Ferenc Ungváry

Octacarbonyl dicobalt-catalyzed selective transformation of ethyl diazoacetate into organic products containing the ethoxycarbonyl carbene building block

Abstract In the presence of 1xa0mol% octacarbonyl dicobalt ethyl diazoacetate can be transformed at room temperature and carbon monoxide pressure selectively into diethyl 2-diazo-3-oxo-pentanedicarboxylate or in the presence of an alcohol (methanol, ethanol, tert -butanol), phenol or diethylamine into the corresponding malonic acid derivatives in high yields. Ethoxycarbonylcarbene-bridged dicobalt carbonyl complexes [μ 2 -{ethoxycarbonyl(methylene)}-μ 2 -(carbonyl)-bis(tricarbonyl-cobalt)( Co – Co )] and [di-μ 2 (ethoxycarbonyl(methylene)}-bis(tricarbony-cobalt)( Co–Co )] proved to be intermediates in the catalytic reactions.

Application of transition metals in hydroformylation annual survey covering the year 2001

Hydroformylation in homogeneous and heterogeneous systems, and hydroformylation related reactions of carbon monoxide reported in 2001 are reviewed.

Grignard reagent formation from aryl halides. There is no aryl radical intermediate along the dominant reaction channel

Abstract For Grignard reagent formation from magnesium and an aliphatic halide RX in an ether solvent, a route through R is the major pathway. Part of the evidence is that by-products of side reactions of R are formed in substantial yields. Similar reactions of phenyl and o -(3-butenyl)phenyl halides give very low (sometimes trace) yields of by-products derived from side reactions of R , despite the fact that aryl R are much more reactive than alkyl in both solvent attack and cyclization [ o -(3-butenyl)phenyl case]. Grignard reactions of aryl halides appear to proceed largely through a pathway along which R is not an intermediate. This is probably a dianion pathway, that is, one along which RX 2− is an intermediate or transition state.

Application of transition metals in hydroformylation: annual survey covering the year 1996

Abstract Hydroformylation in homogeneous and heterogeneous systems, and hydroformylation related reactions of carbon monoxide are reviewed.

Application of transition metals in hydroformylation annual survey covering the year 2002

Hydroformylation in homogeneous and heterogeneous systems, and hydroformylation related reactions of carbon monoxide reported in 2002 are reviewed.

Transition-metal alkyls and hydrides II. Investigation of a complex cobalt hydride obtained from cobalt stearate and grignard reagents1

Abstract Cobalt stearate and alkylmagnesium halides react to form a dark brown homogeneous solution which catalyses the hydrogenation of olefins at Mg:Co ratios of 3-8:1. Cobalt was shown to be present in the form of a complex dihydride L x CoH 2 , formed, presumably, by unstable cobalt alkyls splitting off the alkyl group in the form of an olefin. Besides having cataltic activity, this complex cobalt hydride stoichiometrically hydrogenates alkenes to alkanes. Unsaturated alkoxy-magnesium halides formed from the stearate group are proposed as ligands ensuring the solubility of the complex hydride in hydrocarbon-ether mixtures.

Application of transition metals in hydroformylation annual survey covering the year 1998

Abstract Hydroformylation in homogeneous and heterogeneous systems, and hydroformylation related reactions of carbon monoxide are reviewed.

REACTION OF COBALT TETRACARBONYL HYDRIDE WITH PHENYLACETYLENE

Abstract In C6H6 or hexane at room temperature, under an atmosphere of CO, excess HCo(CO)4 reacts with phenylacetylene to give ethylbenzene and 2-phenylpropanal, the same products that result from the similar reaction of styrene. This and other evidence show that styrene is an intermediate. However, when phenylacetylene is in large excess, neither ethylbenzene, 2-phenylpropanal, nor styrene is formed in more than trace quantity. Instead, a compound is formed whose spectral properties suggest that it is an alkyl- or acylcobalt carbonyl containing a 1-phenylethenyl group. This compound reacts with HCo(CO)4 to give styrene. CIDNP suggests that the reaction of phenylacetylene with HCo(CO)4 proceeds through radical pairs [1-phenylethenyl··Co(CO)4].

Stoichiometric hydrogenations using tetracarbonylcobaltate(—I)

Abstract Methanolic solutions of tracarbonylcobaltate(—I) in the presence of an acid are simple and useful reducing agents for the selective hydrogenation of conjugated carbon-carbon double bonds. The reaction has the following stoichiometry:

Infrared spectra of isotopically substituted XCO(CO)4 (X = H, EtC(O), EtOC(O) and EtOC(O)CH2) molecules

Abstract In this paper we present a series of observations on the infrared spectra of DCo(CO) 4 (in comparison with HCo(CO) 4 ) as well as of the l3 CO-exchanged derivatives of HCo(CO) 4 , EtOC(O)CH 2 Co(CO) 4 , EtOC(O)Co(CO) 4 and EtC(O)Co(CO) 4 . Calculated frequencies and intensities for HCo( 12 CO) n ( 13 CO) 4− n based on the C–O factored force field approximation predict data in excellent agreement with that observed experimentally. Splitting of the E band in the complexes R–Co(CO) 4 is shown to depend on reduction of local site symmetry and appears to be greatest for R groups containing a local dipole capable ‘of through-space’ interaction with the three equatorial carbonyls. The analysis of the infrared absorption bands for the l3 CO-substituted compounds sheds light on the nature of bonding and symmetry of these molecules, and the extent of interaction between the organic substituent and the four CO groups in the cobalt tetracarbonyl compound.