Gold nanocatalysed oxidation of free carbohydrates

Catalytic transformation of biomass-derived natural resources into valuable compounds is of great interest for sustainable development. Particularly, sugar acids obtained by selective oxidation of carbohydrates are very valuable molecules in many areas such as detergency, medicine (pharmaceuticals), and cosmetics. The choice of a robust and highly selective catalyst for oxidation of the aldehyde function vs. hydroxy groups is crucial for such transformations of polyhydroxy aldehyde compounds. In this respect, gold nanoparticles have been shown to be highly chemoselective, favouring high yields of the desired glyconic acid. Nevertheless, several key parameters from catalyst design to reaction conditions should be considered to perform highly efficient catalytic transformation. This chapter aims at highlighting the influence of catalyst material properties such as nature of the support, gold nanoparticle size or synthetic method, on the one hand, and of reaction parameters (pH, temperature, nature of the oxidant, ratio between carbohydrate and gold etc.) on the other hand. Particular emphasis is also placed on the versatility of the reaction (application to other mono- and oligosaccharides) and on the use of alternative methods for activating these heterogeneous catalysts.