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Z. Naturforsch. 2012,
67b, 995 – 1004
doi:10.5560/ZNB.2012-0176
The Boundary Layer as Reaction Compartment for the Synthesis of Hydroxyalkyl-functionalized Siloxanes
Institute of Chemical Technology, Freiberg University of Mining and Technology, 09596 Freiberg (Sa.), Germany
Reprint requests to Professor M. Bertau. Fax: +49 3731 39-2324. Tel.: +49 3731 39-2384. E-mail:
martin.bertau@chemie.tu-freiberg.de
Received June 28, 2012 / published online October 8, 2012
Dedicated to Professor Heribert Offermanns on the occasion of his 75th birthday
Enzyme catalysis in two-phase systems, particularly in the functionalization of siloxanes, is a new challenge for biocatalysis. On the basis of three different reaction systems, stirred tank reactor, enzyme membrane reactor and micro mixer, the influence of the phase boundary layer along the interface between an aqueous system and an organosiloxane on the synthesis of hydroxyalkyl-functionalized siloxanes is discussed and solutions presented. Micro mixers produce, through a large surface area to volume ratio, boundary layers within which through a formate dehydrogenase-catalyzed reaction the conversion of 1,3-bis-(3-formoxypropyl)tetramethyldisiloxane to 1,3-bis-(3-hydroxypropyl)tetramethyldisiloxane can be achieved. In contrast, in a stirred tank reactor even after 96 h only 45 % of the formoxy siloxane has been converted.
Key words: Enzymes, Siloxanes, Protection Group