Metal particle size and swelling effect in the chiral hydrogenation of ethyl piruvate over Pt supported on resins

NICOLAS CARRARA; JUAN BADANO; GUSTAVO MENDOW; CARLOS VERA; MONICA QUIROGA

Florencia

Congreso; EuropaCat 2017; 2017

Sociedad Italiana de Química, Grupo de Catálisis

The increase of the size of the metal particles of Pt/resin catalysts was found to slighly improve the enantioselectivity in the reaction of selective hydrogenation of ethyl pyruvate (about 10% improvement). The Pt-Cinchonidine catalyst was able to achieve a 25% enantiomeric excess of (R)-ethyl lactate at the present reaction conditions. The reaction was found to be structure sensitive and the importance of the metal particle size for the adsorption of the chiral modiffier was proved. Sintering of the metal particles during nitrite reduction seemingly occurred with migration to the surface, producing some blocking of pore mouths and a decrease of the available surface area. There exists an optimal particle size that maximizes the enantiomeric excess, corresponding to a sintering time of 24 h. The adsorption of CD on a swollen resin seemed to improve the grafting of CD in the porous structure. Relatively good results of enantioslectivity were achieved during three reaction cycles.