Selective Oxidation in DSM Innovative Catalysts and Technologies

Paul L. ALSTERS, Jean-Marie AUBRY, Werner BONRATH, Corinne DAGUENET, Michael HANS, Walther JARY,  

Ulla LETINOIS, Veronique NARDELLO-RATAJ, Thomas NETSCHER, Rudy PARTON, Jan SCHUTZ, Jaap VAN SOOLINGEN, Johan UNGE and Bettina WUSTENBERG  

Selective oxidations are key transformations for the industrial production of a wide range of chemicals. Within DSM, oxidations reactions are used in the synthesis of vitamins and carotenoids, aroma compounds and polymer intermediates. Here we describe the use of both chemocatalysts and biocatalysts used in the industrial oxidation of aliphatic and aromatic systems, alcohols and poly hydroxyl-compounds. 

L-ascorbic acid or vitamin C (Fig. 16.1) is a water-soluble carbohydrate acid with antioxidant properties and is an essential nutrient for humans. It was first isolated from animal and plant sources in 1928. Five years later, the molecular structure of crystallised ascorbic acid was elucidated.  

The strong reducing behaviour of vitamin C is based on its enediol structure (Fig. 16.1). The oxidation of ascorbic acid is a two-step process in which semi-dehydroascorbic acid, a strong acid (dimmer form), is involved. This intermediate acts as a radical scavenger. The autoxidation of ascorbic acid is catalysed by transition metal ions and dehydroascorbic acid is formed in the presence of oxygen.  

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