Catalytic hydrogenation of aromatic hydrocarbons. Stereochemical definition of the catalytic cycle for eta/sup 3/-C/sub 3/H/sub 5/Co(P(OCH/sub 3/)/sub 3/)/sub 3/

Journal Article · Wed Feb 11 04:00:00 EST 1981 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00393a011· OSTI ID:6644373

Bleeke, J R; Muetterties, E L

The eta/sup 3/-C/sub 3/H/sub 5/Co(P(OCH/sub 3/)/sub 3/)/sub 3/-catalyzed hydrogenations with D/sub 2/ of a series of unsaturated organic molecules, including cyclohexenes, cyclohexadienes, and arenes, have been investigated. Complete cis stereoselectivity was observed in the addition of deuterium to the unsaturated ring systems. When alkyl-substituted arenes were reduced with D/sub 2/, the hydrogen atoms in the alkyl chains underwent H-D exchange as long as each successive carbon atom in the chain possessed at least one hydrogen atom. Hence, extensive H-D exchange occurred in n-alkyl side chains while the tert-butyl side chain was deuterium free. When alkyl-substituted arenes were hydrogenated in the presence of olefins such as 1-hexene, a variety of isomeric alkylcyclohexenes and alkenylcyclohexanes were observed. The relative concentrations of these isomeric species provided information about the relative stabilities of the (olefin)cobalt species in the catalytic cycle. Further mechanistic information was obtained from other competitive reactions, i.e., hydrogenation reactions involving equimolar quantities of two different unsaturated molecules. The proposed initiation steps of the catalytic cycle have been revised on the basis of a study of eta/sup 3/-C/sub 8/H/sub 13/Co(P(OCH/sub 3/)/sub 3/)/sub 3/ as a catalyst precursor. The cyclooctenyl-cobalt bond was cleaved by hydrogen early in the reaction, leaving the highly coordinately unsaturated hydride, HCo(P(OCH/sub 3/)/sub 3/)/sub 2/, which is probably the true catalytic species.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 6644373
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 103:3; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400303* -- Organic Chemistry-- Isotope Exchange & Isotope Separation-- (-1987)
ALKENES
AROMATICS
CATALYSIS
CATALYTIC EFFECTS
CHEMICAL REACTIONS
COBALT COMPLEXES
COMPLEXES
CYCLOALKENES
DEUTERATION
DEUTERIUM
HYDROCARBONS
HYDROGEN ISOTOPES
HYDROGENATION
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES