title: Density functional theory study of the carbonyl-ene reaction of encapsulated formaldehyde in Cu(I), Ag(I), and Au(I) exchanged FAU zeolites.
abstract: Carbonyl-ene reactions, which involve C-C bond formation, are essential in many chemical syntheses. The formaldehyde-propene reaction catalyzed by several of the group 11 metal cations, Cu(+), Ag(+), and Au(+) exchanged on the faujasite zeolite (metal-FAU) has been investigated by density functional theory at the M06-L/6-31G(d,p) level. The Au-FAU exhibits a higher activity than the others due to the high charge transfer between the Au and the reactant molecules, even though it is located at a negatively charged site of the zeolite. This site enables it to compensate for the charge of the Au(+) ion. The NBO analysis reveals that the 6s orbital of the Au atom plays an important role, inducing a charge on the probe molecules. Moreover, the effect of the zeolite framework makes the Au-FAU more active than the others by stabilizing the high charge induced transition structure. The activation energy of the reaction catalyzed by Au-FAU is 13.0 kcal/mol whereas that of Cu and Ag-FAU is found to be around 17 kcal/mol. The product desorption needs to be improved for Au-FAU; however, we suggest that catalysts with high charge transfer might provide a promising activity.
authors.affiliation: Department of Chemistry, Faculty of Science and Center of Nanotechnology, Kasetsart University Research and Development Institute, Kasetsart University, Bangkok, Thailand.
authors.forename: Sippakorn
authors.initials: S
authors.lastname: Wannakao
authors.forename: Pipat
authors.initials: P
authors.lastname: Khongpracha
authors.forename: Jumras
authors.initials: J
authors.lastname: Limtrakul
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D005557:Formaldehyde / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D011789:Quantum Theory; D012834:Silver / Q000737:chemistry; D017641:Zeolites / Q000737:chemistry
chemical_list: D000475:Alkenes; D009942:Organometallic Compounds; D017641:Zeolites; D005557:Formaldehyde; D012834:Silver; D006046:Gold; D003300:Copper; C013658:propylene