- Dehydrogenative Coupling of Ethanol and Ester Hydrogenation Catalyzed by Pincer-Type YNP Complexes
-
The "Y" donor group (Y = -OMe, -SEt, -PPh2, -NH2, -NMe2, -Py, pyrrolidinyl, quinolyl) of the pincer-type ruthenium complexes RuHCl(CO)[κ3-YNP] has a dramatic influence on the catalytic activity in the dehydrogenative homocoupling and cross-coupling of ethanol and ester hydrogenation reactions. The observations are connected with the mechanisms of the catalytic reactions, and this paper provides evidence for ester C-O bond formation/cleavage assisted by the bifunctional catalysts in an outer-sphere fashion, reminiscent of the Tishchenko chemistry.
- Gusev, Dmitry G.
-
p. 6967 - 6981
(2016/10/14)
-
- Investigations into the mechanism of the liquid-phase hydrogenation of nitriles over Raney-Co catalysts
-
The co-hydrogenation of acetonitrile and butyronitrile over Raney-Co was investigated in order to obtain insight into the mechanism underlying the formation of secondary amines. Acetonitrile was reduced much faster to the corresponding primary amine due to stronger adsorption on the catalyst surface. In parallel, dialkylimines were formed and subsequently converted to secondary amines. It is suggested that the dialkylimines are formed by reaction of partially hydrogenated intermediate species on the cobalt surface with amines. In this respect, n-butylamine was found to react much faster than ethylamine. The stronger inductive effect of the butyl chain is thought to facilitate nucleophilic attack of the amine at the α-C-atom of the surface species. By comparing the C2 and C4 balance for dialkylimines and dialkylamines, it was found that direct hydrogenation of the dialkylimine cannot be the only way of dialkylamine formation. Instead, it is suggested that alkyl group transfer occurs by reaction of a monoalkylamine with a dialkylimine and cross-transfer between two dialkylimines.
- Schaerringer, Peter,Mueller, Thomas E.,Lercher, Johannes A.
-
p. 167 - 179
(2008/09/17)
-