Res. Chem. Intermed.
, Vol. 29, No. 1, pp. 91–105 (2003)
Also available online - www.vsppub.com
The kinetics of enantioselective hydrogenation of methyl
acetoacetate using a modi ed Raney nickel catalyst
PAVEL KUKULA and LIBOR
Department of Organic Technology, Institute of Chemical Technology (ICT Prague), Technická 5,
166 28 Prague 6, Czech Republic
Received 12 April 2002; accepted 26 September 2002
Abstract—The kinetics of enantioselectivehydrogenationof methyl acetoacetate using Raney nickel
modi ed by (2R,3R)-(
)-tartaric acid were studied, thereby focusing on the effects of the reaction
conditions on the enantioselectivity. Reactions were carried out in a liquid phase under atmospheric
and increased hydrogen pressure. The reaction course was described by the exponential kinetics
model and by Langmuir– Hinshelwood kinetics assuming the existence of two types of active sites on
the catalyst surface, selective and non-selective. Using Langmuir–Hinshelwood kinetics, the acquired
parameters were used for discussion of the effects of the reaction conditions on the enantioselectivity
and the mechanism of the enantioselectivehydrogenation.
: Enantioselectivehydrogenation; reaction kinetics; modi ed Raney nickel; tartaric acid.
The enantioselective hydrogenation of methyl acetoacetate (MAA, Scheme 1) over
chirally modi ed nickel catalysts has become the model reaction for the study of
the properties of these catalysts [1–5]. In this type of heterogeneous catalytic
hydrogenation, a chiral molecule (modi er) suitably implemented to the surface
of the nickel catalyst represents the source of chirality. In particular, tartaric acid
has become the most utilized modi er for nickel catalysts . Many different
types of nickel catalysts have been tested in the enantioselective hydrogenation:
Raney nickel [2, 3], as well as certain supported nickel catalysts [6–14], bi-metallic
supported catalysts [15–22] and nickel powder [2, 4, 23]. As it was already
found during the catalyst modi cation using tartaric acid [5, 24– 26], its corrosive
chemisorption and formation of a complex of nickel and tartaric acid occur on the
catalyst surface. This complex probably serves as the enantioselective active site,
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