Related Experiment Video
Updated: May 18, 2026

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions
Published on: October 5, 2019
Visible-Light Driven Acetylene Semi-Hydrogenation to Ethylene With a Copper Photosensitizer and a Cobaloxime Catalyst
Anna Fortunato1, Sharon Silloni1, Brando Adranno1
1Department of Chemical Sciences, Università di Padova, Padova, Italy.
Abstract:
The purification of ethylene streams from acetylene impurities remains a key industrial challenge, for which light-powered strategies are emerging as sustainable alternatives to conventional approaches. Recent studies have shown that hydrogen atom transfer (HAT) pathways enable highly selective acetylene semi-hydrogenation by ensuring rapid and controlled hydrogen delivery while suppressing over-hydrogenation or H2 evolution. Here, we report a fully noble-metal-free homogenous photocatalytic system in which a molecular cobaloxime catalyst [Co(dmgH)2(Im)Cl] (dmg = dimethylglyoxime, Im = imidazole) operates in tandem with a Cu-based photosensitizer [Cu(N^N)(P^P)]+ to drive the selective transfer hydrogenation from acetylene to ethylene under visible light irradiation. Under a pure C2H2 atmosphere, our system converts acetylene to ethylene with a turnover number (TON) of 670 after 48 h of visible-light irradiation with 99.6% selectivity, while under ethylene-rich conditions, acetylene impurities are completely removed with 99.3% selectivity. Mechanistic studies reveal that catalysis proceeds via a CoIII─H intermediate. Overall, this work demonstrates that rational pairing of cobaloxime catalysts with earth-abundant Cu-based photosensitizers provides an efficient and sustainable strategy for photocatalytic acetylene semi-hydrogenation and ethylene purification.
Related Concept Videos
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Reduction 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.
Reduction 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 surface of...
Reduction 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...
![[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
