School of Engineering and Science - Jacobs University

°C). The stirring speed was 300 rpm. The ethyl pyruvate was added to 70 ml of acetic
acid, then the mixture was sonicated for 10 min, Ar was then flushed through the
solution for 10 min to remove dissolved air. The required amount of catalyst was
added, the mixture was sonicated for 5 min, transferred into the reactor, flushed with Ar
for 10 min and finally after the pressure of hydrogen had been stabilized for 10-15 sec
the initial time (t=0) was set and the reaction kinetics were monitored. Around one ml
aliquots of the reaction mixture were taken at certain time intervals, filtrated with a G4
filter and 1 μl was injected into the gas chromatograph (GC).
FTIR spectra of D type of catalyst were measured with a “Thermo Nicolet Avatar”
spectrometer in transmission mode, resolution 4 cm -1 , number of scans 500. IR pellets
were prepared by mixing 100 mg KBr and 1.5 mg sample then pressing into a pellet
under a pressure of 10 tons. For IR investigation of the B type of catalyst a “Thermo
Nicolet 4700 FT-IR” spectrometer with liquid nitrogen cooled detector and DRIFT
accessory was used with the following parameters: 3000 scans, 600-2000 cm -1 scan
range, 4 cm -1 resolution. The DRIFT spectra were chosen for analysis because it is the
more applicable technique for observing adsorbed species on finely divided metal
powder [174].
The carbon and nitrogen elemental analysis measurements were done on a Carlo Erba
NA2500 C/N analyzer in the School of GeoSciences at Grant Institute in the University
of Edinburgh. Measurements were repeated several times with an error ~1%. The metal
content was found from thermogravimetric Analysis (TGA) in 30-1200 °C temperature
interval under nitrogen 100 ml/min with an SDTQ 600 instrument from TA
Instruments.
The cumulative enantiomeric excess (ee) was calculated according to the formula
[ R]
− [ S]
ee = ⋅100%
.
[ S]
+ [ R]
The actual enantiomeric excess (ee*) was calculated by the previously established
[169] formula
ee y − ee y
ee
*
i+
1 i+
1 i i
i+
1 / 2
=
,
yi+
1
− yi
where y i - mol of both ethyl lactates, ee –cumulative (observed) enantiomeric excess.
Computational methods: Geometry optimization and calculation of IR spectra of
cinchonidine and quinoline were carried out using the Gaussian 03 program [175].
Density functional theory (DFT) calculations were performed by using the B3LYP/6-
31G method and basis set. The vibrations and orientations of dipole moment were
visualized with GaussView and MOLDEN programs.
4.3 Results and discussion
4.3.1 General characterization
Choice of conventional catalyst
The Engelhard 4759 (5% Pt/Al 2 O 3 ) is known from 90 th to be one of the most studied
catalyst for Orito reaction, however the Engelhard company does not produce one any
more and it is not widely available. Due to this reason and the fact that under the same
reaction conditions (Table 4-1) catalyst from Aldrich demonstrates higher
enantioselectivity and reaction rate, we chose it to be the basic conventional catalyst for
further comparisons.
31