Correction. Poly(tertiary Phosphines and Arsines). 17. Poly(tertiary Phosphines) Containing Terminal Neomethyl Groups as Ligands in Asymmetric Homogeneous Hydrogenation Catalysts

1981 ◽  
Vol 46 (12) ◽  
pp. 2603-2603
Author(s):  
R King ◽  
J Bakos ◽  
C Hoff ◽  
L Marko
Keyword(s):  
Homogeneous Hydrogenation ◽  
Hydrogenation Catalysts ◽  
Tertiary Phosphines

Studien zum Vorgang der Wasserstoffübertragung, 71 [1] Tertiäre Phosphine mit ortho-ständigen chelatisierungsfähigen funktionellen Gruppen als Co-Katalysatoren der Homogenhydrierung mit Rh(I)-Komplexen/Studies on the Occurrence of Hydrogen Transfer, 71 [1] Tertiary Phosphines with Functional Groups in the ortho-Position Capable for Chelatization as Co-Catalysts of the Homogeneous Hydrogenation with Rh(I)-Complexes

1984 ◽  
Vol 39 (4) ◽  
pp. 504-511 ◽  
Author(s):  
Leopold Horner ◽  
Guido Simons
Keyword(s):  
Hydrogen Transfer ◽  
Phenyl Group ◽  
Steric Effects ◽  
Ortho Position ◽  
Homogeneous Hydrogenation ◽  
Compound A ◽  
Co Catalyst ◽  
Co Catalysts ◽  
Tertiary Phosphines ◽  
Tertiary Arsines

By systematic variation of the structure of tertiary phosphines with ortho-phenyl substituted groups as co-catalysts of the homogeneous hydrogenation with Rhodium complexes and hexene-1 as a model compound a collection of data is obtained. By investigating the influence of the variation of the Rhodium/Phosphine-Ratio (Rh/P) (1:1,1 and 1:2,2) on the rate of the hydrogentransfer indirect conclusion can be drawn on the composition of the complexes in the equilibria responsible for the hydrogen transfer.Results: 1. Steric effects of substituents linked to the ortho-position of a phenyl group in the co-catalyst are very important (compare the Tables I-V especially Table VI).2. The rate of hydrogenation is strongly influenced by tertiary phosphines with substituents in a ortho-phenyl group capable for coordination like NR2 and SR. With Rh/P = 1:1,1 the rate of the hydrogenation of hexene-1 is mostly faster as with Rh/P = 1:2,2. Depending on steric effects the rate data can be invers.3. Tertiary arsines with o-dialkylaminophenyl groups are more effective co-catalyst as the corresponding phosphines (Table V).4. Tertiary phosphines with an ortho-alkylmercaptophenyl group (38-41) are weakly active cocatalysts using Rh/P = 1:1,1.The thioether 42 (in compounds 12 the diphenylphosphino group is exchanged by the methylmercapto group) is also a moderate active co-catalyst.5. As a conclusion: it is assumed that complexes of the structure A can coordinate with the substrates hydrogen and olefine . Complexes of the structure B seen to be to stable for the activation of the substrates.

Rhodium(I) complexes of β-diketonates and related ligands as homogeneous hydrogenation catalysts

1991 ◽  
Vol 66 (3) ◽  
pp. 251-269 ◽  
Author(s):  
William R. Cullen ◽  
Steven J. Rettig ◽  
Eugene B. Wickenheiser
Keyword(s):  
Homogeneous Hydrogenation ◽  
Hydrogenation Catalysts

KINETIC STUDIES OF CHLORO COMPLEXES OF RHODIUM AS HYDROGENATION CATALYSTS

1966 ◽  
Vol 44 (2) ◽  
pp. 233-242 ◽  
Author(s):  
B. R. James ◽  
G. L. Rempel
Keyword(s):  
Maleic Acid ◽  
Kinetic Studies ◽  
Homogeneous Catalyst ◽  
Ferric Ion ◽  
Homogeneous Hydrogenation ◽  
Acid Complex ◽  
Olefinic Bond ◽  
Hydrogenation Catalysts ◽  
Chloro Complexes ◽  
Anionic Complexes

The anionic complexes [RhCl6]3−, [Rh(H2O)Cl5]2−, and [Rh(H2O)2Cl4]− activate molecular hydrogen for the reduction of ferric ion in aqueous acid solution; the catalytic activity increased with increasing number of chloride ligands present. Cationic and neutral chloroaquorhodium(III) complexes did not homogeneously catalyze the reduction of ferric ion, the complexes themselves being reduced to metallic rhodium, a powerful heterogeneous catalyst.Chloro complexes of rhodium(III) and rhodium(I) were not effective catalysts in aqueous solution for the homogeneous hydrogenation of the olefinic bond in maleic acid. Anionic chlororhodate(III) complexes were reduced by hydrogen to the univalent state, this state being stabilized against further reduction to the metal by complexing with the maleic acid present. Preliminary studies indicate that in dimethylacetamide solution rhodium (III) trichloride is an effective homogeneous catalyst for the reduction of maleic acid to succinic acid by hydrogen, the reaction proceeding through a rhodium (I) – maleic acid complex.

scholarly journals Abbau von Induktionsperioden und Steigerung der Aktivität homogener Hydrierungskatalysatoren mit Iridium als Zentralatom / Reduction of Induction Periods and Increase of Activity of Homogenous Iridium Hydrogenation Catalysts

1978 ◽  
Vol 33 (9) ◽  
pp. 997-1000 ◽  
Author(s):  
Erich Hitzel
Keyword(s):  
Induction Period ◽  
Homogeneous Hydrogenation ◽  
Hydrogenation Catalysts ◽  
Induction Periods

With complexes of iridium as catalysts, induction periods are typical for homogeneous hydrogenation of olefins in bulk. The induction period decreases, as a rule with increasing activity, at higher temperatures and may be suppressed with dibenzoylperoxide, azobisisobutyrodinitrile, tetrachloro-1,4-benzoquinone or by preactivation. Triethylamin and SnCl2 · 2H2O are unsuitable additives. The operation “preactivation” leads additionally to great substrate/catalyst-turnover numbers.

Sign in / Sign up

Export Citation Format

Share Document