Sonochemical enantioselective hydrogenation of ethyl pyruvate over platinum catalysts

• Published in: Ultrasonics sonochemistry 1997-10, Vol.4 (4), p.301-304
• Main Authors: Török, Béla, Felföldi, Károly, Szakonyi, Gerda, Bartók, Mihály
• Format: Article
• Language: English
• Subjects: Chemistry; Enantioselectivity; Exact sciences and technology; General and physical chemistry; Hydrogenation; Ketoester; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Platinum catalysts; Ultrasonic chemistry; Ultrasound
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/S1350-4177(97)00040-0

Chiral sonochemical hydrogenation of an aliphatic α-ketoester, ethyl pyruvate to ethyl lactate was carried out over various platinum catalysts in different solvents under atmospheric hydrogen pressure. The reaction rates and the enantiomeric excesses were determined over Pt/C, Pt/SiO 2 and Pt/K-10 catalysts both under conventional and sonochemical conditions. The effect of ultrasounds on the catalytic activity and enantioselectivity was tested applying sonochemical pretreatment before the reaction. The ultrasonic irradiation was found to be highly advantageous in these hydrogenations. After insonation of the catalysts, the enantioselectivity was highly improved over Pt/SiO 2 and Pt/K-10 catalysts. In addition, the reactions took place in quantitative yield and with complete chemoselectivity and the hydrogenation rates increased with one order of magnitude despite the very mild (atmospheric hydrogen pressure, room temperature) experimental conditions.