Catalysis Letters

, 141:1616

The First Case of Competitive Heterogeneously Catalyzed Hydrogenation using Continuous-Flow Fixed-Bed Reactor System: Hydrogenation of Binary Mixtures of Activated Ketones on Pt-Alumina and on Pt-Alumina-Cinchonidine Catalysts

Article

DOI: 10.1007/s10562-011-0705-0

Cite this article as:
Szőllősi, G., Makra, Z., Fülöp, F. et al. Catal Lett (2011) 141: 1616. doi:10.1007/s10562-011-0705-0

Abstract

Under the experimental conditions of the Orito reaction the competitive hydrogenations of four binary mixtures of ethyl pyruvate (EP), methyl benzoylformate (MBF), pyruvic aldehyde dimethyl acetal (PA) and 2,2-diethoxyacetophenone (DAP) on unmodified Pt/Al2O3 (racemic hydrogenation) and catalyst modified by cinchonidine (chiral hydrogenation) were studied using continuous-flow fixed-bed reactor system (CFBR). Conversions of chiral and racemic hydrogenations were determined under 4 MPa H2 pressure, at 293 K using toluene/acetic acid 9/1 as solvent. In the competitive chiral hydrogenation of MBF + EP and DAP + PA binary mixtures (S1 + S2) a new phenomenon was observed: namely the EP and PA are hydrogenated faster than MBF and DAP, whereas in racemic one the MBF and DAP are hydrogenated faster than the former ketones. The phenomenon verified for the first time in CFBR is dependent on the adsorption mode of the surface complexes of various compositions (S1–Pt, S2–Pt, S1–CD–Pt, S2–CD–Pt, CD = cinchonidine). In the chiral hydrogenation of DAP a rate decrease, i.e., “ligand deceleration” was observed instead of rate enhancement.

Graphical Abstract

https://static-content.springer.com/image/art%3A10.1007%2Fs10562-011-0705-0/MediaObjects/10562_2011_705_Figa_HTML.gif

Keywords

Chiral and racemic hydrogenationPlatinumCinchonidineEthyl pyruvateMethyl benzoylformatePyruvic aldehyde dimethyl acetal2,2-DiethoxyacetophenoneContinuous-flow reactor

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.Stereochemistry Research Group of the Hungarian Academy of SciencesSzegedHungary
  2. 2.Department of Organic ChemistryUniversity of SzegedSzegedHungary
  3. 3.Institute of Pharmaceutical ChemistryUniversity of SzegedSzegedHungary