P. Serp et al., RHODIUM-CATALYZED HYDROCARBONYLATION OF ACETIC-ACID INTO HIGHER ACIDS, Journal of molecular catalysis. A, Chemical, 136(3), 1998, pp. 269-278
The hydrocarbonylation of acetic acid into higher homologues catalyzed
by rhodium/iodide systems has been investigated at 20 MPa and 220 deg
rees C. In homogeneous catalysis the most convenient precursor proved
to be [RhI2(CO)(2)](-) prepared from [RhCl(CO)(2)](2) in the presence
of LiI; mean turnover frequencies of 67 h(-1) and selectivities as hig
h as 80% in propionic acid were obtained. In addition, in heterogeneou
s catalysis, rhodium supported upon activated carbon was observed to b
e an efficient system for the conversion of acetic acid into propionic
acid (80% selectivity) in a fixed bed reactor. The reaction mechanism
is thought to be an iodoacetyl rather than an ethanol pathway in the
homogeneous system, while the two seem likely to be in operation in th
e heterogeneous system. (C) 1998 Elsevier Science B.V. All rights rese
rved.