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
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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.
KeywordsChiral and racemic hydrogenation Platinum Cinchonidine Ethyl pyruvate Methyl benzoylformate Pyruvic aldehyde dimethyl acetal 2,2-Diethoxyacetophenone Continuous-flow reactor
Financial support by the Hungarian National Science Foundation (OTKA Grant K 72065) is highly appreciated. The study was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences (Gy. Szőllősi).
- 2.Jannes G, Dubois V (eds) (1995) Chiral reactions in heterogeneous catalysis. Plenum Press, New YorkGoogle Scholar
- 3.De Vos DE, Vankelecom IFJ, Jacobs PA (eds) (2000) Chiral catalyst immobilization and recycling. Wiley-VCH, WeinheimGoogle Scholar
- 7.Ding K, Uozumi Y (eds) (2008) Handbook of asymmetric heterogeneous catalysis. Wiley-VCH, WeinheimGoogle Scholar
- 8.Hessel V, Schouten JC, Renken A, Wang Y, Yoshida J-I (eds) (2009) Handbook of micro reactors. Wiley-VCH, WeinheimGoogle Scholar
- 9.Luis SV, Garcia-Verdugo E (eds) (2010) Chemical reactions and processes under flow conditions. RSC Green Chemistry, LondonGoogle Scholar
- 24.Orito Y, Imai S, Niwa S (1979) J Chem Soc Jpn 670:1118Google Scholar
- 28.Červený L, Ružička V (1981) Adv Catal 30:30Google Scholar
- 41.Studer M, Burkhardt S, Blaser HU (1999) Chem Commun 1727Google Scholar