Chiral supported ionic liquid phase (CSILP) catalysts for greener asymmetric hydrogenation processes

Article abstract of DOI:10.1016/j.cattod.2012.06.020

Chiral supported ionic liquid phase (CSILP) catalysts were prepared by physical adsorption (within highly porous carbons or mesoporous silica) of Ir, Ru and Rh complexes as IrCl(COD)-(S,S)-BDPP, [IrCl-(S)-BINAP]₂, RuCl(p-cymene)[(S,S)-Ts-DPEN],

Full text of DOI:10.1016/j.cattod.2012.06.020

Catalysis Today 200 (2013) 63–73
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Catalysis Today
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Chiral supported ionic liquid phase (CSILP) catalysts for greener asymmetric
hydrogenation processes
Iunia Podoleana, Christopher Hardacreb, Peter Goodrichb, Nicolas Brunc, Rénal Backovc,
Simona M. Comana, Vasile I. Parvulescua,∗
a Department of Organic Chemistry, Biochemistry and Catalysis, Faculty of Chemistry, University of Bucharest, Bdul Regina Elisabeta, 4-12, Bucharest 030016, Romania
b School of Chemistry and Chemical Engineering/QUILL, Queen’s University, Belfast BT9 5AG, UK
c Universite de Bordeaux, CRPP-UPR CNRS 8641, 115 Avenue Albert Schweitzer, 33600 Pessac, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Chiral supported ionic liquid phase (CSILP) catalysts were prepared by physical adsorption (within
highly porous carbons or mesoporous silica) of Ir, Ru and Rh complexes as IrCl(COD)-(S,S)-BDPP,
[IrCl-(S)-BINAP]2, RuCl(p-cymene)[(S,S)-Ts-DPEN], RuOTf(p-cymene)[(S,S)-Ts-DPEN], [Rh(COD)(S,S)-
DIPAMP][BF4], and [Rh(COD)(R,R)-Me-DuPHOS][BF4]. For the syntheses of CSILP catalysts [EMIM][NTf2],
[BMIM][BF4] and [BMIM][PF6] ionic liquids were used. Comparative homogeneous and heterogeneous
Received 29 March 2012
Received in revised form 8 June 2012
Accepted 21 June 2012
Available online 21 July 2012
experiments were carried out using the asymmetric hydrogenation of double
C
N
and
C C
Keywords:
Ionic liquids
Chiral complexes
MCM-41
bonds in trimethylindolenine, 2-methylquinoline and dimethylitaconate, respectively. The conversion
and enantioselectivity was found to depend on the nature of the complex (metal and ligand), the immo-
bilization method used, nature of the ionic liquid, nature of the support and the experimental conditions.
Carbonaceous foams
Asymmetric hydrogenation
© 2012 Elsevier B.V. All rights reserved.
1. Introduction
upon inorganic or organic carriers, which is a quite complicated
procedure which does not always provide the desired enantiose-
Asymmetric hydrogenation is an attractive method for the syn-
thesis of chiral intermediates used in the preparation of many
biologically active compounds. Although in the last few decades
great advances have been achieved in the highly enantioselective
hydrogenation of prochiral alkenes and ketones, limited progress
has been made in the asymmetric hydrogenation of imines [1–4].
The literature related to enantioselective hydrogenation of prochi-
ral imines has mostly focused on iridium [5–11], rhodium [12,13]
and ruthenium-based metal complexes [14–18] with chiral ligands
as typical Noyori–Ikariya ligand and DPEN (DPEN = (1R,2R)-(+)-1,2-
diphenylethylenediamine) [19–23]. One of the main drawbacks in
homogeneous catalysis is the difficulty to separate the reaction
products from the soluble catalyst and any solvent. This problem
becomes even more crucial when expensive noble metal and/or
valuable ligand based catalysts are involved. In order to circum-
vent these difficulties many studies have been performed in order
to immobilize expensive enantioselective homogeneous catalyst
systems [24–27]. Unlike the chemical grafting of the chiral ligands
lection [28,29], immobilization of the metal complex catalysts [30]
combines the advantages of both homogeneous and heterogeneous
catalysis.
In the last decade, ionic liquids (ILs) have been used for an
increasing range of catalytic applications [31]. This medium has
become very attractive for both mono- and biphasic processes and
also provides an efficient method of immobilizing transition metal
catalysts [32–35]. More recently, thin layers of an IL deposited on
a porous solid has been shown to be effective in supporting homo-
geneous catalysts. The resulting heterogeneous system has been
defined as supported ionic liquid phase (SILP) catalysts and has
already found multiple applications with good results in terms
of both selectivity and activity [36]. Importantly, an appropriate
combination of the support and the ionic liquid/catalyst has led to
SILP materials being developed on a commercial scale [37]. The
use of supported ionic liquid phase catalysis, SILPs, is thus one
of the most elegant and efficient ways to solve the problem of
catalyst recovery which induces energy consumption via distilla-
tion, and to diminish the use of organic solvents that contribute
considerably to Volatile Organic Compounds (VOCs) emissions. To
date, most of SILP catalysts have been prepared on oxide supports
[38–43] but highly porous carbons or carbon nanotubes (CNTs) car-
riers represent an interesting alternative due to: (i) high purity
avoiding self-poisoning, (ii) improved mechanical properties, high
∗
Corresponding author. Tel.: +40 21 4100241; fax: +40 21 4100241.
E-mail addresses: c.hardacre@qub.ac.uk (C. Hardacre),
simona.coman@g.unibuc.ro (S.M. Coman), vasile.parvulescu@g.unibuc.ro,
v parvulescu@yahoo.com (V.I. Parvulescu).
0920-5861/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.cattod.2012.06.020

64
I. Podolean et al. / Catalysis Today 200 (2013) 63–73
and a siliceous MCM-41 (Ssp = 545 m2/g, Dp = 2.7 nm) were prepared
using procedures previously reported [48].
electrical conductivity and thermal stability, (iii) high accessibility
of the active phase and the absence of any microporosity, thus elim-
inating diffusion and intraparticle mass transfer in the reactions
medium, (iv) the possibility of tuning the specific metal-support
interactions which can directly affect catalytic activity and selec-
tivity, and (vi) the possibility of confinement effects in their inner
cavity [44].
Within this paper, the main goal was to develop chiral supported
ionic liquid phase (CSILP) catalysts on highly porous carbons and to
apply them in asymmetric organometallic catalysis, namely, asym-
2.2.3. Ionic liquids
1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)
imide [EMIM][NTf2] (Scheme 2) was prepared using a procedure
reported elsewhere [49] while 1-butyl-3-methylimidazolium
tetrafluoroborate [BMIM][BF4] and 1-butyl-3-methylimidazolium
hexafluorophosphate [BMIM][PF6] were purchased from
Sigma–Aldrich.
metric hydrogenation of double
C
N
and
C
C
bonds. Since
the nature of the support has been demonstrated to have a sig-
nificant influence on the IL/support interaction, which may affect
the catalytic activity, amorphous SiO2 and mesoporous silica (e.g.,
MCM-41) were used for comparison.
2.2.4. Chiral organometallic complexes immobilization
2.2.4.1. CSILP catalysts. The chiral organometallic complexes were
solubilized in the ionic liquids and supported on MCM-41 or
highly porous carbons as follows: a flame dried Schlenk flask was
charged with 50 mg chiral complex dissolved in 25 mL dried and
degassed dichloromethane (CH2Cl2). The resulting solution was
stirred at room temperature until all the complex was dissolved.
To this solution 0.05 mL ionic liquid were added and stirred for
15 min. Then 250 mg solid carrier (previously dried under vacuum
overnight at 100 ◦C) was added and the resulting slurry was stirred
for another 10–15 min at room temperature until the solvent was
totally removed. The resulted CSILP was thoroughly washed with
CH2Cl2 to remove the excess of ionic liquid or chiral complex and
dried under vacuum.
2. Experimental
2.1. General procedures
All syntheses and manipulations were performed under an
inert atmosphere by using standard Schlenk techniques. The
experiments were carried out in a glove-box 850-NB Nitrogen dry-
box from Plas-Labs. Solvents of analytical grade were dried and
degassed under N2 immediately prior to use. All other chemicals
were commercial products (Sigma–Aldrich or Strem) and were
used as received without further purification.
2.2.4.2. Covalently bonded. RuCl(p-cymene)[(S,S)-Ts-DPEN] (C)
was immobilized on the surface of MCM-41 via the cova-
lent grafting methodology (Scheme 3) [50] as follows: 20 mg
RuCl(p-cymene)[(S,S)-Ts-DPEN] (C) complex dissolved in 5 mL
of dry CH2Cl2 was added to a suspension of 100 mg of func-
tionalized MCM-41 in CH2Cl2 and stirred for 24 h, at room
temperature. The solid was separated by filtration, washed with
CH2Cl2 to remove the physically adsorbed chiral complex and
dried under vacuum. The functionalization of MCM-41 with
(3-aminopropyl)triethoxysilane was obtained as follows: 0.53 g
(2.4 mmol) of (3-aminopropyl)triethoxysilane were dissolved
in 20 mL of anhydrous toluene and mixed with 2 g of MCM-41.
The slurry was heated under reflux for 12 h and cooled at room
temperature, at which point the solid was separated by filtration.
The solid filtrate was finally washed with 50 mL of pentane, 100 mL
of acetonitrile, and 100 mL of diethyl ether and dried under vac-
uum. The same procedure was applied for the covalently bonded
complex (C) onto 25HF support.
2.2. Chiral SILP (CSILP) catalysts preparation
2.2.1. Chiral organometallic complexes
Both commercial and in house prepared chiral organometallic
Ru, Rh and Ir complexes (Table 1 and Scheme 1) were used. Ir-
based complexes IrCl(COD)-(S,S)-BDPP (A, Table 1 and Scheme 1)
and [IrCl-(S)-BINAP]2 (B, Table 1 and Scheme 1) were synthe-
sized as reported elsewhere [45,46]. For IrCl(COD)-BDPP, A: a
mixture of di-␮-chloro-1.5 (COD) di-iridium (0.004 mmol), (S,S)-
BDPP (0.008 mmol) and AgBF4 (0.009 mmol) in 5 mL of methanol
was stirred at room temperature for 24 h in the absence of light.
The resulting AgCl was removed by filtration and the mixture
reduced under vacuum to yield a bright red solid precipitate.
The obtained precipitate was recrystallized in 30 mL of diethyl
ether, washed three times with 3 mL of diethyl ether and dried
overnight under vacuum. [IrCl(S)-BINAP]2 B: the active complex
was made prior to hydrogenation by mixing the iridium complex
IrCl(COD) (0.004 mmol) with BINAP (0.008 mmol) in methylene
chloride at 25 ◦C for 10 min. RuCl(p-cymene)[(S,S)-Ts-DPEN] (C,
Table 1 and Scheme 1) was purchased from Sigma–Aldrich while
RuOTf(pcymene)[(S,S)-Ts-DPEN] (D, Table 1 and Scheme 1) com-
plex was prepared as follows: [RuCl2(p-cymene)]2 (0.5 mmol),
(S,S)-TsDPEN (1 mmol) and 7 mL CH2Cl2 were charged in a Schlenk
and stirred for 5 min at room temperature, then 7 mL of water
was added. The resulting layers were separated and the CH2Cl2
layer was dried with CaCl2, filtered and the CH2Cl2 removed under
reduced pressure. The resulting solid (0.34 mmol) was reacted with
CF3SO3H (TfOH, triflic acid) (0.34 mmol) in 3 mL THF within a
Schlenk tube on stirring for 1 h. The precipitate was filtered and
washed with THF. [Rh(COD)(S,S)-DIPAMP][BF4] (E, Table 1 and
Scheme 1) and [Rh(COD)(R,R)-Me-DuPHOS][BF4] (F, Table 1 and
Scheme 1) complexes were purchased from Strem Chemicals.
2.3. Catalysts characterization
2.3.1. The characterization of the derived complexes
Diffuse reflectance infrared Fourier transform (DRIFT) spec-
tra were collected with a Thermo 4700 spectrometer (200 scans
with a resolution of 4 cm−1) over the range 600–4000 cm−1. DR-
UV–vis spectra were recorded in the UV–vis region using diffuse
reflectance technique with a Specord 250 spectrometer from Ana-
lytik Jena.
2.3.1.1. 1H and 13C NMR. Prepared IrCl(COD)-(S,S)-BDPP (A),
RuOTf(p-cymene)[(S,S)-Ts -DPEN] (D) chiral complexes structures
were verified with 1H and 13C CP MAS NMR technique. Solid-state
MAS NMR experiments were performed on a Bruker AVANCE 400
spectrometer with the appropriate Bruker MAS probe head and
applying different spinning frequencies.
2.3.2. The characterization of the CSILP and covalently bonded
complexes
2.2.2. Supports
Highly porous carbons (25HF, Ssp = 800 m2/g, Dp = 2.2 nm
(Dp = average pore size) and 4F5, Ssp = 600 m2/g, Dp = 2.4 nm) [47]
Surface area and pore size values calculated from nitro-
gen adsorption–desorption isotherms (−196 ◦C) recorded on a

I. Podolean et al. / Catalysis Today 200 (2013) 63–73
65
Table 1
Investigated chiral organometallic Ru, Rh and Ir complexes.
Nr.Crt.
Complex
Chiral ligand
A
B
C
D
E
F
IrCl(COD)/(S, S)-BDPP
[IrCl(S)-BINAP]2
RuCl(p-cymene)[(S,S)-Ts-DPEN]
RuOTf(p-cymene)[(S,S)-Ts-DPEN]
[Rh(COD)(S,S)-DIPAMP][BF4]
[Rh(COD)(R,R)-Me-DuPHOS][BF4]
(2S,4S)-2,4-Bis(diphenylphosphino)pentane
(S)-(−)-(1,1ꢀ-Binaphthalene-2,2ꢀ-diyl)bis(diphenylphosphine)
(1S,2S)-(+)-1,2-Diphenylethylenediamine
(1S,2S)-(+)-1,2-Diphenylethylenediamine
(1S,2S)-(+)-Bis[(2-methoxyphenyl) phenylphosphino]ethane
(−)-1,2-Bis((2R,5R)-2,5-dimethylphospholano)benzene
Micromeritics ASAP-2010 instrument. Calcined samples were
degassed for 15 h at 130 ◦C and 10−6 Torr before analysis. Sur-
face areas were estimated according to the BET model, and pore
size dimensions were calculated using the BJH method. Powder X-
ray diffraction (XRD) measurements were made using a Siemens
D5000 X-ray diffractometer with nickel filt−e1red Cu K␣ radiation
of 10–80◦. Thermogravimetric analysis (TG-DTA) was performed
using a SDT Q600 instrument supplied by TA Instruments. The sam-
ples were placed in a platinum sample holder and heated at a rate
of 10 ◦C min−1 from room temperature to 600 ◦C under a N2 flow
with a rate of 20 mL min−1. Transmission electron microscopy TEM
measurements were performed by placing the materials on a spe-
cial structured 4-nm-thick carbon support film. These thin films
are sufficiently stable to cover copper grids with a mesh of 60 ␮m
without an additional holey organic film. The electron microscopy
investigation was carried out on a Siemens Elmiskop 102 instru-
ment.
Elemental analysis was performed with a EuroEA 3000 auto-
mated analyzer. The sample (less than 1 mg) was weighed in tin
containers and then burned in a vertical reactor (oxidation tube).
This step was carried out in the dynamic mode at 980 ◦C in a He
flow with the addition of O2 (10 mL) at the instant of sample intro-
duction. Portions of the sample in tin capsules were placed in the
˚
(X = 1.5418 A) at a scanning rate of 0.1 min
over the 2ꢀ range
Scheme 1. Structures of the investigated chiral organometallic Ru, Rh and Ir complexes.
CH3
CH3
N+
CH3
N+
N+
F
N-
O
F
O
F
F
F
F
F
F
B-
P-
F
S
F
F
S
F
N
F
F
N
N
O
O
F
F
CH3
CH3
[BMIM][BF4]
CH3
[EMIM][NTf2]
[BMIM][PF6]
Scheme 2. Investigated ionic liquids (ILs) structures.
Scheme 3. Covalent grafting of RuCl(p-cymene)[(S,S)-Ts-DPEN] (C) complex on aminopropyl MCM-41 carrier.

66
I. Podolean et al. / Catalysis Today 200 (2013) 63–73
Fig. 1. 1H and 13C MAS NMR spectra of (a) (2S,4S)-2,4-Bis(diphenylphosphino)pentane ((S, S)-BDPP) chiral ligand and (b) IrCl(COD)/(S, S)-BDPP (A) chiral complex.
automated sampler, from which they were transferred to the oxi-
dation tube at regular intervals. The concentration of each element
was calculated using the Callidus program supplied with the ana-
lyzer.
catalyst was filtered and the filtrate was purified through a silica gel
column using hexane:i-PrOH as eluent. Thereafter, the solvent was
removed under vacuum, at 60 ◦C to provide the purified product.
For comparison, similar tests were performed in homogeneous
catalysis by using 0.014 mmol of chiral organometallic counter-
part complex (S/C = 100) dissolved in 5 mL of CH2Cl2 or 5 mL of
ionic liquid. The reaction products were separated from ionic liq-
uid by extraction with 3× 5 mL of degassed hexane, diethyl ether
or toluene. Then, the ionic liquid containing the catalyst was dried
under vacuum and subjected to a second run.
2.4. Catalytic tests
2.4.1. C N hydrogenation
Typical hydrogenation tests were carried out in a stainless steel
autoclave with internal glass liner of 8 mL capacity. 1.4 mmol of
trimethylindolenine or 2-methylquinoline (quinaldine) dissolved
in 5 mL of CH2Cl2 and 50 mg of solid catalyst were added to the
autoclave and the reactor purged three times with nitrogen. The
reaction mixture was pressurized with molecular hydrogen (30 and
50 bar) and stirred at 1200 rpm between 25 and 50 ◦C for between
5 and 48 h. After the reaction was stopped, the heterogenized solid
2.4.2. C C hydrogenation
A
similar protocol was used for the hydrogenation of
dimethylitaconate. Catalytic tests under hydrogen continuous flow
conditions were done using a Schlenk reactor having a gas-
dispersion tube. Both the chiral organometallic complex and
Fig. 2. 1H and 13C MAS NMR spectra of (a) (1S,2S)-(+)-N-(4-Toluenesulfonyl)-1,2-diphenylethylenediamine ((S,S)-TsDPEN) chiral ligand and (b) RuOTf(pcymene)[(R,R)-Ts-
DPEN] (D) chiral complex.

I. Podolean et al. / Catalysis Today 200 (2013) 63–73
67
Fig. 3. XRD patterns of MCM-41 (a), functionalized MCM-41 (b), and covalently
anchored RuCl(p-cymene)[(S,S)-Ts-DPEN] (C) complex to functionalized MCM-41
(c).
Fig. 4. XRD patterns of the MCM-41 (a), [BMIM][BF4]/MCM-41 (b), and of the CSILP
[BMIM][BF4]-C/MCM-41 catalyst) (c).
the solid catalyst were tested in these conditions using a sub-
strate/catalyst (S/C) ratio of 500 and a constant hydrogen pressure
(0.5–1 bar). When the ionic liquid was used as solvent, the reaction
products were extracted with 3× 5 mL of ethyl ether. The extracted
phase was filtered through a silica gel column and the solvent was
removed under reduced pressure at 60 ◦C.
characteristic of all grafted ordered organo-silicas [48]. The pat-
tern of this sample presents the dominant d1 0 0 reflection that is a
clear evidence of the preservation of the mesoporosity of MCM-41.
The XRD patterns of the CSILP catalysts did not contain any
characteristic lines of the metal complex or of the decomposition
compounds of the metal complex, indicating that, indeed, the final
material contained only dispersed species in the ionic liquid layer
(Fig. 4). The attenuation of the d1 0 0 reflection characteristic for
MCM-41 carrier is again due to the presence of the complex and
ionic liquid and not evidence of degradation of the support.
The XRD pattern of 25HF mesoporous carbon is close to that of
graphite and shows two diffraction lines at 2ꢀ = 23◦ (d0 0 2) and 43.5◦
(d1 0 0) (Fig. 5). Such XRD pattern corresponds to partially graphi-
tized porous carbon monoliths, in accordance with the literature
[52]. As found for the XRD results obtained for MCM-based sam-
ples, the intensity of the X-ray diffraction lines of the 25HF support
decreased after the chiral complex immobilization by physisorp-
tion (CSILP, Fig. 5c). Similar behavior was observed for the 4F5
support (Fig. 5b).
2.4.3. Leaching measurements
The activity of any complex leached from the solid and present
in the solution was examined by initially performing the het-
erogeneously catalyzed reactions at room temperature for 12 h.
Thereafter, half the volume was filtered and the resulting clear solu-
tion which underwent further reaction for another 6 h. The extent
of leaching was estimated by comparing the conversions with and
without the solid catalyst and from elemental analysis of fresh and
spent catalysts.
2.4.4. Product analysis
The reaction products were analyzed by HPLC (Agilent
Technologies apparatus, column: Daicel Chiralpack OD-
H, 25 cm × 4.6 mm, 5 ␮m, eluent: n-hexane/i-PrOH = 95/5,
Q = 1 mL min−1, UV–vis detection: X = 254 nm. All racemic stan-
dards were prepared in accordance with the literature procedure
[51]. The structure of the resulted products was confirmed by 1H
and 13C NMR spectroscopy using a Bruker AV 400 spectrometer,
CDCl3 as solvent and Me4Si as the internal standard.
TEM characterization of these samples was not able to provide
information on the presence of the ionic liquid or of the metal
complexes dispersed in ionic liquids. However, the textural charac-
teristics of the investigated materials indicate the presence of these
phases (Table 2). Nitrogen adsorption–desorption isotherms of the
materials showed typical IV-type shapes as is generally reported
for such mesoporous materials [48].
3. Results and discussion
The variation of the surface areas parallels the intensity of the
d1 0 0 line observed in the XRD patterns. For both supports, the depo-
sition of the ionic liquid (pure or containing the complex) (e.g.,
[BMIM][BF4]-C/MCM-41 and [BMIM][BF4]-C/25HF samples) led to
a drastic decrease of the surface area compared with the bare sup-
port (33% and 17%, respectively). This drop may be related to the
3.1. Catalysts characterization
The 1H and 13C MAS NMR spectra (Figs. 1 and 2) of the chi-
ral ligands (e.g., (2S,4S)-2,4-Bis(diphenylphosphino)pentane
((S,
S)-BDPP)
and
(1S,2S)-(+)-N-(4-Toluenesulfonyl)-1,2-
diphenylethylenediamine ((S,S)-TsDPEN), respectively) and
the corresponding IrCl(COD)-(S, S)-BDPP (A) and RuOTf(p-
cymene)[(S,S)-Ts-DPEN] (D) chiral complexes proved their
successful synthesis. Unfortunately, due to the low loadings of
supported complexes onto carriers this characterization technique
did not allowed their identification in heterogeneous catalysts.
Powder XRD patterns of MCM-41 and functionalized MCM-
41 are presented in Fig. 3. They exhibit only the diffraction lines
of the MCM-41 structure providing good evidence that the two-
dimensional hexagonal symmetry structure of the mesoporous
support was preserved irrespective of the pretreatment, i.e., teth-
ering and extraction of the structure directing agent.
Fig. 5. XRD diffractograms of the 25HF (a), [BMIM][BF4]-C/4F5, physically adsorbed
(CSILP catalyst) (b) and [BMIM][BF4]-C/25HF, physically adsorbed (CSILP catalyst)
(c) samples.
Tethering the RuCl(p-cymene)[(S,S)-Ts-DPEN (C) complex
induced some slight differences in the XRD patterns which are

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I. Podolean et al. / Catalysis Today 200 (2013) 63–73
Table 2
Surface area and pore volume of neat material and supported catalysts.
Entry
Sample
SBET (m2/g)
Pore volume (cm3/g)
1
2
3
4
5
6
7
8
9
25HF
800
671
665
600
346
340
544
370
364
5.6
4.4
4.4
2.4
1.4
1.4
2.6
1.8
1.8
[BMIM][BF4]/25HF
[BMIM][BF4]-C/25HFa
4F5
[BMIM][BF4]/4F5
[BMIM][BF4]-C/4F5a
MCM-41
[BMIM][BF4]/MCM-41
[BMIM][BF4]-C/MCM-41a
a
CSILP catalyst.
Fig. 7. DRIFT spectra of [BMIM][BF4] (a), MCM-41 (b), [BMIM][BF4]/MCM-41 (c), and
[BMIM][BF4]-C/MCM-41, physically adsorbed, (CSILP catalyst) (d).
Fig. 6. DRIFT spectra of RuCl(p-cymene)[(S,S)-Ts-DPEN] (C) complex, (a); MCM-41
support, (b); functionalized MCM-41, (c); and covalently bonded RuCl(p-
cymene)[(S,S)-Ts-DPEN] (C) complex on functionalized MCM-41, (d) (in accordance
with the model described in Scheme 3).
Fig. 8. The TG-DTA profiles for functionalized MCM-41 with aminopropyl groups.
2800–3000 cm−1 range). Nevertheless, although not very intense,
a new vibration band appeared at 3000 cm−1, clearly indicating
the presence of the NH2 groups. However, of more relevance
is the change in the Si OH stretching band at 3745 cm−1 before
and after the functionalization process. The disappearance of
this band (Fig. 6b and c) together with the appearance of all
characteristic bands both of (3-aminopropyl)triethoxysilane and
RuCl(p-cymene)[(S,S)-Ts-DPEN] (C) complex, indicates strongly
that the complex is tethered non-destructively. Moreover, the evo-
lution of this band provides evidence that the MCM-41-complex
interaction occurs through covalent bonds.
DRIFTS analysis of the physically attached RuCl(p-
cymene)[(S,S)-Ts-DPEN] (C) complex on MCM-41 (CSILP catalyst)
also confirmed the presence of both [BMIM][BF4] ionic liquid and
the RuCl(p-cymene)[(S,S)-Ts-DPEN] (C) complex (Fig. 7). Due to
the higher loading of the complex in this case, compared with the
tethered complex, the characteristic bands are significantly more
intense, in this case.
blocking of the pores by the [BMIM][BF4] ionic liquid. These values
also confirm the formation of CSILP because, after the deposition of
the ionic liquids, these solids still exhibit a free pore volume. The
decrease in the volume of the mesopores was also correlated with
the reduction in the surface area. Moreover, during the grafting
process, a fraction of IL may have become attached to the exter-
nal surface of MCM-41 and part of the mesopores may have been
destroyed in this process, leading to the formation of macropores, in
accordance with previous studies [48]. Such processes can explain
the differences in the intensities of the XRD patterns (see Fig. 4).
However, the textural characterization provides evidence on the
formation of CSILP irrespective of the changes produced in the
texture of the support during functionalization. As expected, the
XRD suggests that the 25HF support has a higher stability than 4F5
(Fig. 5).
The presence of the chiral complex (e.g., RuCl(p-cymene)[(S,S)-
Ts-DPEN] (C), Table 1, entry 6) in the ionic liquid did not lead to any
further decrease in the surface area or the pore volume showing
the chiral complex remains, indeed, suspended in the ionic liquid
and does not separately migrate onto the support. Similar effects
were also observed in the case of 25HF and 4F5 mesoporous carbon
as supports (Table 2, entries 1–6).
DRIFTS analysis of the physically and covalently bonded
RuCl(p-cymene)[(S,S)-Ts-DPEN] (C) complex on MCM-41 support
confirmed the presence of both the [BMIM][BF4] ionic liquid and
of the complex (Figs. 6 and 7). Due to the low concentration
of the tethering agent ((3-aminopropyl)triethoxysilane) on the
MCM-41 surface, the intensity of the bands associated with the
CH2 groups in the functionalized MCM-41 is weak (Fig. 6,
Table 3 summarizes all of the bands identified for the phys-
ically and covalently bonded RuCl(p-cymene)[(S,S)-Ts-DPEN] (C)
complex on MCM-41.
The as-synthesized systems were also investigated by combined
TG-DTA measurements (Figs. 8–10). The functionalized amino-
propyl mesoporous silica decomposed in a relatively well defined
manner and released defined fragments (Fig. 8). The mass loss
together with the enthalpy effects is given in Table 4.
The main mass loss (4.12%) corresponds to the decomposition
of aminopropyl entities. Weight loss at temperatures below 100 ◦C
usually corresponds to the loss of physically adsorbed water loss
while the loss at higher temperatures (451–721 ◦C) is due to the
dehydroxylation of the Si OH groups. The percentage of 4.12%
mass loss of aminopropyl entities decomposition indicates that

I. Podolean et al. / Catalysis Today 200 (2013) 63–73
69
Table 3
Frequency and group assignments for physically [BMIM][BF4]-C/MCM-41 (CSILP) and covalently bonded RuCl(p-cymene)[(S,S)-Ts-DPEN] (C) complex on MCM-41.
Wavenumber (cm−1
)
Group assignment
MCM-41
Comments
Covalently
CSILP
–
3745 (s)
Free silanol hydroxyl band, str
–
Si OH stretching (sharp band)
3650 (s)
–
–
NH str.
Imidazolium
N
C
stretching
3730–3400 (s)
Bridged silanols, str.
Bridged silanols, str.
–
–
Si OH groups with strong hydrogen-bonding
interaction (broad band)
Molecular adsorbed water
3500–3400
3300–2700 (s)
H2O SiOH
–
H2O SiOH
–
CH and
CH2 str.
Aromatic and alkyl C H (a)symmetric
2969 (m)
2937–2882 (m)
1873 (w)
1662 (s)
–
–
OCH2 , asym. str.
CH2 str (asym. and sym.)
–
C
C
H asymmetric stretching
H (a)symmetric stretching
CH2 str (asym. and sym.)
Si
O
, str.
Si
O
, str.
Si
C
O
N, str.
, str.
Stretching, combination band
–
–
1632 (m)
1530 (s)
1451
OH (H2O)
OH (H2O)
SO2
OCH2 , str.
Si Si and Si
OH (H2O)
Bending OH, molecular water
Covalent sulfonate stretching
Asymmetric bending
–
–
O
O
SO2
–
1250–1000
Si
O
Si
O
C
Si
O
Si and Si
C
Asymmetric stretching mode
Fig. 10. TGA profiles for 25HF (a), covalently bonded RuCl(p-cymene)[(S,S)-Ts-
DPEN] (C) complex on functionalized 25HF (b), and [BMIM][BF4]-C/25HF-CSILP
catalyst (c).
bonds established between the aminopropyl functions and the
complex (Fig. 9A). The combined TG-DTA curves do not show well
defined steps in weight loss and both endo and exothermic peaks
are observed. The total mass loss was 27% corresponded to both
aminopropyl and complex entities but also to the dehydroxylation
of the support. Decomposition of the complex was completed at
600 ◦C.
Fig. 9. TG-DTA profiles for the covalently bonded RuCl(p-cymene)[(S,S)-Ts-DPEN]
(C) complex on MCM-41 (A) and for [BMIM][BF4]-C/MCM-41-CSILP catalyst (B).
The quantitative analysis of the MCM-41 CSILP-based sample
showed that the significant decomposition occurred. 45% of the
sample was lost in the 150–400 ◦C temperature range in well
defined steps (Fig. 9B). The shift of the onset decomposition tem-
perature for the CSILP catalyst (Fig. 9B), compared with that found
for the covalently bonded samples, may be attributed to the pres-
ence of the thin layer ionic liquid coverage onto the MCM-41
surface.
63.3% from the total amount of (3-aminopropyl)triethoxysilane
used during the functionalization process was grafted on the MCM-
41 surface.
The anchored RuCl(p-cymene)[(S,S)-Ts-DPEN] (C) complex
showed a different decomposition behavior due to the covalent
Different thermal behavior was observed in the case of 25HF
based samples (Fig. 10). Comparing the [BMIM][BF4]-C/MCM-41
sample (Fig. 9B) with the [BMIM][BF4]-C/25HF sample (Fig. 10c)
shows that, for the 25HF support, the decomposition of the ionic
liquid and of the chiral complex only started after 300 ◦C and the
weight loss took place in only one step (350–450 ◦C). Moreover, the
almost total loss in sample weight indicates complete decomposi-
tion of the support.
Table 4
The main features during the decomposition of the aminopropyl functions grafted
on the silica surface.
Step
Temperature, ◦
C
Mass loses, mg (%)
Enthalpy (ꢁH), J (J/g)
I
II
III
74–264
271–439
451–721
0.466 (2.54)
0.761 (4.12)
0.738 (3.99)
10.52 (570)
70.48 (3820)
2.05 (110.9)

70
I. Podolean et al. / Catalysis Today 200 (2013) 63–73
Table 5
Catalytic performances of MCM-41-based catalysts in hydrogenation of trimethylindolenine.
Complex
System
Catalyst type
Solvent
C, %
%e.e. (config.)
1
2
3
4
A
A
A
A
A
B
B
B
B
C
C
C
C
–
–
Homogeneous
Biphasic
CSILP
CSILP
CSILP
Homogeneous
Biphasic
CSILP
CSILP
Homogeneous
CSILP
CH2Cl2
[EMIM][NTf2]/hexane
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
[EMIM][NTf2]/hexane
CH2Cl2
CH2Cl2
CH2Cl2
77.0
67.0
34.5
11.6
6.0
71.2
40.0
85.0
42.6
13.4
9.6
23.0 (+)
29.3 (+)
44.8 (+)
51.2 (+)
12.0 (+)
44.6 (+)
47.8 (+)
49.7 (+)
25.0 (+)
70.1 (+)
86.8 (+)
59.3 (+)
80.2 (+)
[EMIM][NTf2]/MCM-41
[BMIM][BF4]/MCM-41
[BMIM][BF4]/MCM-41
–
5a
6b
7
–
8
[EMIM][NTf2]/MCM-41
[EMIM][NTf2]/MCM-41
–
[BMIM][BF4]/MCM-41
[BMIM][BF4]/MCM-41
Functionalized MCM-41
9a
10
11
CH2Cl2
CH2Cl2
CH2Cl2
12a
13
CSILP
Covalently bonded
4.5
7.0
Reaction conditions: All reactions had 100% chemo-selectivity to amine product. The data is compared at RT, 20 h, 30 bar H2, 250 mg of catalyst, S/C = 100. %e.e. was determined
from HPLC and the configuration was established by a comparison of the retention times with pure enantiomeric standards: tr(−) = 7.3 min, tr(+) = 8.4 min.
a
Recycled catalyst.
40 bar H2.
b
Table 6
Catalytic performances of porous carbon supported-catalysts in trimethylindolenine catalytic hydrogenation.
Complex
Carrier
Catalyst type
C%
e.e.%
1
2
3
4
5
6
A
A
A
A
A
B
B
B
B
B
B
–
Homogeneous
CSILP
CSILP
CSILP
CSILP
Homogeneous
CSILP
CSILP
CSILP
CSILP
77.0
59.0
48.0
62.9
55.0
71.2
4.0
nr
9.0
15.0
nr
23.0 (+)
25.7 (+)
41.2 (+)
38.0 (+)
22.0 (+)
44.6 (+)
98.5 (+)
nr
[EMIM][NTf2]/25HF
[BMIM][BF4]/25HF
[EMIM][NTf2]/4F5
[BMIM][BF4]/4F5
–
[EMIM][NTf2]/25HF
[EMIM][NTf2]/25HF
[EMIM][NTf2]/25HF
[EMIM][NTf2]/4F5
[EMIM][NTf2]/4F5
7
8a
9b
14.7 (+)
28.0 (+)
nr
10
11a
CSILP
Reaction conditions: All reactions had took place with a 100% chemo-selectivity to the amine product. The data is compared at RT, 20 h, 30 bar H2, solvent: CH2Cl2, 250 mg
of catalyst, S/C = 100. The e.e. determined from HPLC and configuration established by comparison of the retention times with pure enantiomeric standards: tr(−) = 7.3 min,
tr(+) = 8.4 min.
a
Recycled catalyst.
48 h.
b
parameters will be analyzed considering the same chemoselectiv-
ity and similar experimental conditions.
H2, catalyst
Higher conversions led to lower the product e.e.’s (Table 5,
S/C = 100/1
entries 1 and 2, for example). As expected, in comparison to hetero-
geneous systems, the homogeneous counterpart chiral complexes
led to higher conversions (Table 5, entries 1, 6 and 10). These con-
versions, however, greatly depended on the chiral complex used.
Table 5 shows that iridium is more active than ruthenium. The effect
of the ligand is less pronounced compared with the effect of the
metal but changes in the sterics of the ligand are not negligible.
For iridium, the combination of (COD)/BDPP (complex (A)) led to
slightly smaller conversions than BINAP (complex (B)) (entries 1, 2,
6, 7). The % e.e.’s were determined by the nature of chiral ligand.
The solvent also had a significant effect on the activity and
the selectivity of the reactions observed. Changing the monopha-
sic CH2Cl2 solvent with the biphasic [EMIM][NTf2]/hexane led to a
decrease in both the conversion and % e.e. (Table 5, entries 2 and 7).
This result can be explained by the partial solubility of the imine
ionic liquid but also to the encountered difficulties in separating
the product from the ionic liquid.
The immobilization of the complex A led to a further decrease
of the conversion compared with the homogeneous reaction but
did result in an enhanced e.e. (Table 5). Interestingly, the ionic
liquid is not a spectator in this process and the replacement of
[EMIM][NTf2] with [BMIM][BF4] led to an additional decrease of
the conversion (from 34.5% to 11.6%) that was accompanied by an
additional increase of e.e. (from 44.8% to 51.2%) (Table 5, entries 3
and 4). These differences may be associated to the differences in the
N
H
N
Scheme 4. The hydrogenation of trimethylindolenine.
3.2. Catalytic tests
3.2.1. C N hydrogenation
The catalytic results for the hydrogenation of trimethylindole-
nine (Scheme 4), in the presence of MCM-41 and carbon-supported
catalysts are summarized in Tables 5 and 6.
An interesting feature of the asymmetric catalytic synthesis is
the nonlinear correlation between the optical purity of the chiral
catalyst and that of the reaction product as reported for the first
time by Kagan et al. [53]. A strong amplification in the product chi-
rality may come at the expense of a severely suppressed rate of
product formation. Thus a system exhibiting a negative nonlinear
effect in the product e.e. can provide a significantly amplified rate
of formation of the desired product. In other words, there is a rela-
tionship between the reaction rate and enantioselectivity and, in
general, higher e.e.’s were reported at low conversions.
Data will be discussed in this chapter corresponds to similar
experimental conditions. Therefore, the selectivity will be not dis-
cussed considering results for the same conversion, but the both

I. Podolean et al. / Catalysis Today 200 (2013) 63–73
71
Cat. H2
N
CH3
N
CH3
Quinaldine
1,2,3,4-Tetrahydroquinaldine
Scheme 5. The hydrogenation of quinaldine to 1,2,3,4-tetrahydroquinaldine.
O
O
cat, H2
MeO
MeO
OMe
OMe
O
O
Scheme 6. The enantioselective hydrogenation of dimethylitaconate.
Fig. 11. TGA profiles for MCM-41 (a), fresh [BMIM][BF4]-C/MCM-41 catalyst (c), and
recycled [BMIM][BF4]-C/MCM-41 catalyst (b).
Another important factor influencing the stereoselectivity of the
reaction is the substrate structure. Replacing the trimethylindole-
nine substrate with a bulkier one, such as quinaldine, (Scheme 5)
led to a different behavior of the CSILP catalysts (Table 8). In com-
parison, for the homogeneous reaction conditions the differences
were not significantly different (Tables 5 and 8).
hydrogen concentration in the ionic liquid layer, which obviously
exerts a great effect on both conversion and e.e. [54]. An exception
to these general trends was shown by [IrCl(S)-BINAP]2 (B) complex.
Contrary to the results found for the other complexes, the immobi-
lization of B complex led to an increase in both conversion and e.e.
compared with the homogeneous system.
3.2.2. C C hydrogenation
On recycle of the CSILP catalyst a significant decrease in both
the conversion and e.e., irrespective of the nature of the catalyst,
was observed (Table 5, entries 5 and 12). This behavior provided a
clear indication on the fact that the chiral complex leached from the
support even during the first catalytic cycle. The leaching was also
confirmed by the TGA measurements (Fig. 11). Thus the importance
of the support is critical and a solvent must be utilized where the
chiral complex is less soluble than in the ionic liquid used.
Not only the nature of the chiral complex or of the ionic liquid
but also the nature of the support was found to greatly influence
the catalytic results (Table 6). Replacing the mesoporous siliceous
MCM-41 support with a highly porous carbon support led to a sig-
nificant change in behavior. A comparison of the catalytic activity
and e.e. for IrCl(COD)-BDPP (A) and [IrCl(S)-BINAP]2 (B) complexes
supported on 25HF and 4F5 carbons is shown in Table 6. The
[EMIM][NTf2]/25HF (Table 6, entry 7) led to a very high e.e. under
these conditions. However, the capacity of the carbon support to
retain these complexes was very small and strong deactivation was
observed on recycle (Table 6, entries 8 and 11). The elemental anal-
ysis confirmed the leaching of both chiral complex and IL phase
from the carrier surface during reaction (Table 7) irrespective of
the support (e.g., MCM-41 or highly porous carbon support). For
(C)-[BMIM][BF4]/MCM-41 (CSILP) sample (Table 7, entries 1 and 2)
the decrease of the sulfur content accounts for a leaching of the
chiral complex of around 21% that is also in accordance with the
catalytic results. The amount of nitrogen decreased with 55% in
respect to the initial amount. Taking into account that only a very
low amount of nitrogen originates from the chiral complex (where
N/S atomic ratio is of 2/1) it is clearly that not only the chiral com-
plex is lost during the reaction but also the IL. The leaching of IL
was also confirmed by the elemental analysis of the mesoporous
carbon-based sample (A)-[BMIM][BF4]/4F5 (CSILP), Table 7, entries
3 and 4) where the nitrogen originates only from IL. The elemental
analysis of the spent catalyst shows a lost of nitrogen of about 22%
compared to the initial content.
The hydrogenation of dimethylitaconate (Scheme 6) was per-
formed with Rh based complexes that are typical for catalysts
used in this type of reaction. [Rh(COD)(S,S)-[DIPAMP][BF4] (E)
and [Rh(COD)(R,R)-Me-DuPHOS][BF4] (F) chiral complexes were
selected for this purpose.
Table 9 presents the results using [Rh(COD)(S,S)-DIPAMP][BF4]
(E) under homogeneous conditions. The highest conversion and
e.e. were obtained at 50 ◦C and 5 bar H2. No reaction took place at
1 bar of hydrogen, irrespective of the reaction temperature (Table 9,
entries 1–3). At low temperatures (e.g., 25 ◦C) both the conversion
and e.e. increased with the hydrogen pressure (Table 9, entries
4 and 5) while at a higher temperature (e.g., 50 ◦C) both con-
version and e.e. was maximum (C = 99.8% and e.e. = 81.7%) at a
relatively low hydrogen pressure (e.g., 5 bar). Under these condi-
tions both the conversion and e.e. were maintained a very high
level (C = 98.1–100%, e.e. = 80.2–88.4%), irrespective of the solvent
used (Table 9, entries 6, 7 and 9). When compared with homo-
geneous systems using organic solvents (e.g., CH2Cl2 or Et2O),
slightly increased values were obtained working in biphasic ionic
liquid/organic solvent systems.
The CSILP catalyst was observed to be as active and enantiose-
lective as the homogeneous complex counterpart in Et2O solvent
(Table 9, entries 7 and 11). On comparison with the biphasic ionic
liquid/organic solvent system, CSILP catalyst displayed an even
higher activity while the e.e. was lower at around 10%. However,
the CSILP brings the advantages of heterogeneous catalysis coupled
with the usage of much lower amounts of ionic liquid.
The results obtained in the presence of the [Rh(COD)(R,R)-Me-
DuPHOS][BF4] (F) in hydrogen flow conditions are given in Table 10.
On recycle, as found for the hydrogenation of trimethylindole-
nine or 2-methylquinoline, a significant decrease in conversion was
observed due to leaching of the complex. However, in this case the
enantioselectivity was maintained at the high levels.
Working under a hydrogen flow led to better results. Using
the Me-Duphos ligand, the e.e. exceeded the values obtained
under homogeneous reaction conditions (Table 10, entry 1). How-
ever, the conversion did decrease on recycle again with the e.e.
maintained.
These results demonstrated once again that each modification
in the catalyst composition (complex, ligand, carrier, etc.) leads to
significant changes in the catalytic performance in terms of both
conversion and e.e.

72
I. Podolean et al. / Catalysis Today 200 (2013) 63–73
Table 7
Elemental analysis of the fresh and spent [BMIM][BF4]-C/MCM-41 catalysts.
Catalyst
N, %
C, %
H, %
S, %
Observation
(C)-[BMIM][BF4]/MCM-41 (CSILP)
(C)-[BMIM][BF4]/MCM-41 (CSILP)
(A)-[BMIM][BF4]/4F5 (CSILP)
(A)-[BMIM][BF4]/4F5 (CSILP)
4.9
2.7
3.1
2.4
20.2
19.8
72.8
68.4
3.1
2.2
2.0
1.2
0.12
0.095
–
Fresh catalyst
Spent catalyst
Fresh catalyst
Spent catalyst
–
Table 8
Catalytic performances of MCM-41-based catalysts in hydrogenation of quinaldine.
Complex
System
Catalyst type
Solvent/additive
C, %
e.e. (conf.), %
1
2a
3
4
5
6
7
8
9
A
A
A
A
A
C
C
C
C
C
E
E
–
–
–
–
Homogeneous
Homogeneous
Biphasic
Biphasic
CSILP
Homogeneous
Homogeneous
Homogeneous
CSILP
CSILP
Homogeneous
Biphasic
CH2Cl2
CH2Cl2
[EMIM][NTf2]/hexane
[BMIM][BF4]/hexane
CH2Cl2
71.0
89.6
28.7
3.0
19.6
51.2
67.2
73.7
43.0
12.0
94.3
14.5
31.4 (+)
7.4 (+)
18.0 (+)
35.5 (+)
19.3 (+)
44.6 (+)
65.3 (+)
99.8 (+)
56.0 (+)
16.2 (+)
99.2 (+)
85.3 (+)
[BMIM][BF4]/MCM-41
–
–
–
[BMIM][BF4]/MCM-41
[BMIM][BF4]/MCM-41
–
–
CH2Cl2
CH2Cl2/iPrOH HCOOH:TEA (5:2)
MeOH/iPrOH HCOOH:TEA (5:2)
CH2Cl2/iPrOH HCOOH:TEA (5:2)
CH2Cl2/iPrOH HCOOH:TEA (5:2)
MeOH
10b
11c
12
[BMIM][PF6]/hexane
Reaction conditions: All reactions had took place with a 100% chemo-selectivity to amine product. The data is compared at RT, 20 h, 30 bar H2, 250 mg of catalyst, S/C = 100.
The e.e. was determined from HPLC and configuration was established by comparison of the retention times with pure enantiomeric standards: tr(−) = 6.3 min, tr(+) = 6.9 min.
a
25 bar H2.
Recycled catalyst.
50 bar H2.
b
c
Table 9
Dimethylitaconate hydrogenation in the presence of the [Rh(COD)(S,S)-DIPAMP][BF4] (E) based catalytic systems.
Complex
Catalyst type
Reaction conditions
C, %
e.e., %
T, ◦
C
PH2 , bar
Solvent
1
2
3
4
5
6
7
8
9
E
E
E
E
E
E
E
E
Homogeneous
Homogeneous
Homogeneous
Homogeneous
Homogeneous
Homogeneous
Homogeneous
Homogeneous
Biphasic
25
50
50
25
25
50
50
50
50
50
50
50
1
1
1
25
45
5
5
25
5
5
5
CH2Cl2
CH2Cl2
Et2O
CH2Cl2
CH2Cl2
CH2Cl2
Et2O
CH2Cl2
[BMIM][BF4]/hexane
Et2O
n.d.
n.d.
n.d.
2.3
84.2
99.8
98.1
86.5
100
100
100
45.2
n.d.
n.d.
n.d.
45.9 (R)
73.2 (R)
81.7 (R)
80.2 (R)
75.7 (R)
88.4 (R)
53.8 (R)
78.3 (R)
29.3 (R)
E
10
11a
12b
E/MCM-41
E/MCM-41
E/MCM-41
Covalently bonded
CSILP
CSILP
Et2O
Et2O
5
S/C = 500.
a
CSILP: [Rh(COD)(S,S)-DIPAMP][BF4] (E) [BMIM][BF4]/MCM-41.
Recycled catalyst.
b
Table 10
Dimethylitaconate hydrogenation in the presence of the [Rh(COD)(R,R)-Me-DuPHOS][BF4] (F) based catalysts.
Complex
Catalyst type
Reaction conditions
C, %
e.e., %
T, ◦
C
PH2 , bar
Solvent
1
F
Homogeneous
Covalently bonded
CSILP
25
25
25
25
Flow
Flow
Flow
Flow
Et2O
Et2O
Et2O
Et2O
100
n.d.
22.5
7.5
91.0 (R)
n.d.
>99.9 (R)
>99.9 (R)
2
F/MCM-41
F/MCM-41
F/MCM-41
3a
4b
CSILP
a
[Rh(COD)(R,R)-Me-DuPHOS][BF4] (F)/[BMIM][BF4]/MCM-41.
Recycled catalyst.
b
4. Conclusions
these experiments. [EMIM][NTf2], [BMIM][BF4] and [BMIM][PF6]
were selected as ionic liquids. Comparative homogeneous and
heterogeneous experiments were carried out in asymmetric
Chiral supported ionic liquid phase (CSILP) catalysts were pre-
pared by physically or chemical bond immobilization of Ir, Ru
and Rh complexes on mesoporous MCM-41 and high porosity
carbons. IrCl(COD)-(S,S)-BDPP, [IrCl(S)-BINAP]2, RuCl(p-cymene)
[(S,S)-Ts-DPEN], RuOTf(p-cymene)[(S,S)-Ts-DPEN], [Rh(COD)(S,S)-
DIPAMP][BF4], and [Rh(COD)(R,R)-Me-DuPHOS][BF4] were used in
organometallic catalysis for the hydrogenation of double
C N
and bonds of trimethylindolenine, 2-methylquinoline
C
C
and dimethylitaconate, respectively. The conversions and enan-
tioselectivities were found to depend on the nature of the
complex (metal and ligand), the method by which the complex

I. Podolean et al. / Catalysis Today 200 (2013) 63–73
73
has been immobilized, nature of the ionic liquid, nature of
the support and experimental conditions. With the exception
of the [IrCl(S)-BINAP]2 (B) complex during the hydrogenation
of trimethylindolenine, in all other cases the CSILP cata-
lysts led to smaller conversions and e.e.’s compared with the
homogeneously catalyzed reactions. Very good conversions and
selectivities were also obtained in the hydrogenation of dimethyl-
itaconate with Rh complexes. Recycling experiments showed
that, irrespective of the solvent, leaching of the active species
occurred that led even in the first recycle to a decrease of the
conversion.
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