PdPb-Catalyzed Decarboxylation of Proline to Pyrrolidine: Highly Selective Formation of a Biobased Amine in Water

• Published in: ACS catalysis Vol. 6; no. 11; pp. 7303 - 7310
• Main Authors: Verduyckt, Jasper, Van Hoof, Maarten, De Schouwer, Free, Wolberg, Marike, Kurttepeli, Mert, Eloy, Pierre, Gaigneaux, Eric M, Bals, Sara, Kirschhock, Christine E. A, De Vos, Dirk E
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04.11.2016
• Subjects: PdPb; decarboxylation; biobased amine; l-proline; water; pyrrolidine
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.6b02561

Amino acids have huge potential as platform chemicals in the biobased industry. Pd-catalyzed decarboxy­lation is a very promising route for the valorization of these natural compounds derived from protein waste or fermentation. We report that the highly abundant and nonessential amino acid l-proline is very reactive in the Pd-catalyzed decarboxy­lation. Full conversions are obtained with Pd/C and different Pd/MeO x catalysts; this allowed the identification of the different side reactions and the mapping of the reaction network. Due to the high reactivity of pyrrolidine, the selectivity for pyrrolidine was initially low. By carefully modifying Pd/ZrO2 with Pb in a controlled mannervia two incipient wetness impregnation stepsthe selectivity increased remarkably. Finally, a thorough investigation of the reaction parameters resulted in an increased activity of this modified catalyst and an even further enhanced selectivity under a low H2 pressure of 4 bar at 235 °C in water. This results in a very selective and sustainable production route for the highly interesting pyrrolidine.