Novel continuous catalytic hydrogenation process for the synthesis of diacetone-d-allose

Abstract Diacetone- d -allose is an important building block for the synthesis of pharmaceutical ingredients. The current batch production process involves a chemical oxidation and a reduction step that include hazardous reagents, produce a large amount of waste and require an extensive downstream processing. Current investigations aim to develop a catalytic reduction process of the intermediate diacetone- d -ketoglucose (DAKG) with molecular hydrogen, a green solvent, and a heterogeneous metal catalyst. Improvement of productivity and simultaneous reduction of the environmental impact shall be achieved by transforming the conventional batch procedure into a continuous process with a stationary catalyst packing. The screening studies presented in this work revealed that high reaction rates and a high selectivity (>98%) can be achieved with a commercial platinum catalyst under mild conditions in an aqueous buffer solution. Transition from batch into a continuous process was realized in several mini-scale fixed bed reactors to provide a fast screening and high mass transfer rates. A high selectivity (99%) and a conversion of 30% was achieved. The results indicate that the reactor performance was influenced by internal diffusion limitations and also by external mass transfer. To attain full conversion of DAKG, the reaction was performed in a random packed bed reactor and a selectivity of >96% was achieved.