Simple, sustainable and inexpensive method developed for converting alcohols to carboxylic acids using table salt

Carboxylic acids are needed as bulk chemicals in diverse fields including pharmaceutical drugs, fine chemicals and polymers. More than 450 drug molecules have carboxylic acid units present in them. Dicarboxylic acids such as terephthalic acid are precursors for many commonly used polymers such as polyethylene terephthalate (PET) which is used in the manufacture of mineral water bottles and Kevlar, a polymer five times stronger than steel used for making bullet proof vests. The global production of aryl carboxylic acids is estimated to exceed 620 kilotons by 2023.

Researchers at the Department of Chemistry, IIT Delhi have now developed a simple, environmentally friendly and economical method for converting organic alcohols to carboxylic acids using the kitchen chemical, sodium chloride (table salt) as catalyst in water medium along with a base and a green oxidant. This is also the first report where the ubiquitous sodium chloride is shown to act as a catalyst.

The work was carried out by Susanta Hazra (Ph.D student) along with Ajay Kishor Kushawaha (M.Tech student) and Deepak Yadav (M.Sc student) under the guidance of Prof. Anil J. Elias. The team showed that one can carry out this simple reaction even in an open vessel and also by using filtered sea water as solvent and catalyst.

The methodology does not require rigorous purification methods such as chromatography which would have involved use of organic solvents. The team extended this study for the oxidation of amines to imines as well. The oxidation was carried out successfully on 40 different substrates.

The work has recently appeared as a communication in the journal ‘Green Chemistry’ [Green Chem. (RSC); 2019, Advance article; DOI: 10.1039/C9GC00497A].