Green recipe for organic acid salts
doi:10.1038/nindia.2013.1 Published online 8 January 2013
Researchers have devised a new, safer and cleaner process for synthesising carboxylic acids and carboxylic acid salts1. This process uses water as the oxygen source and will be very useful at both laboratory and industrial scales for producing various chemicals.
The oxidation of alcohols to carboxylic acids is an important industrial reaction used in the synthesis of bulk and fine chemicals. Traditionally, this transformation takes place in the presence of harmful chlorinated solvents and oxidant molecules with catalytic ruthenium and chromium oxides, resulting in copious waste.
This could be averted if water were used to convert alcohols to carboxylic acid salts. However, no studies have tested the potential of water in such chemical conversions. In the hope of finding safer processes to produce acid salts from alcohols, the researchers carried out reactions mixing water and primary alcohols with ruthenium complexes as catalyst in an atmosphere of argon gas connected to a bubbler. This led to production of carboxylic acids.
Addition of sodium hydroxide converted carboxylic acids to their carboxylic acid salts and reformed the catalyst. The carboxylic acid salts could be converted to carboxylic acids by acid treatment. These experiments do not yield intermediates such as esters in acid synthesis and highlight an important role of the base in scavenging the formed acid and allows the catalyst to reform.
The transformation of primary alcohols to carboxylic acid salts happens at low catalyst loadings in basic aqueous solution with simultaneous generation of hydrogen gas.
The authors of this work are from: Department of Organic Chemistry, Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel and SRM Research Institute, SRM University, Kattankulathur, Tamil Nadu, India.
- Balaraman, E. et al. Catalytic transformation of alcohols to carboxylic acid salts and H2 using water as the oxygen atom source. Nat. Chem. doi: 10.1038/nchem.1536 (2013)