7.3.4 Oxidation of fatty aldehydes
Autooxidation of aldehydes to carboxylic acid esters by molecular oxygen proceeds
via peroxy acids. Therefore, fatty aldehydes can be oxidized quantitatively to fatty
acids (or directly to fatty acid esters) with high selectivity by NovozymÒ435 and
H 2 O 2 (Figure 8). Again, two methods can be used; the oxidant can be generated from
a free carboxylic acid, or from a carboxylic acid ester. In contrast to epoxidation, the
first method is extremely convenient for aldehyde oxidation. By addition of a cat-
alytic amount of the desired carboxylic acid to the aldehyde the reaction can be
started, and because of the growing amount of acid in the reaction mixture becomes
autocatalytic. When the reaction is complete, there is only a single organic substance
in the product. The second method does not yield the carboxylic acid but, in a two-
step – one-pot reaction, the carboxylic acid ester, because the intermediate acid is
esterified by the excess of ethyl acetate.
7.4 References
Bjo ̈rkling, F., Godtfredsen, S.E., Kirk, O. (1990), Lipase-mediated formation of peroxy carboxylic acids
used in catalytic epoxidation of alkenes,J. Chem. Soc.,Chem. Commun.1301–1303.
Bjo ̈rkling, F., Frykman, S.E., Godtfredsen, S.E., Kirk, O. (1992), Lipase-catalyzed synthesis of peroxy
carboxylic acids and lipase mediated oxidations,Tetrahedron4587–4592.
Corey, E.J., Niva, H., Falk, J.R. (1979), Selective epoxidation of eicosa-cis-5,8,11,14–tetraenoic arachi-
donic acid and eicosa-cis-8,11,14-trienoic acid,J. Am. Chem. Soc. 101 , 1586–1587.
Folli, U., Iarossi, D., Montanari, F., Torre, G. (1968), Asymmetric induction and configurational correla-
tions in oxidation at sulphur. Part III. Oxidations of aryl alkyl sulphides to sulphoxides by optically
active peroxy-acids,J. Chem. Soc. (C)1317–1322.
Frykman, H.B., Isbell, T.A. (1997), Synthesis of 6-hydroxyd-lactones and 5,6-dihydroxy eicosanoic/
docosanoic acids from meadowfoam fatty acidsviaa lipase-mediated self-epoxidationJ. Am. Oil
Chem. Soc. 74 , 719–722.
126 7 Lipase-Catalyzed Peroxy Fatty Acid Generation and Lipid Oxidation
Figure 8. Two methods for chemo-enzymatic aldehyde oxidation.