Biphasic hydroformylation of 1-octene catalyzed by cobalt complex of trisulfonated tris(biphenyl)phosphine

Article abstract of DOI:10.1016/j.apcata.2011.11.021

The aqueous biphasic hydroformylation of 1-octene catalyzed by cobalt complex of the water-soluble ligand trisulfonated tris(biphenyl)phosphine (BiphTS) was investigated in the absence and presence of various mass transfer promoters (co-solvents, surfactants, cyclodextrins and activated carbon). In the presence of cetyltrimethylammonium bromide, methylated β-cyclodextrin or activated carbon, the Co/BiphTS system allowed the hydroformylation of 1-octene with high conversion (92-95%) and aldehydes selectivity (85-90%). Moreover, the catalytic system could be easily reused in the presence of activated carbon as a mass-transfer promoter. In all cases, the conversion and the aldehydes selectivity were found to depend strongly on the ligand/cobalt ratio.

Full text of DOI:10.1016/j.apcata.2011.11.021

Applied Catalysis A: General 413–414 (2012) 273–279
Contents lists available at SciVerse ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Biphasic hydroformylation of 1-octene catalyzed by cobalt complex of
trisulfonated tris(biphenyl)phosphine
Aasif A. Dabbawala , Hari C. Bajaj , Hervé Bricout , Eric Monflierb
a
a,∗
b
a
Discipline of Inorganic Materials and Catalysis, Central Salt and Marine Chemicals Research Institute (CSIR – CSMCRI), Council of Scientific and Industrial Research (CSIR), G. B.
Marg, Bhavnagar 364 021,Gujarat, India
b
Université d’Artois, Unité de Catalyse et Chimie du Solide (UCCS), UMR CNRS 8181, Faculté des Sciences Jean Perrin, Rue Jean Souvraz, SP 18 - 62307 Lens Cedex, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 29 March 2011
Received in revised form 3 October 2011
Accepted 16 November 2011
Available online 26 November 2011
The aqueous biphasic hydroformylation of 1-octene catalyzed by cobalt complex of the water-soluble
ligand trisulfonated tris(biphenyl)phosphine (BiphTS) was investigated in the absence and presence
of various mass transfer promoters (co-solvents, surfactants, cyclodextrins and activated carbon). In
the presence of cetyltrimethylammonium bromide, methylated ␤-cyclodextrin or activated carbon, the
Co/BiphTS system allowed the hydroformylation of 1-octene with high conversion (92–95%) and alde-
hydes selectivity (85–90%). Moreover, the catalytic system could be easily reused in the presence of
activated carbon as a mass-transfer promoter. In all cases, the conversion and the aldehydes selectivity
were found to depend strongly on the ligand/cobalt ratio.
Keywords:
Aqueous biphasic catalysis
Hydroformylation
Higher olefin
©
2011 Elsevier B.V. All rights reserved.
Cobalt
Water-soluble phosphine
Activated carbon
1
. Introduction
rings [13,14]. However, the catalytic activities and chemioselectiv-
ities obtained with these ligands are different of those observed
with TPPTS [15].
Hydroformylation of olefins is an important industrial process
to produce aldehydes catalyzed by cobalt or rhodium based metal
complex [1–5]. The separation of the catalyst being dissolved in
the reaction medium becomes difficult with increasing molecular
weight of olefin. Among the different approaches to separate the
catalyst from the products [6], aqueous biphasic catalysis is of great
interest as it provides an easy separation of products and catalyst by
using water a benign solvent. Moreover, this strategy has proven its
commercial feasibility in the hydroformylation of propene devel-
oped by Ruhr Chemie–Rhone Poulenc [7–9]. In this approach, the
catalyst is effectively anchored in the aqueous phase by means of
thewatersolubleligands. Amongthevariouswater-solubleligands,
trisodium salt of tris(m-sulfophenyl) phosphine P(3-C H SO Na)
We have recently reported that the sodium salt of trisul-
fonated tris(biphenyl)phosphine (BiphTS) could advantageously
used instead of TPPTS [16]. BiphTS exhibits high solubility in
−
1
water (∼1.0 kg L ) and is much more accessible from a syn-
thetic point of view than TPPTS. Indeed, the sulfonation conditions
for BiphTS are much softer as concentrated H SO4 (98%) is used
2
instead of oleum 60%. Furthermore, this phosphine appeared
also to be a genuine water-soluble analogue of the organic
PPh3 as it displayed similar cone angle and basicity to PPh3.
Other important difference between BiphTS and TPPTS is that
the TPPTS is susceptible to oxidation. The yield of TPPTS is
lower in the tune of about 15–20% due to the formation of its
oxide during its synthesis while BiphTS is not easily oxidized
[16].
Herein, we report the application of BiphTS as a ligand in cobalt
catalyzed hydroformylation of 1-octene and describe influence of
various mass transfer additives on the conversion and selectiv-
ity. The development of an aqueous biphasic phosphine modified
cobalt hydroformylation technology is a great interest as the cobalt
catalysts are less expensive than rhodium catalysts and are able
to hydroformylate internal olefins selectively to linear aldehydes
[17–19].
6
4
3
3
(
TPPTS) is one the most commonly used ligand due to its excellent
coordinated ability and solubility in water [10–12]. The synthesis
of TPPTS is difficult because of the use of fuming sulfuric acid and
long reaction time (usually several days) which led to the formation
of phosphine oxide as impurity. The problem could be avoided by
introducing activating groups like methyl, methoxy on the phenyl
∗ Corresponding author. Tel.: +91 278 2471793; fax: +91 278 2566970.
E-mail address: hcbajaj@csmcri.org (H.C. Bajaj).
0
926-860X/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.apcata.2011.11.021

2
74
A.A. Dabbawala et al. / Applied Catalysis A: General 413–414 (2012) 273–279
2
. Experimental
were dissolved in n-hexane (12 g) and transferred into the cat-
alytic suspension. Then, hydroformylation reaction was performed
in autoclave reactor as per method describe above. After reaction,
the liquid and the solid were separated by filtration and finally,
organic phase was separated for GC analysis. For reusability of cat-
alyst, after filtration and decantation, the recovered aqueous phase
and recovered AC-WV were reloaded in autoclave with fresh 1-
octene, decane (internal standard), n-hexane (solvent) as described
above.
2
.1. General remarks
The sodium salt of trisulfonated tris(biphenyl)phosphine
(
BiphTS) was prepared according to a procedure previously
reported [16]. The purity of BiphTS was carefully controlled. In par-
ticular, 1H and P NMR analysis indicated that less than 1% of its
oxide was present. The syngas, CO/H2 (1:1) with purity of 99.9%
used was from Hydro Gas India Pvt. Ltd., India. 1-octene, CTAB, ␤-
cyclodextrin and RAME-␤-CD were purchased from M/s. Aldrich
Chemicals, USA. The CoCl ·6H O used in the reaction was pur-
31
2.4. Determination of cobalt contents in organic layer
2
2
chased from Merck, India. Distilled and deionised water was used
in all experiments.
To determine cobalt content in organic layer at the end of the
hydroformylation reaction, the organic layer was separated from
the aqueous layer and volatile compounds were removed under
reduce pressure. The organic layer was treated by aqua regia under
refluxing condition for overnight and then evaporated to dryness.
The distilled water was added into the remaining mass and filtered.
The cobalt contents in the aqueous solution were determined by
ICP-OES.
Water-soluble cobalt complex CoCl (BiphTS)2 was synthesized
2
following the procedure reported by Cotton et al. for the synthe-
sis of CoCl (PPh ) [20]. The commercial activated carbon Nuchar
WV-B denoted as AC-WV used as catalyst support was supplied by
MeadWestvaco Corporation, Covington, USA. It was produced from
wood and activated by a phosphorus acid. AC-WV has a large sur-
2
3 2
2
3
face area (1690 m /g), pore volume (1.32 cm /g), and average pore
size (3.1 nm).
3. Results and discussion
2.2. Instrumentation
3.1. Characterization
The hydroformylation reactions were performed in 100 mL
stainless steel autoclave (Autoclave Engineers, EZE-Seal Reactor,
The BiphTS ligand and CoCl (BiphTS)2 complex were charac-
terized by physicochemical techniques. The results of elemental
2
USA). 31P NMR spectra of ligand and metal complex were mea-
sured in D O using 85% H PO as an internal reference on Bruker
analyses were consistent with those calculated for CoCl (BiphTS)
2
3
4
2
2
31
Avance 500 MHz FT-NMR. IR spectra were recorded using nujol
mull and KBr pellet on PerkinElmer spectrum GX FT-IR system
complex, [Calc. (Found) %: C, 25.07 (25.65); H, 1.39 (1.57)].
P
NMR spectrum of CoCl (BiphTS)2 complex gave a broad singlet at
2
−1
−1
in the range 4000–400 cm
with a resolution of 4 cm . The
53.5 ppm (may be due to the paramagnetic nature of the complex
or equilibrium between Co species and free phosphine in solution)
indicating the equivalence of two phosphorous atoms of BiphTS.
UV–vis spectra were recorded on UV–vis spectrophotometer (Shi-
madzu UV-3101PC) at room temperature in the wavelength range
of 200–800 nm. Elemental analyses were done on PerkinElmer,
−
1
IR spectrum of CoCl (BiphTS) complex gave bands at 1191 cm
2
−1
2
−
−1
ꢀ
2
400 C, H, N, S and O analyzer. X-ray photoelectron spectroscopy
for ꢁSO3 , 1125 cm for ꢁSO, 638 cm for ꢁ SO, 1481, 1385, 815
−
1
(
XPS) was performed using a Multilab-2000 (Thermo-scientific UK)
and 715 cm
for ꢁph. The coordination of ligand and nature of
spectrometer. MALDI-TOF mass spectra were acquired using Ultra-
flex TOF/TOF, Bruker Daltonics Germany which is equipped with
a nitrogen laser (ꢀ = 337 nm). Products were analyzed on a Shi-
madzu GC-17A gas chromatograph (GC) using flame ionization
detector (FID) having 5% diphenyl- and 95% dimethyl siloxane capil-
lary column (60 m length, 0.25 mm diameter). Column temperature
coordinated BiphTS ligand in CoCl (BiphTS)2 were also probed by
UV–vis spectroscopy comparing the UV–vis spectrum of a free lig-
2
and with that of CoCl (BiphTS) complex. The UV–vis spectrums of
2
2
CoCl ·6H O, BiphTS ligand and CoCl (BiphTS) complex in H O are
2
2
2
2
2
presented in Fig. 1.
A UV–vis spectrum of a free BiphTS ligand exhibited one high
intense absorption band at 271 nm whereas no band appeared at
higher wavelengths. This is reasonable accordance with literature
of PPh3 (at 260 nm) [21]. A UV–vis spectrum of CoCl ·6H O dis-
◦
◦
was initially kept at 50 C for 5 min and then raised to 200 C at
◦
1
0 C/min. n-decane was used as internal standard and the GC was
also calibrated using known amount of corresponding aldehydes.
2
2
played two weak absorption bands at 512 and 545 nm. The cobalt
complex, CoCl (BiphTS) revealed a intense broad absorption band
2.3. General procedure for hydroformylation
2
2
at 281 nm and other two weak bands at higher wavelength of
503 and 551 nm (Fig. 1). The similar three absorption bands
were observed for CoCl (PPh ) complex [20,22]. The shift and
In the case of surfactant and cyclodextrins, a typical hydro-
formylation experiment was conducted as follow: a required
amount of cobalt catalyst, ligand, surfactant/cyclodextrins, sub-
strate (1-octene) and solvent were charged into the reactor. The
reactor was flushed three times with nitrogen followed by flush-
ing with syngas twice at room temperature. Then, the reactor was
brought to desire reaction temperature and pressurized with syn-
gas. The reaction was initiated by stirring (1000 rpm). After preset
reaction time, the stirring was stopped, reactor was cooled down
to room temperature, depressurized, flushed with N2 and opened
to collect final sample for a GC analysis.
2
3 2
broadening of absorption band at 281 nm in the UV–vis spec-
trum of CoCl (BiphTS) indicates a dynamic ligand exchange in the
2
2
complex and characteristic of pseudo-tetrahedral Co(II) complex
[20,22].
Based on the literature data [23–25] and experimental study, a
reaction scheme is proposed for the formation of active catalytic
I
II
species HCo (CO) (BiphTS) from Co Cl (BiphTS) (Scheme 1). The
3
2
2
carbon monoxide reacts with cobalt complex, CoCl (BiphTS)2 to
2
give a five coordinated complex, Co(CO)(BiphTS) Cl2 (1) and then
2
In the case of activated carbon AC-WV, a typical hydroformy-
lation experiment was conducted as follow: a required amount
of cobalt catalyst, ligand, AC-WV and water were charged into
the reactor and the resulting catalytic suspension was stirred at
room temperature under 5.0 MPa syngas pressure for 12 h. Then, 1-
octene (17.82 mmol), decane (200 mg; used as an internal standard)
six coordinated cobalt carbonyl complexes Co(CO) (BiphTS) Cl
2
2
2
(2), which are in equilibrium. The six coordinated com-
plex, Co(CO) (BiphTS) Cl (2) can react with five coordinated
2
2
2
cobalt intermediate (1) by redox bridging mechanism to give
I
III
Co (CO) (BiphTS) Cl (3) species and unstable Co (CO)(BiphTS) Cl3
2
2
2
(4) complex [25]. The formation of similar five, six coordinated

A.A. Dabbawala et al. / Applied Catalysis A: General 413–414 (2012) 273–279
275
Fig. 1. UV–vis spectrums of CoCl2·6H2O, CoCl2(BiphTS)2 and BiphTS.
−
with the reported IR peak for HCo(CO) (TPPTS) at 2089 cm
3
1
cobalt carbonyl species and Co(I) carbonyl complex with PPh3
have been reported by Bressan et al. [25] by the interaction of
CoCl (PPh ) with CO. In order to ascertain the formation of
[3]. The aqueous solution on evaporated in vacuo gave IR
−
1
−1
(Fig. 2d), that could be
2
3 2
peak at 2000 cm
due to the mixture of Co(CO) (BiphTS)2 or Co (CO) (BiphTS)
2
and 1951 cm
such cobalt carbonyl complexes in the case of CoCl (BiphTS) ,
2
2
3
2
6
◦
one experiment was conducted under CO (4 MPa) at 100 C with
CoCl (BiphTS) in water. After 3 h, the resulting solution was evap-
as hydrido cobalt carbonyl species is stable only syngas envi-
ronment and attempts to isolate yielded mixture of cobalt
carbonyl complexes [27]. The MALDI-TOF–MS analysis of result-
ing compound obtained by evaporating the aqueous phase
2
2
orated in vacuo to give solid. The infrared spectra of solid so
−
1
obtained displayed a band at 1920 cm
and a shoulder in the
−1
region of 2010–2020 cm (Fig. 2b) which confirms the formation
of Co(CO) (BiphTS) Cl (2) and/or Co (CO) (BiphTS) Cl (3).
after reaction of CoCl (BiphTS)2 with syngas also confirmed the
2
I
2
2
2
2
2
formation of such cobalt carbonyl complexes (see Supporting
information).
In order to confirm the possible oxidation states of Co ion
the XPS analysis of Co/BiphTS complexes was carried out. The
Indeed, these values are in reasonable accordance with lit-
−
1
erature values of Co(CO) (PPh ) Cl at 1919 and 1984 cm [26].
2
3 2
The reaction of (3) with H2 gives HCo(CO) (BiphTS)2 (5). Finally
2
HCo(CO) (BiphTS)2 reacts with CO and with the dissociation of
high resolution Co 2p XPS spectra of CoCl (BiphTS) and result-
ing compound, Co (CO) (BiphTS) abbreviated as CoCOBT obtained
x y
2
2 2
I
ligand BiphTS, gives active catalytic species HCo(CO) (BiphTS)
3
(
6). In order to confirm the formation of such active hydrido
by evaporating the aqueous phase after reaction of CoCl (BiphTS)
with syngas (8 MPa,100 C) are presented in Fig. 3. The Co 2p region
2 2
◦
cobalt carbonyl species HCo(CO) (BiphTS) by interaction of syn-
3
gas with CoCl (BiphTS) , another experiment was carried out
of CoCl (BiphTS)2 exhibited four peaks; two main peaks due to Co
2
2
2
◦
with CoCl (BiphTS)2 in water under syngas (8 MPa) at 100 C.
2p(3/2), Co 2p(1/2) and the shake up resonance transitions (satel-
lites) of these two peaks above the 2p(3/2) transition (Fig. 3a).
The Co 2p(3/2) and Co 2p(1/2) binding energies obtained as 782.6
2
After 6 h, the IR spectra of the resulting aqueous solution gave
−1
a
broad and strong peak at 2090 cm
(Fig. 2c) analogous
Scheme 1. Interaction of CoCl2(BiphTS)2 with syngas.

2
76
A.A. Dabbawala et al. / Applied Catalysis A: General 413–414 (2012) 273–279
The catalytic performance of water-soluble ligand, BiphTS was
then evaluated in cobalt catalyzed hydroformylation of 1-octene in
the absence and presence of various mass transfer promoters. Reac-
tion products were nonanal (linear aldehyde) and 2-methyl octanal
6
5
4
3
2
1
0
0
0
0
0
0
d
c
(branched aldehyde) represented as linear to branched aldehyde
ratio (l/b). Side products were internal octenes (2-octene, 3-octene)
and octane resulted from 1-octene isomerization and hydrogena-
tion. As the selectivity of products in hydroformylation reaction
mainly depends on the parameters such as temperature, syngas
pressure, ligand/Co ratio, the hydroformylation experiments were
carried out by varying these parameters.
b
a
3.2. Co/BiphTS catalyzed hydroformylation of 1-octene in the
absence of mass transfer promoters
In the absence of any mass transfer promoters, the hydroformy-
lation of 1-octene catalyzed by the Co/BiphTS system showed low
activity due to the poor solubility of 1-octene in water. Effect of
temperature and syngas pressure on conversion and selectivity was
studied for determining the optimum condition. The results are
summarized in Table 1.
4
000
3500
3000
2500
2000
1500
1000
500
-1
Wave number (cm )
Fig. 2. FT-IR spectra of CoCl2(BiphTS)2 and cobalt carbonyl intermediate species.
a) IR spectrum of CoCl2(BiphTS)2; (b) IR spectrum of the compound after reaction
of CoCl2(BiphTS)2 with CO; (c) IR spectrum of the aqueous phase after reaction of
CoCl2(BiphTS)2 with syngas; (d) IR spectrum of the resulting compound obtained
by evaporating the aqueous phase after reaction of CoCl2(BiphTS)2 with syngas.
(
◦
Temperature was varied from 90 to 130 C at constant syngas
pressure (8.0 MPa). With an increase in temperature, the conver-
sion and isomerization of 1-octene increased (Table 1). However,
aldehydes chemoselectivity and l/b aldehyde ratio were found to
decrease with an increase in temperature. The decrease in aldehy-
des selectivity at higher temperature is mainly due to the increase
in the isomerization products. Indeed, it is well known that internal
alkenes are more difficult to hydroformylate than terminal alkenes
and 798.6 eV respectively. These binding energies are very close to
those reported for Co ions [28]. Comparison of XPS data of Co
p in CoCl (BiphTS) with that of CoCOBT indicate that the bind-
ing energies (BE) of Co 2p(1/2) and Co 2p(3/2) in CoCOBT complex
shifted from 798.6 to 797.3 eV and 782.6 to 781.4 eV respectively.
+2
2
2
2
[
17]. The best agreement between conversion and aldehyde selec-
◦
+
tivity was achieved at 120 C. The hydroformylation of 1-octene
catalyzed by Co/BiphTS system was then studied at 120 C under
The known complex of Co(I) [Co(CO) (PPh ) ] exhibits the Co
p(3/2) peak at 781.9 eV [28]. Similarly the complex CoCOBT dis-
3
3 2
◦
2
different syngas pressure (Table 1). The total syngas pressure was
found to affect the conversion and aldehyde selectivity. The results
indicated that the hydroformylation of 1-octene proceed slowly
at low syngas pressure. The conversion and aldehyde selectivity
were increased with an increase in the syngas pressure whereas
the isomerization decreased gradually with increase in the syngas
pressure.
As TPPTS is a benchmark ligand in aqueous organometallic catal-
ysis, the catalytic activity of the Co/BiphTS system was compared
with the catalytic activity of Co/TPPTS system. The Co/BiphTS sys-
tem was slightly less active and selective than the Co/TPPTS system
played Co 2p(3/2) peak at 781.4 eV (Fig. 3b) confirming that the
cobalt carbonyl complex CoCOBT is also a Co(I) compound. In addi-
tion, the presence and absence of the satellites peaks in XPS analysis
clearly distinguish between Co(II) and Co(I) species, because the
main Co(II) depict satellites (shake-up peaks) whereas the Co(I)
do not [28]. As shown in Fig. 3a, in CoCl (BiphTS) , the Co 2p(3/2)
2
2
peak is accompanied by the intense shake-up signals on the high
binding-energy characteristic of Co(II) while in CoCOBT only a weak
shake-up single supplement with 2p(3/2) peak was observed.
(Table 1, compare entry 8 with 2). This can be explained by the
fact that BiphTS is comparatively more basic than TPPTS. Indeed,
BiphTS can bind more strongly to cobalt than TPPTS leading to a
781.4
lower concentration of catalytically active species HCo(CO) L.
3
The effect of BiphTS/Catalyst ratio on the conversion and selec-
◦
tivity of 1-octene hydroformylation was studied at 120 C and
8
.0 MPa by varying ligand/Catalyst ratio (Table 2). An increase in
782.6
the BiphTS/Catalyst ratio had noticeable effect on the conversion
and the selectivity. The conversion of 1-octene decreased from 36
to 12%. However, aldehyde selectivity and l/b aldehyde ratio were
increased from 45 to 48% and 2.3 to 2.5, respectively. The leach-
ing of cobalt from aqueous phase to the organic phase decreased
from 1.6 to 0.05 ppm with an increase in BiphTS concentration
b
a
(Table 2). These results can be rationalized by considering the
equilibrium between the species HCo(CO)2L2 (5) and the catalytic
active species HCo(CO) L (6). As BiphTS is comparatively more basic
3
than TPPTS, the equilibrium between HCo(CO)2L2 and HCo(CO)3L
is likely shifted towards the less active HCo(CO) L species in pres-
2
2
8
05
800
795
790
785
780
775
770
ence of excess ligand. It is also notice that effect of BiphTS/Co ratio
on the conversion and selectivity is much more pronounced than in
the case of the TPPTS (Table 2) [3]. These results also confirm that
the BiphTS ligand coordinates more strongly to Co catalyst than
TPPTS. Although the reaction can also occur in the organic phase
Binding energy (eV)
Fig. 3. The high resolution Co 2p XPS spectra of CoCl2(BiphTS)2 (a) and result-
ing compound (b) obtained by evaporating the aqueous phase after reaction of
CoCl2(BiphTS)2 with syngas.

A.A. Dabbawala et al. / Applied Catalysis A: General 413–414 (2012) 273–279
277
Table 1
a
Effect of temperature and pressure on hydroformylation of 1-octene catalyzed by CoCl2(BiphTS)2 in aqueous medium.
◦
Entry
Temp. ( C)
Press. (MPa)
Conv. (%)
Salkane (%)
Sisomer (%)
Saldehyde (%)
l/b
1
2
3
4
5
6
7
90
100
110
120
130
120
120
100
8
8
8
8
8
9
7
8
12
23
31
36
45
38
34
29
–
2
6
31
38
45
47
58
42
53
26
69
60
49
45
30
48
27
65
2.6
2.5
2.3
2.3
2.1
2.2
2.2
2.8
8
12
10
20
9
b
8
a
Reaction conditions: 1-octene = 17.82 mmol, [CoCl2(BiphTS)2] = 0.48 mM, decane = 200 mg, solvent (water) = 25 mL, reaction time = 5 h.
CoCl2(TPPTS)2 was used instead of CoCl2(BiphTS)2.
b
Table 2
a
Effect of BiphTS concentration on hydroformylation of 1-octene catalyzed by CoCl2(BiphTS)2 catalyst.
Entry
Add. BiphTS/Cat.
Conv. (%)
Salkane (%)
Sisomer (%)
Saldehyde (%)
l/b
Co leaching (ppm)
1
2
3
4
–
36
27
20
12
8
7
8
7
47
47
46
45
45
46
46
48
2.3
2.3
2.4
2.5
1.6
1.1
0.6
0.05
2:1
4:1
6:1
a
◦
Reaction conditions: 1-octene = 17.82 mmol, [CoCl2(BiphTS)2] = 0.48 mM, Temp. = 120 C, Press. = 8 MPa, decane = 200 mg, solvent (water) = 25 mL, reaction time = 5 h.
due to the presence of water insoluble hydrido species HCo(CO)x
x: 3,4) under CO/H2 pressure and high temperature, the ICP-OES
2–4) and 10 mM RAME ␤-CD concentration (Table 5, entries 2–4).
When BiphTS concentration increased, the 1-octene conversion
and aldehyde selectivity were remarkably decreased in both cases.
In the case of CTAB, the conversion of 1-octene and the aldehydes
selectivity decreased from 95 to 60% and from 86 to 68%, respec-
tively. While in the case of RAME-␤-CD, the 1-octene conversion
decreased from 95 to 51% with the decreasing in the aldehyde
selectivity from 85 to 65%. On the other hand, it was observed
that separation time of aqueous and organic phases after end of
the reaction decreased with an increasing in BiphTS concentration
in the case of CTAB. Compared to Co/TPPTS system, the addition of
excess BiphTS ligand decreases conspicuously the conversion and
aldehyde selectivity [3,19]. These results are in agreement with
those obtained without mass transfer additives and confirm that
the BiphTS ligand coordinates more strongly to Co species than
TPPTS. In order to increase the 1-octene conversion and aldehyde
selectivity, we also combined co-solvent with CTAB and increased
syngas pressure (9.0 MPa). The conversion was increased (60–75%)
with aldehyde chemoselectivity increased from 68 to 78% (Table 4,
entry 5). Whereas the concentration of RAME-␤-CD increased from
(
analyses demonstrate that the catalytic system is immobilized into
the aqueous phase when the reaction mixture is cooled and depres-
surized to ambient conditions. Indeed, the amount of cobalt in the
organic phase at the end of the reaction was very low and decreased
notably when the phosphine/cobalt ratio increased (Table 2).
3.3. Co/BiphTS catalyzed 1-octene hydroformylation in the
presence of mass transfer promoters
In order to improve the solubility of 1-octene in aqueous media,
co-solvents, surfactants and modified cyclodextrins have been
used. In the presence of co-solvents (methanol and ethanol), 1-
octene conversion was increased up to 58 and 56% with aldehyde
selectivity to 54 and 55% in methanol and ethanol respectively
(
Table 3, entries 1 and 2). In the case of native ␤-cyclodextrin, the
conversion was increased up to 66% with 50% aldehyde chemose-
lectivity (Table 3, entry 6). The cetyltrimethylammonium bromide
(
CTAB) and randomly methylated ␤-cyclodextrin (RAME-␤-CD)
1
0 mmol to 40 mmol/L, the conversion was increased (51–62%)
greatly enhanced the conversion and the aldehyde selectivity.
Thus, high conversion (95%) with 85–86% aldehyde selectivity was
obtained in the case of CTAB and RAME-␤-CD. However, the l/b
aldehyde ratio dropped from 2.3 to 1.3 while using RAME-␤-CD.
The beneficial effect of such additives on the mass transfer is well
documented in the literature and has been attributed to the for-
mation of micelles and inclusion complexes between the substrate
and the cyclodextrin [29–34]. For example, the CTAB form cationic
micelle which augment the anionic catalytic species on the surface
of micelles through the static attraction and dissolved the olefin in
the inner micelle to increase the coordination of olefin with cat-
with aldehyde chemoselectivity increased from 65 to 70% (Table 5,
entry 5).
Recently, the possibility of using an activated carbon as a mass
transfer additive in aqueous organometallic catalysis has been
NaO3S
−
alytic species. The TPPTS and BiphTS both have anionic SO3 group
SO3Na
(
Fig. 4). The addition of mass transfer additives increased the con-
version and aldehyde selectivity in the case of Co/BiphTS too. This
clearly evident that role of mass-transfer agents is same in the both
TPPTS and BiphTS ligands. As expected, a decrease in the concen-
tration of CTAB and RAME ␤-CD led to lower activities. In the case
of RAME-␤-CD, the formation of an emulsion at the end of reaction
was not observed and separation of the aqueous and organic phase
was rapid.
The effect of BiphTS concentration in presence of CTAB and
RAME-␤-CD was also investigated. The BiphTS/Catalyst ratio was
varied from 2 to 6 at constant 5.5 mM CTAB (Table 4, entries
P
3
SO Na
SO3Na
P
NaO S
3
TPPTS
NaO3S
BIPhTS
Fig. 4. Structure of trisodium salt of tris(m-sulfophenyl) phosphine (TPPTS) and
trisodium salt of trisulfonated tris(biphenyl)phosphine (BiphTS).

2
78
A.A. Dabbawala et al. / Applied Catalysis A: General 413–414 (2012) 273–279
Table 3
Effect of co-solvents, surfactants and cyclodextrins on hydroformylation of 1-octene catalyzed by CoCl2(BiphTS)2.
a
Entry
Co-solvent
Mass transfer additive (mmol/L)
Conv. (%)
Salkane (%)
Sisomer (%)
Saldehyde (%)
l/b
1
2
3
4
5
6
7
8
Methanol
Ethanol
–
–
58
56
79
85
95
66
90
95
6
6
5
6
4
7
5
5
40
39
12
11
10
43
14
10
54
55
83
83
86
50
81
85
2.1
2.1
2.2
2.1
2.1
1.5
1.3
1.3
–
–
–
–
–
–
CTAB (2.5)
CTAB (4.5)
CTAB (5.5)
␤-CD (15)
RAME-␤-CD (5)
RAME-␤-CD (10)
a
◦
Reaction conditions: 1-octene = 17.82 mmol, [CoCl2(BiphTS)2] = 0.48 mM, Temp. = 120 C, Syngas pressure = 8.0 MPa, decane = 200 mg, co-solvent = 5 mL, solvent
water) = 20 mL, reaction time = 5 h.
(
Table 4
a
Effect of BiphTS concentration in presence of CTAB on hydroformylation of 1-octene catalyzed by CoCl2(BiphTS)2 catalyst.
Entry
Add. BiphTS/Cat.
Time (h)
Conv. (%)
Salkane (%)
Sisomer (%)
Saldehyde (%)
l/b
Org/aqua.
Phase separation time
(
min)
1
2
3
4
–
5
5
9
9
9
95
75
65
60
75
4
6
5
5
5
10
33
31
27
17
86
61
64
68
78
2.1
60
15
05
05
05
2:1
4:1
6:1
6:1
2.1
2.2
2.3
2.2
b
5
a
◦
Reaction conditions: 1-octene = 17.82 mmol, [CoCl2(BiphTS)2] = 0.48 mM, Temp. = 120 C, Syngas pressure = 8.0 MPa, CTAB = 5.5 mmol/L, decane = 200 mg, solvent
water) = 25 mL.
Co-solvent (methanol) = 5 mL, [CTAB] = 6.0 mmol/L, Press. = 9.0 MPa.
(
b
Table 5
a
Effect of BiphTS concentration in presence of RAME-␤-CD on hydroformylation of 1-octene catalyzed by CoCl2(BiphTS)2 catalyst.
Entry
Add. BiphTS/Cat.
Time (h)
Conv. (%)
Salkane (%)
Sisomer (%)
Saldehyde (%)
l/b
1
2
3
4
–
5
5
10
10
10
95
71
60
51
62
5
6
5
5
5
10
46
34
30
25
85
58
61
65
70
1.3
1.3
1.4
1.5
1.5
2:1
4:1
6:1
6:1
b
5
a
◦
Reaction conditions: 1-octene = 17.82 mmol, [CoCl2(BiphTS)2] = 0.48 mM, Temp. = 120 C, Press. = 8 MPa, [RAME-␤-CD] = 10 mmol/L, decane = 200 mg, solvent
(
water) = 25 mL.
b
[RAME-␤-CD] = 40 mmol/L.
Table 6
a
Hydroformylation of 1-octene catalyzed by CoCl2(BiphTS)2 in presence of AC-WV.
Entry
1b
Add. BiphTS/Cat
Conv. (%)
Salkane (%)
Sisomer (%)
Saldehyde (%)
l/b
–
–
–
4
4
2
2
2
2
2
53
56
82
51
85
92
96
92
92
88
2
2
7
2
2
–
–
–
–
–
23
22
30
30
32
10
08
12
14
15
75
76
63
68
75
90
93
88
86
85
1.5
1.5
1.3
1.6
1.5
1.3
1.3
1.3
1.2
1.2
b,c
2
3
4
5
6
7
d
d
e
1
2
3
st recycled
d
nd recycle
rd recycled
a
◦
Reaction conditions: 1-octene = 17.82 mmol, [CoCl2(BiphTS)2] = 0.6 mM, AC-WV = 50 mg, Temp. = 120 C, Press. = 9 MPa, decane = 200 mg, water = 20 mL, n-hexane = 12 g,
reaction time = 6 h.
b
◦
Temp. = 90 C.
c
AC-WV = 75 mg.
Reaction time = 10 h.
Reaction performed with CoCl2(TPPTS)2.
d
e
reported [35]. The beneficial effect of activated carbon on the mass
transfer was attributed to an increase in the interfacial area and to
a confinement of catalyst and reactants in pores [35–37]. Thus, the
mass transfer efficiency of activated carbon in hydroformylation
of 1-octene under biphasic conditions was investigated by adding
activated carbon AC-WV into catalytic solution. The results are
summarized in Table 6. In order to explore precisely the influence
of activated carbon AC-WV under different operating parame-
ters such as effect of temperature, effect of BiphTS concentration,
reaction time and amount of AC-WV, few control experiments were
performed by varying such parameters under constant syngas pres-
sure (9 MPa) with 50 mg of AC-WV. At 90 C, the conversion of
◦
1-octene is low (53%) which increased up to 82% with 63% aldehyde
◦
selectivity in 6 h at 120 C (Table 6, entries 1 and 3). Surprisingly,
the conversion of 1-octene was not greatly affected by additional
(25 mg) activated carbon (Table 6, entry 2). This result indicates
that 50 mg of AC-WV is sufficient to act as mass transfer promoter
in present reaction system. The conversion of 1-octene noticeably

A.A. Dabbawala et al. / Applied Catalysis A: General 413–414 (2012) 273–279
279
decreased from 82 to 51% with an increase in the ligand/Catalyst
up to 4 (Table 6, entries 3 and 4). However, the conversion and
aldehyde selectivity increased significantly when reaction time
increased up to 10 h (Table 6, entry 5). Interestingly, the conver-
sion and the aldehydes selectivity reached maximum, i.e. 92 and
Network Project. AAD thanks CSIR, New Delhi, for the award of
Senior Research Fellowship. Authors are also thankful to Dr. M.
Jayachandran, Electrochemical Materials Science Division, Central
Electrochemical Research Institute (CSIR), Karaikudi, India for XPS
analysis.
9
0%, respectively at low ligand/Catalyst ratio of 2 in 10 h (Table 6,
entry 6). In order to compare the catalytic activity of the Co/BiphTS
system with Co/TPPTS system, one experiment was carried out with
catalyst CoCl (TPPTS) under similar reaction condition (Temp.
Appendix A. Supplementary data
2
2
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.apcata.2011.11.021.
◦
1
1
9
20 C, 9 MPa syngas pressure, ligand/Catalyst = 2 and reaction time
0 h). In this case, the conversion of 1-octene was found 96% with
3% aldehyde selectivity. From the result of CoCl (TPPTS) , one can
2
2
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