Veredelung nachwachsender Rohstoffe durch Selektivoxidation mit Goldkatalysatoren

Abstract

Die Gold‐katalysierte Selektivoxidation von Aldehyden und Alkoholen zu den korrespondierenden Carbonsäuren kann für die Funktionalisierung verschiedener Substanzen auf Basis nachwachsender Rohstoffe, z. B. Kohlenhydrate oder Fettalkoholethoxylate, in Zukunft große Bedeutung erlangen. Bei der Kohlenhydratoxidation weisen Goldkatalysatoren eine sehr hohe Aktivität sowie eine exzellente Selektivität und Langzeitstabilität auf und erlauben somit eine hocheffiziente Herstellung verschiedenster Aldonsäuren. Auch bei der Selektivoxidation von Ethoxylaten zeigen Goldkatalysatoren, dass diese universell, mit guter Aktivität und sehr guter Selektivität zu den entsprechenden Ethercarbonsäuren umgesetzt können.

Kinetics of l-arabinoseoxidation over supported goldcatalysts with in situcatalyst electrical potential measurements

“…Aqueous phase selective oxidation of sugars is generally carried out in a weakly acidic or alkaline medium. 19 Since the reaction results in the drop of pH due to the acid product formation, the pH of the reaction media was regulated and kept constant during the course of the experiment by an automatic pH controller. The influence of pH is complex as it can affect the reaction in several ways.…”

Carbohydrate structure–activity relations of Au-catalysed base-free oxidations: gold displaying a platinum lustre

“…Surprisingly, Au behaves completely different compared to Pt under these alkaline conditions: e.g. Glc oxidation is much faster compared to Gal 16,17 (Equatorial HO-4 preferred over axial orientation for Au, contrary to Pt). Rautiainen et al 18 included variation at C6 (CH 2 OH and CO 2 À ), by adding the uronic acid analogues GlcA and GalA, but did not nd a large inuence of C6-position on the reaction rate (Glc > Gal z GlcA z GalA), while De Wit et al 15 clearly found this inuence for Pt-catalysts (Gal > Glc > GalA > GlcA).…”

From batch to continuous: Au-catalysed oxidation of d-galacturonic acid in a packed bed plug flow reactor under alkaline conditions

“…At high catalyst loadings and reaction rates, batch oxidations can become limited in oxygen supply, as was previously reported for glucose oxidations. 23,29,30 It was therefore decided to investigate if this was also the case for the Na-GalA oxidation in batch.…”