Mechanistic study on dimerization of acetylene with a Nieuwland catalyst

A mechanistic study on the Nieuwland catalysis for dimerization of acetylene is performed by detecting copper-acetylene and copper- monovinylacetylene π-complexes and also by examining the kinetics under virtually the same reaction conditions employed in the industrial process. An efficient H/D exchange occurs between acetylene and protons in the Nieuwland catalytic system. Addition of a coordinating ligand to the conventional Nieuwland catalytic system results in improvement of the catalytic activity and selectivity for the acetylene dimerization. The kinetic analysis including the kinetic deuterium isotope effect provides valuable insight into the Nieuwland catalytic mechanism of the dimerization of acetylene.