)-catalyzed direct acetylation of alcohols with acetic acid
Subbarayan Velusamy, Sarbani Borpuzari and T. Punniyamurthy
*Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati
781 039, India, Email: tpunni
iitg.ernet.in
S. Velusamy, S. Borpuzari, T. Punniyamurthy, Tetrahedron, 2005, 61, 2011-2015.
DOI: 10.1016/j.tet.2005.01.006
Abstract
Cobalt(II) chloride hexahydrate efficiently catalyzes the acetylation of alcohols with AcOH in high yields without the need to remove water. This protocol is also effective with other carboxylic acids. The catalyst can be recycled.
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Details
The study explores the use of cobalt(II) chloride hexahydrate (CoCl2·6H2O) as an efficient and recyclable catalyst for the direct acetylation of alcohols with acetic acid (AcOH). This method offers high yields and is also effective with other carboxylic acids like trifluoroacetic acid, propanoic acid, phenylacetic acid, and benzoic acid, producing acylated products in moderate to good yields. The process does not require the removal of water, making it environmentally friendly and cost-effective. The catalyst can be filtered and reused without losing its activity. The study demonstrates that aromatic, allylic, and saturated alcohols can be converted to their corresponding acetates under mild conditions. Primary alcohols show higher reactivity compared to secondary alcohols, and polyols undergo complete acetylation. The method avoids the use of strong mineral acids, which pose environmental hazards, and offers an economical alternative to traditional esterification methods. The reaction mechanism is suggested to proceed via a Lewis acid catalyzed process. The catalyst's recyclability was confirmed through multiple cycles without significant loss of efficiency. This protocol provides a practical and sustainable approach for the esterification of alcohols in organic synthesis.
Key Words
Esterification, Acetylation, Alcohol, Carboxylic acid, Cobalt(II) chloride, Catalyst
ID: J72-Y2005-2840
