Tuesday, 19. October 2021 | 10:45 - 11:15

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«Application of flow chemistry in the fine chemical...»

Title:«Application of flow chemistry in the fine chemical industry – a photo-catalytical approach» Joël Wellauer, Dragan Miladinov, Thomas Buchholz, Jan Schütz, René T. Stemmler, Jonathan A Medlock, Werner Bonrath, Christof Sparr

Photo-chemical flow processes are applied at DSM Nutritional Products since many years. The sigmatropic isomerization of 7-dehydrocholesterol to previtamin D3 is carried out in a flow process under irradiation with ultraviolet light. In the production of calcifediol (25-OH-vitamin D3) a similar photo-chemical flow process is applied in the isomerization of 25-OH-7-dehydrocholestrol to 25-OH-previtamin D3 [1]. 
 
In several research and development projects at DSM Nutritional Products photo-chemical and photo-catalytical processes were studied. Important examples are the E/Z-isomerization of 3-methyl-pent-3-enynes, compounds used in the manufacture of vitamin A acetate and astaxanthin and the E/Z-isomerization of vitamin A acetate (the final product is (all-E)-vitamin A acetate) [2]. Another examples is the [2+2+2] cycloaddition of alkynes and nitriles to a precursor in the synthesis of vitamin B6 [3]. The oxidation of phenols and naphthols to their corresponding quinones was studied under photo-catalytic flow conditions [4]. Some of these quinones are intermediates in the manufacture of vitamin E and K3. The method allows to oxidize phenols with high selectivity under mild reaction conditions using visible light. The reactor design permits low photosensitizer loadings to generate singlet oxygen. This efficient phenol oxidation might become a valuable part in a sustainable approach to vitamin E and related compounds. 

Herein selected aspects of industrial applications of photo-catalytical flow processes will be discussed.
 

References:

[1]  I. Bendik, U. Höller, M. Marty, J. Schütz, L. Labler. Vitamins, 3. Vitamin D. In: Ullmann’s Encyclopedia of Industrial Chemistry, ed. Elvers. Online ed. Weinheim, Germany, Wiley-VCH Verlag GmbH & Co, 2019.
[2]  W. Bonrath, B. Ondruschka, WO2009080280, DSM, 02.07.2009.
[3]  W. Bonrath, B. Heller, WO2003027121, DSM, 03.04.2003.
[4]  J. Wellauer, D. Miladinov, T. Buchholz, J. Schütz, R. T. Stemmler, J. A. Medlock, W. Bonrath, C. Sparr, Chem. Eur. J. 2021, 27, 9748.

 

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