Rhodium-catalyzed aldol-type chemistry under syngas: Selective reductive dimerizations of aldehydes to monoaldehydes and further oxidation to nor-ketones

Journal Article · Sun May 01 04:00:00 EDT 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1994.1120· OSTI ID:7036579

Noels, A F; Messere, R; Fontaine, M; Demonceau, A ^[1]

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1. Universite de Liege, Sart Tilman (Belgium)

Under a pressure of syngas in pyridine, RhCl(PPh[sub 3])[sub 3] selectively catalyzes the dimerization of enolizable C[sub n] aldehydes, possessing one methylene group in the [alpha]-position to the aldehyde function, into saturated dimers, C[sub 2n] monoaldehydes. The yields are good to moderate. The pressure and relative composition of syngas, together with the use of a triphenylphosphine-ligated metal complex are crucial for obtaining good selectivities. Monosubstitution of the [alpha]-carbon severely limits the dimerization. Alcohols and aromatic aldehydes do not react. A tentative reaction mechanism is proposed in which water is involved. The dimer aldehydes can subsequently be oxidized in situ by air or various oxidants such as m-chloroperbenzoic acid or t-butylhydroperoxide into the corresponding nor-ketones. This process constitutes a novel access to such ketones. 27 refs., 5 figs., 4 tabs.

• OSTI ID: 7036579
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 147:1; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

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