7 Lipase-Catalyzed Peroxy Fatty Acid
Generation and Lipid Oxidation
Mark Ru ̈sch gen. Klaas and Siegfried Warwel
7.1 Introduction
Beside their industrial application for bleaching and as disinfectants, peroxy acids
are important oxidants in chemical industry as well as in organic laboratory synth-
esis. Examples for these oxidations are C¼C-epoxidation, Baeyer – Villiger-oxida-
tions, hydroxylation of aromatic rings and the oxidation of amines.
For all these reactions only a few peroxy acids, that are either easily generated in
situ (performic, peracetic and trifluoroperacetic acid), or that are reasonably stable
and can thus be stored (for example: mcpba,m-chloro perbenzoic acid; mmpp,
monoperoxy phthalic acid magnesium salt), are regularly applied.MCpbais still
the most often used peroxy acid in organic laboratory synthesis, although it is po-
tentially explosive (Heaney, 1993) and quite expensive. Peroxy fatty acids have
barely been used because until now no convenient synthetic route was known.
The standard method for the preparation of peroxy acids is the reaction of car-
boxylic acids with hydrogen peroxide catalyzed by a strong acid:
The larger the organic group R, the more stable is the resulting peroxy acid. On the
other hand, a larger group R also means that the reaction conditions for peroxy acid
generation (temperature, amount and acidity of the catalyst) have to be more severe.
Therefore, this synthetic method is not suitable for sensitive or long-chain substrates.
More elaborate procedures for the synthesis of particular peroxy acids (Folli et al.,
1968) are too expensive and tedious for a widespread use. In conclusion, there is an
urgent need for a new simple and versatile method for peroxy acid generation.
Such a new method was first developed by Bjo ̈rkling, Kirk and colleagues, a group
working at the Danish world-leading enzyme producer, Novo Nordisk A/S. They
found that even-numbered middle-chain C 6 –C 14 fatty acids can be converted
with hydrogen peroxide to the corresponding peroxy acids with yields of 33–
54 % (Bjo ̈rkling at al., 1990) when catalyzed by NovozymÒ435, an immobilized
lipase B fromCandida antarctica:
Enzymesin LipidModification.Editedby UweT. Bornscheuer
Copyright 2000 Wiley-VCHVerlagGmbH& Co. KGaA,Weinheim.ISBN:3-527-30176-3
