Related Experiment Video
Updated: Oct 19, 2025
A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis
Published on: February 16, 2020
Heterogeneous Isomerization for Stereoselective Alkyne Hydrogenation to trans-Alkene Mediated by Frustrated Hydrogen
Weijie Zhang1, Ruixuan Qin1, Gang Fu1
1State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, National & Local Joint Engineering Research Center for Preparation Technology of Nanomaterials and National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Abstract:
Stereoselective production of alkenes from the alkyne hydrogenation plays a crucial role in the chemical industry. However, for heterogeneous metal catalysts, the olefins in cis-configuration are usually dominant in the products due to the most important and common Horiuti-Polanyi mechanism involved over the metal surface. In this work, through combined theoretical and experimental investigations, we demonstrate a novel isomerization mechanism mediated by the frustrated hydrogen atoms via the H2 dissociation at the defect on solid surface, which can lead to the switch in selectivity from the cis-configuration to trans-configuration without overhydrogenation. The defective Rh2S3 with exposing facet of (110) exhibits outstanding performance as a heterogeneous metal catalyst for stereoselective production of trans-olefins. With the frustrated hydrogen atoms at spatially separated high-valence Rh sites, the isolated hydrogen mediated cis-to-trans isomerization of olefins can be effectively conducted and the overhydrogenation can be completely inhibited. Furthermore, the bifunctional Rh-S/Pd nanosheets have been synthesized through the surface modification of Pd nanosheets with rhodium and sulfide. With the selective semihydrogenation of alkynes into cis-olefins catalyzed by the small surface PdS ensembles, the bifunctional Rh-S/Pd nanosheets exhibit excellent activity and stereoselectivity in the one-pot alkyne hydrogenation into trans-olefin, which surpasses the most reported homogeneous and heterogeneous catalysts.
More Related Videos
12:08Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes
Published on: June 24, 2022
08:25Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks MOFs
Published on: January 17, 2020
Related Concept Videos
02:13Reduction of Alkenes: Catalytic Hydrogenation
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
02:36Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.