ZIOC Researchers First Described Zelinsky Reaction Mechanism

In 1924, great Russian chemist Nikolay D. Zelinsky found out that charcoal was able to efficiently catalyze benzene production by acetylene trimerization. This process, even almost a hundred years later, is a major transformation in organic synthesis and industry that allows obtaining an aromatic ring from linear hydrocarbons. Anyhow, its mechanism has remained a mystery until recently.

The ZIOC researchers, under the guidance of Prof. V.P. Ananikov, succeeded to describe for the first time the Zelinsky reaction mechanism using quantum chemistry. The key to the understanding of the reaction appeared to be carbene active sites localized on carbon atoms at the zigzag edge of graphene. They represent an ideal platform for the effective formation of carbon-carbon bonds in the synthesis of benzene from acetylene. It was found that continuous oscillation of the spin density promotes stepwise addition of acetylene molecules to the catalytic site and a larger difference in free energies supports the dominance of cyclotrimerization over linear oligomerization of acetylene. Also, the experiments showed that acetylene could trimerize to benzene on the carbon material formed during the reaction. It proves that catalytically active sites can be present in a wide variety of carbon materials.

The studies are an important stage in the evolution of the carbocatalysis theory – the use of carbon as a catalyst for chemical reactions. In the future, it will be able to replace heavy metals that are currently conventional for many transformations due to its much lower cost and low toxicity.

Source:

E. G. Gordeev, E. O. Pentsak, V. P. Ananikov, Carbocatalytic Acetylene Cyclotrimerization: A Key Role of Unpaired Electron Delocalization, J. Am. Chem. Soc., 2020, 142, 3784-3796. DOI:10.1021/jacs.9b10887