Supported organoactinide complexes as heterogeneous catalysts. A kinetic and mechanistic study of facile arene hydrogenation

Journal Article · Wed Dec 16 04:00:00 EST 1992 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00052a036· OSTI ID:6394976

Eisen, M S; Marks, T J ^[1]

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1. Northwestern Univ., Evanston, IL (United States)

This contribution reports a kinetic and mechanistic study of arene hydrogenation by the supported organoactinide complexes Cp[prime]Th(benzyl)[sub 3]/DA (1/DA), Th(1,3,5-CH[sub 2]C[sub 6]H[sub 3]Me[sub 2])[sub 4]/DA (2/DA), and Th([eta][sup 3]-allyl)[sub 4]/DA (3/DA) where Cp[prime] = [eta][sup 5]-Me[sub 5]C[sub 5] and DA = dehydroxylated [gamma]-alumina. In slurry reactions (90[degrees]C, P[sub H[sub 2]] = 180 psi), the activity for benzene hydrogenation follows the order 1/DA < 2/DA < 3/DA with an N[sub t] value for 3/DA of [approximately]25,000 h[sup [minus]1] active site[sup [minus]1]. This approaches or exceeds most conventional platinum metal catalysts in efficacy for benzene reduction. Partially hydrogenation products cannot be detected at partial conversions, and there is no D[sub 2] incorporated in the unconverted benzene. D[sub 2] is not delivered to a single benzene face, but rather a 1:3 mixture of all-cis and cis,cis,trans,cis,trans isotopomers is formed. Active site characterizations using D[sub 2]O poisoning, hydrogenolysis, and CH[sub 3]Cl dosing indicate that [le]8 [plus minus] 1% of the Th surface sites are responsible for the bulk of the benzene hydrogenation. EPR and XPS studies provide no evidence for surface Th oxidation states less than +4. As a function of arene, the relative rates of Th([eta][sup 3]-C[sub 3]H[sub 5])[sub 4]/DA-catalyzed hydrogenation are benzene > toluene > p-xylene > naphthalene, with the regiochemistry of p-xylene reduction similar to that for benzene. Experiments with 1:1 benzene-p-xylene mixtures reveal that benzene is preferentially hydrogenated with almost complete exclusion of p-xylene ([approximately]97:3), inferring that the benzene binding constant to the active sites is [approximately]6.7[times] that of p-xylene. 51 refs., 8 figs., 2 tabs.

• DOE Contract Number: FG02-86ER13511
• OSTI ID: 6394976
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 114:26; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702* -- Radiochemistry &amp; Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPOUNDS
ALKYLATED AROMATICS
AROMATICS
BENZENE
CATALYSIS
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CONDENSED AROMATICS
DEUTERIUM
ELECTRON SPECTROSCOPY
ELECTRON SPIN RESONANCE
ELEMENTS
HETEROGENEOUS CATALYSIS
HYDROCARBONS
HYDROGEN ISOTOPES
HYDROGENATION
ISOTOPES
KINETICS
LABELLING
LIGHT NUCLEI
MAGNETIC RESONANCE
METALS
NAPHTHALENE
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXIDATION
PHOTOELECTRON SPECTROSCOPY
PLATINUM
PLATINUM METALS
POISONING
REACTION KINETICS
RESONANCE
SPECTROSCOPY
STABLE ISOTOPES
THORIUM COMPOUNDS
TOLUENE
TRANSITION ELEMENTS
X-RAY SPECTROSCOPY
XYLENES