Green Chemistry Blog

The asymmetric, enzymatic reduction of ketones has been enhanced with a graphene derived light harvesting photocatalyst. Typically the use of reducing enzymes for specialty chemical synthesis is restricted by the cost of the redox cofactor. In this example the enzyme cofactor is recycled via a rhodium complex. The energy needed to do this is delivered by the chlorophyll mimicking graphene. Enantioselectivity to the resulting alcohols is high, and applicable to both aliphatic and aromatic ketones.

The scientists from KRICT responsible for this research believe that artificial photosynthesis using functionalised graphene shows promise for energy generation and sustainable chemical production in the near future, with applications including carbon dioxide sequestering reactions already proven as viable.

Check out the full article – online now!

Virginia Nykänen and colleagues at Aalto University, Finland have transformed rice starch into a temporally stable, optically transparent, biodegradable plastic with a high degree of mechanical strength and good thermal resistance.

This important step towards bioplastics made from simple and sustainable resources has potential applications in food packaging and biomedical materials.

Read the full article here in Chemistry World.

This paper is free to access until 8 September, so download it now:

V P S Nykänen et al, Green Chemistry, 2014, DOI: 10.1039/c4gc00794h

Fermentation strategies for the production of bio-fuels will continue to grow in importance, and as they do, problems with retrieving the products from dilute fermentation broths and the low energy content of short-chain alcohols will be magnified. A partnership between the energy company Shell and the Qingdao Institute of Bioenergy and Bioprocess Technology is addressing this challenge by using catalysis to condense bio-ethanol or bio-butanol via the Guerbet reaction to give improved, higher-alcohol biofuels.

An immobilised iridium catalyst was successful in converting 1-butanol in aqueous solution to 2-ethyl-1-hexanol with >85% selectivity over five consecutive reactions. The upgrading of ethanol was less selective to a single product: In addition to 1-butanol, 2-ethyl-1-butanol and even traces of 1-octanol were observed. A phenanthroline ligand is required to facilitate the aqueous phase reaction, conditions that mimic the environment of a fermentation broth. This approach also negates the usual requirement of hydrogen gas to reduce the β-unsaturated aldehyde intermediate, with the reaction proceeding under air.

These results all indicate that this reaction shows great potential for producing biofuels, as well as many other useful chemicals, in a cheaper and more efficient way.

Check out the full article – online now!