Jump to main content
Jump to site search
Access to RSC content Close the message box

Continue to access RSC content when you are not at your institution. Follow our step-by-step guide.


Issue 17, 2018
Previous Article Next Article

A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids

Author affiliations

Abstract

Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-aliphatic, benzylic, hetero-aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.

Graphical abstract: A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids

Back to tab navigation

Supplementary files

Article information


Submitted
02 May 2018
Accepted
06 Jul 2018
First published
10 Jul 2018

Green Chem., 2018,20, 3931-3943
Article type
Paper

A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids

T. Knaus, V. Tseliou, L. D. Humphreys, N. S. Scrutton and F. G. Mutti, Green Chem., 2018, 20, 3931
DOI: 10.1039/C8GC01381K

Social activity

Search articles by author

Spotlight

Advertisements