title: Ultrasonically improved semi-hydrogenation of alkynes to (Z-)alkenes over novel lead-free Pd/Boehmite catalysts.
abstract: This paper reports the application of ultrasound in the semi-hydrogenation of alkynes over two novel Pd/Boehmite catalysts. The semi-hydrogenations of phenylacetylene, diphenylacetylene and 2-butyne-1,4-diol have either been investigated in an ultrasonic bath under atmospheric hydrogen pressure, or in an ultrasonic horn reactor under 0.1-0.5MPa hydrogen pressure. Alkyne hydrogenation was suppressed by sonication under atmospheric hydrogen pressure, but promoted by sonication under 0.1MPa of hydrogen pressure. Sonication increased selectivity towards the semi-hydrogenated products in both cases. Catalyst loading, hydrogen pressure, temperature and the presence of quinoline, all impacted on hydrogenation rate, activity and selectivity to semi-hydrogenated products. Palladium leaching from the catalyst was evaluated in ethanol and hexane both under plain stirring and sonication.
authors.affiliation: Dipartimento di Scienza e Tecnología del Farmaco and NIS - Centre for Nanostructured Interfaces and Surfaces, Universty of Turin, Via P. Giuria 9, I-10125 Turin, Italy.
authors.forename: Zhilin
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Dipartimento di Scienza e Tecnología del Farmaco and NIS - Centre for Nanostructured Interfaces and Surfaces, Universty of Turin, Via P. Giuria 9, I-10125 Turin, Italy. Electronic address: giancarlo.cravotto@unito.it.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Cravotto
authors.affiliation: Dipartimento di Scienza e Tecnología del Farmaco and NIS - Centre for Nanostructured Interfaces and Surfaces, Universty of Turin, Via P. Giuria 9, I-10125 Turin, Italy.
authors.forename: Emanuela Calcio
authors.initials: EC
authors.lastname: Gaudino
authors.affiliation: Dipartimento di Scienza e Tecnología del Farmaco and NIS - Centre for Nanostructured Interfaces and Surfaces, Universty of Turin, Via P. Giuria 9, I-10125 Turin, Italy.
authors.forename: Agnese
authors.initials: A
authors.lastname: Giacomino
authors.affiliation: DSM Nutritional Products Ltd., Research and Development, P.O. Box 2676, 4002 Basel, Switzerland.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Medlock
authors.affiliation: DSM Nutritional Products Ltd., Research and Development, P.O. Box 2676, 4002 Basel, Switzerland.
authors.forename: Werner
authors.initials: W
authors.lastname: Bonrath
keywords: Alkynes; Catalyst activity; Catalyst selectivity; Semi-hydrogenation; Ultrasound