Solvent-separated, tight and contact ion-pairings of the M+[Ru(CO)3− I3]− (M = alkali ion) system are produced by reaction of Ru(CO)4I2 with MI in different solvents. The X-ray structure of [K-18-crown-6]+[Ru(CO)3I3]− shows that the contact of the K atom with the anion takes place at the equatorial I groups. Important effects of the ion-pairing of M+[Ru(CO)3I3]− catalysts on the activity and selectivity of CO + H2 reactions on methyl acetate (carbonylation to acetic acid, homologation to ethyl acetate and hydrogenation to methane) are observed. The availability of I− for the formation of [Ru(CO)3I3]− from the iodide promoter and for the activation of the substrate, and the possible Lewis acid activation by M+ ions of the carbon monoxide toward alkyl migration (CO insertion) and of the acyl intermediate toward the nucleophilic attacks of water and alcohols, greatly affect the reaction rate and improve the selectivity to ethyl acetate + acetic acid up to 90–92%, simultaneously reducing the formation of hydrocarbons.
|Autori:||RASPOLLI GALLETTI A M; BRACA G; SBRANA G; MARCHETTI F|
|Titolo:||Homologation of methyl acetate to ethyl acetate with ruthenium catalysts. Part I: Effect and role of ion-pairing|
|Anno del prodotto:||1985|
|Digital Object Identifier (DOI):||10.1016/0304-5102(85)85082-3|
|Appare nelle tipologie:||1.1 Articolo in rivista|