Selective Hydrogenation of L-proline to L-prolinol over Al2O3-supported Pt-MoOx Catalyst

L-proline, one of abundant amino acids, can be utilized as a biobased feedstock for the synthesis of an amino alcohol, L-prolinol, which serves as chiral auxiliary in a variety of asymmetric synthesis. Herein we examined selective hydrogenation of L-proline into L-prolinol over M MoOx/Al2O3 (M=Pt, Rh, Pd, and Ru) in aqueous H3PO4 solution. Pt-MoOx/Al2O3 exhibited high activity among the catalysts, affording L-prolinol in 75% selectivity and >99.9% enantiomeric excess, while Pt/Al2O3 was inactive. Mo species were highly dispersed as a polyoxo cluster on both Pt nanoparticles and Al2O3 support, and participated concertedly with Pt nanoparticles in the hydrogenation. Activated carboxyl group of L-proline by MoOx species on Pt nanoparticle are readily hydrogenated with dissociative hydrogen formed on the same Pt nanoparticle with MoO, species, giving an effective route for the hydrogenation of L-proline. Pt-MoOx/Al(2)O(3 )could be identified as an active and reusable catalyst due to no loss of its original activity.

Automated summary

The selective hydrogenation of L-proline into L-prolinol using M MoOx/Al2O3 catalysts was investigated in this study. Pt-MoOx/Al2O3 catalyst exhibited higher activity and selectivity in the reaction. The Mo species, highly dispersed on both Pt nanoparticles and Al2O3 support, participated in the hydrogenation process.