Iowa State University researchers have developed a new synthetic route for coumalic acid from malic acid. This new method eliminates the use of fuming sulfuric acid as a reagent, and instead uses dichloroethane as a solvent for the malic acid and a weak acid as the reagent. These much more moderate reaction conditions should make scale up for production of coumalic acid much more feasible. In addition, other products such as fumaric acid may also be synthesized by adjusting the reaction conditions.

http://www.google.com/patents/WO2014189926A1?cl=en

http://patents.com/us-20160122311.html

http://www.orgsyn.org/demo.aspx?prep=CV4P0201

Dear Anurag Chaudhary,

Please, find in attach a paper on: the preparation of COUMALIC ACID

Organic Syntheses, Coll. Vol. 4, p.201 (1963); Vol. 31, p.23 (1951).

Taking in your consideration the following notes:

Notes

1. A technical free-flowing powder, melting at 126–128°, was used.

2. This washing is essential to remove the mineral acid and to avoid partial esterification that otherwise takes place during the methanol recrystallization step.

3. The submitters state that an additional 10–12 g. of crude acid can be obtained from the filtrate by extraction with ether in a continuous extractor.

4. Depending on the color of the crude acid, several additional recrystallizations may be required to obtain a colorless product.

Best wishes