Breakage of the C-N bond is a structure sensitive process,and the catalyst size significantly affects its activity.On the active metal nanoparticle scale,the role of catalyst size in C-N bond cleavage has not been cle...Breakage of the C-N bond is a structure sensitive process,and the catalyst size significantly affects its activity.On the active metal nanoparticle scale,the role of catalyst size in C-N bond cleavage has not been clearly elucidated.So,Ru catalysts with variable nanoparticle sizes were obtained by modulating the reduction temperature,and the catalytic activity was evaluated using 1,2,3,4-tetrahydroquinoline and o-propylaniline with different C-N bond hybridization patterns as reactants.Results showed a 13 times higher reaction rate for sp3-hybridized C-N bond cleavage than sp2-hybridized C-N bond cleavage,while the reaction rate tended to increase first and then decrease as the catalyst nanoparticle size increased.Different concentrations of terrace,step,and corner sites were found in different sizes of Ru nanoparticles.The relationship between catalytic site variation and C-N bond cleavage activity was further investigated by calculating the turnover frequency values for each site.This analysis indicates that the variation of different sites on the catalyst is the intrinsic factor of the size dependence of C-N bond cleavage activity,and the step atoms are the active sites for the C-N bond cleavage.When Ru nanoparticles are smaller than 1.9 nm,they have a strong adsorption effect on the reactants,which will affect the catalytic performance of the Ru catalyst.Furthermore,these findings were also confirmed on other metallic Pd/Pt catalysts.The role of step sites in C-N bond cleavage was proposed using the density function theory calculations.The reactants have stronger adsorption energies on the step atoms,and step atoms have d-band center nearer to the Fermi level.In this case,the interaction with the reactant is stronger,which is beneficial for activating the C-N bond of the reactant.展开更多
An efficient Pd/Cu-catalyzed oxidative self-carbonylation of arylhydrazine with CO and molecular oxygen as an oxidant to afford symmetrical biaryl ketones via C—N bond activation has been developed.In this approach,a...An efficient Pd/Cu-catalyzed oxidative self-carbonylation of arylhydrazine with CO and molecular oxygen as an oxidant to afford symmetrical biaryl ketones via C—N bond activation has been developed.In this approach,arylhydrazine hydrochlorides are used as a green arylating agent which releases nitrogen and water as byproducts.This developed protocol significantly restricts the formation of aryl iodide and homo-coupled azobenzene products even under favorable conditions.A library of symmetrical biaryl ketones with wide functionalities was synthesized in good yields under mild conditions.展开更多
基金supported by the Key Project of National Natural Science Foundation of China(Grant No.22038008)the Science and Technology Innovation Project of National Energy Group China Shenhua Coal to Oil Chemical Co.(Grant No.MZYHG-2021-01).
文摘Breakage of the C-N bond is a structure sensitive process,and the catalyst size significantly affects its activity.On the active metal nanoparticle scale,the role of catalyst size in C-N bond cleavage has not been clearly elucidated.So,Ru catalysts with variable nanoparticle sizes were obtained by modulating the reduction temperature,and the catalytic activity was evaluated using 1,2,3,4-tetrahydroquinoline and o-propylaniline with different C-N bond hybridization patterns as reactants.Results showed a 13 times higher reaction rate for sp3-hybridized C-N bond cleavage than sp2-hybridized C-N bond cleavage,while the reaction rate tended to increase first and then decrease as the catalyst nanoparticle size increased.Different concentrations of terrace,step,and corner sites were found in different sizes of Ru nanoparticles.The relationship between catalytic site variation and C-N bond cleavage activity was further investigated by calculating the turnover frequency values for each site.This analysis indicates that the variation of different sites on the catalyst is the intrinsic factor of the size dependence of C-N bond cleavage activity,and the step atoms are the active sites for the C-N bond cleavage.When Ru nanoparticles are smaller than 1.9 nm,they have a strong adsorption effect on the reactants,which will affect the catalytic performance of the Ru catalyst.Furthermore,these findings were also confirmed on other metallic Pd/Pt catalysts.The role of step sites in C-N bond cleavage was proposed using the density function theory calculations.The reactants have stronger adsorption energies on the step atoms,and step atoms have d-band center nearer to the Fermi level.In this case,the interaction with the reactant is stronger,which is beneficial for activating the C-N bond of the reactant.
基金Y.A.Kolekar gratefully acknowledges the University Grants Commission(UGC)(New Delhi,India,for the Senior Research Fellowship(SRF)We acknowledge financial support from the DST-sponsored project No.DST/INT/RUS/RSF/P-54/2021.
文摘An efficient Pd/Cu-catalyzed oxidative self-carbonylation of arylhydrazine with CO and molecular oxygen as an oxidant to afford symmetrical biaryl ketones via C—N bond activation has been developed.In this approach,arylhydrazine hydrochlorides are used as a green arylating agent which releases nitrogen and water as byproducts.This developed protocol significantly restricts the formation of aryl iodide and homo-coupled azobenzene products even under favorable conditions.A library of symmetrical biaryl ketones with wide functionalities was synthesized in good yields under mild conditions.
