Modification of rhodium catalyst with stibines for hydroformylation of 1-pentene

Article abstract of DOI:10.1002/jccs.200700097

Homogeneous hydroformylation of 1-pentene under synthesis gas experimental conditions was studied using RhClCO(PPh₃)₂ complex with different triarylstibines. Three different stibine ligands SbR₃ [where R = 2,4,6-mesityl (TMS), 2-furyl (TFS), 2-N,N-dimethylbenzylamine (TDMBAS)], have been tested. It is interesting to note that 2:1 addition of these stibine ligands to the RhClCO(PPh₃)₂ complex catalyst increases the aldehydes yields with an appreciable n:iso ratio. The catalytic activity of the system shows a TDMBAS > TMS > TFS pattern which indicates that not only basicity of the ligand alone is playing a role in the activity but the steric effect is also very important, and it is combination of these two factors that contributes to the resulting catalytical activity. The maximum yield of aldehydes obtained were 98.7% with n/iso = 1.4 when RhClCO(PPh₃)₂ + TFS system was used and 93.7% with n/iso = 2.43 when TDMBAS ligand was studied.

Full text of DOI:10.1002/jccs.200700097

Journal of the Chinese Chemical Society, 2007, 54, 681-684
681
Modification of Rhodium Catalyst with Stibines for Hydroformylation of
1
-Pentene
a
b
a
a
Pankaj Sharma, * Jose Luis Arias, * Jaime Vasquez, Valente Gomez and Rene Guiterrez
c
a
Instituto de Química, UNAM, Circuito Exterior, Coyoacán, D.F. 04510, México
b
Facultad de Estudios Superiores Cuautitlán, UNAM, Cuautitlán Izcalli, Estado de 54700, México
c
Facultad de Ciencias Quòmicas, U.A.P., Puebla 72001, México
Homogeneous hydroformylation of 1-pentene under synthesis gas experimental conditions was stud-
ied using RhClCO(PPh complex with different triarylstibines. Three different stibine ligands SbR
where R = 2,4,6-mesityl (TMS), 2-furyl (TFS), 2-N,N-dimethylbenzylamine (TDMBAS)], have been
tested. It is interesting to note that 2:1 addition of these stibine ligands to the RhClCO(PPh complex cat-
3
)
2
3
[
3 2
)
alyst increases the aldehydes yields with an appreciable n:iso ratio. The catalytic activity of the system
shows a TDMBAS > TMS > TFS pattern which indicates that not only basicity of the ligand alone is play-
ing a role in the activity but the steric effect is also very important, and it is combination of these two fac-
tors that contributes to the resulting catalytical activity. The maximum yield of aldehydes obtained were
98.7% with n/iso = 1.4 when RhClCO(PPh
TDMBAS ligand was studied.
3 2
) + TFS system was used and 93.7% with n/iso = 2.43 when
Keywords: Stibines; Hydroformylation; Rhodium catalyst.
INTRODUCTION
There exist a number of reports on modification of
2-N,N-dimethylbenzylamine) were prepared according to
9
the literature.
-11
1
,2
rhodium catalyst by different phosphines ligands; how-
Measurements
The reaction products were analyzed on JEOL JMS-
ever, there are a few reports on the modification of these
4
,5
catalysts with stibine ligands. Recently our group has re-
ported the modification of Rh and Co catalysts by different
arylstibines for hydroformylation and amidocarbonylation
AX505 HA GC-MS equipment with a 25 m ´ 10.3 mm
glass column packed with 5% phenylsilicone and com-
pared with pure Aldrich samples, quantified by GC using
hexane as an internal standard (added after the reaction and
just before analyzation) in a Hewlett Packard 5890 ana-
lyzer with a 20 m ´ 0.2 mm glass column packed with
Carbowax 20 M. The IR spectra were obtained by using a
Nicolet FTIR Magna 750 spectrometer.
6
-8
reactions. In view of the scanty reports on the modifica-
tion of Rh with antimony ligands in hydroformylation reac-
tions, this work was undertaken. This paper presents the
3 2
modification of rhodium catalyst viz. RhClCO(PPh ) with
different stibines in the hydroformylation of 1-pentene.
General Catalytic Procedure
-
In a Schlenck tube, 9.143 ´ 10 mol of catalyst
5
MATERIALS
-
4
[
RhCOCl(PPh
3 3
) ] and 2 ´ 10 mol of ligand (1:2 molar ra-
All the solvents used were purified, dried and de-
tio) were dissolved in 5 mL of benzene. This mixture was
-
3
oxygenated. RhCOCl(PPh
Chemicals Company. 1-Pentene, SbCl
Aldrich. CO, H were obtained from Matheson and Aga
Gas Inc., respectively, and used without further purifica-
tion. The ligands SbR (where R = 2,4,6-mesityl, 2-furyl,
3
)
2
was purchased from Strem
stirred for three minutes and 9.143 ´ 10 mol of 1-pentene
was added. The solution was transferred through a syringe
to a stainless steel reactor previously closed and purged 2 or
3 times with CO. After this the pressure reactor was used
3
, were obtained from
2
3
2
until the desired pressure (800 psig CO/H , 1:1) and then
*
Corresponding author. E-mail: pankajsh@servidor.unam.mx

6
82 J. Chin. Chem. Soc., Vol. 54, No. 3, 2007
Sharma et al.
Table 1. Reaction effect of several parameters on the hydroformylation of 1-pentene with RhClCO(PPh ) using different stibines
3
2
ligands
Ratio
Ratio
Temperature
Time
(hrs)
Run
Ligand
Yield
1-pentene iso-aldehyde n-aldehyde Ratio n/iso
a
Cat/ligand Pressures
(°C)
1
2
3
4
5
6
7
8
9
TMS
TMS
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/0
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
3/1
1/1
1/3
3/1
1/1
1/3
3/1
1/1
1/3
3/1
3/1
1/1
1/1
1/1
1/3
1/3
1/3
1/3
1/3
1/3
1/1
3/1
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
150
150
150
150
150
150
4
4
4
4
4
4
4
4
4
2
3
2
3
4
2
3
2
3
4
6
4
4
88.46
91.47
78.02
98.07
37.90
48.17
92.21
93.74
89.22
77.30
83.51
86.68
88.63
65.10
73.64
76.46
57.47
63.90
77.30
83.44
88.36
75.46
11.54
08.53
21.98
01.93
62.10
51.83
07.30
03.43
10.28
22.70
16.49
13.40
11.64
34.90
26.36
23.54
42.53
36.10
22.70
15.56
11.64
25.54
29.53
28.18
26.29
40.84
14.47
19.49
26.88
27.77
22.88
26.61
30.98
28.78
28.32
19.50
21.55
23.01
19.14
20.90
26.61
24.20
28.32
22.01
-4
58.93
63.32
51.73
57.23
23.42
28.68
65.33
65.97
06.34
50.69
52.52
57.82
60.04
45.60
52.09
53.45
38.33
43.00
50.69
59.24
60.04
52.45
1.99
2.25
1.97
1.40
1.62
1.47
2.43
2.37
2.90
1.92
1.70
2.00
2.12
2.30
2.42
2.32
2.00
2.06
1.91
2.45
2.12
2.32
TMS
TFS
TFS
TFS
TDMBAS
TDMBAS
TDMBAS
TMS
1
1
1
1
1
1
1
1
1
1
2
2
2
0
1
2
3
4
5
6
7
8
9
0
1
2
TMS
TMS
TMS
without
TMS
TMS
TMS
TMS
TMS
TMS
TMS
TMS
-
3
-5
Experimental conditions: 1-pentene 9.14 ´ 10 mol; RhClCO(PPh ) 9.14 ´ 10 mol; ligand 2 ´ 10 mol; benzene 5 mL; 800 psig
3
2
CO/H total pressure.
2
a
CO/H ratios: 3/1 = P 600 psig and PH2 200 psig; 1/1 = PCO 400 psig and PH2 400 psig; 1/3 = PCO 200 psig and PH2 600 psig.
2 CO
Table 2. Reaction effect of several parameters on the hydroformylation of 1-pentene with RhClCO(PPh ) using different stibines
3
2
ligands
Ratio
Ratio
Temperature Time
Run
Ligand
Yield
1-pentene iso-aldehyde n-aldehyde Ratio n/iso
a
Cat/ligand Pressures
(°C)
(hrs)
2
2
2
2
2
2
2
3
3
3
3
4
5
6
7
8
9
0
1
2
without
TFS
1/0
1/1
3/1
1/1
1/1
1/0
1/1
1/1
1/1
1/1
3/1
3/1
3/1
3/1
3/1
3/1
1/3
1/3
1/3
1/3
120
120
120
080
100
120
120
120
120
120
4
4
4
4
4
4
2
4
5
6
69.15
53.38
42.63
22.10
70.00
69.15
79.40
89.59
94.55
88.63
30.85
47.62
57.37
01.93
03.00
30.85
20.15
10.33
04.98
10.95
48.70
18.84
14.60
08.03
27.27
48.70
20.82
23.80
25.28
24.18
-4
20.45
34.54
28.03
14.07
42.23
20.45
58.58
65.79
69.27
64.45
0.42
1.83
1.92
1.75
1.52
0.42
2.81
2.76
2.74
2.67
TFS
TFS
TFS
without
TDMBAS
TDMBAS
TDMBAS
TDMBAS
-
3
-5
Experimental conditions: 1-pentene 9.14 ´ 10 mol; RhClCO(PPh ) 9.14 ´ 10 mol; ligand 1 ´ 10 mol; benzene 5 mL; 800 psig
3
2
CO/H total pressure.
2
a
CO/H ratios: 3/1 = P 600 psig and PH2 200 psig; 1/1 = PCO 400 psig and PH2 400 psig; 1/3 = PCO 200 psig and PH2 600 psig.
2 CO
warmed in an oil bath at 120 °C for 4 h.; at the end of this
and the gas was liberated. The solution was percholated
through a column packed with alumina and the resulting
time, the reactor was cooled, (final pressure was 650 psig)

Stibines Modified Rh-Catalyzed Hydroformylation
J. Chin. Chem. Soc., Vol. 54, No. 3, 2007 683
yellow solution was analyzed using GC and GC-MS. In the
case of reactions at different time intervals, several experi-
ments in the same conditions were performed.
Rh/TFS catalytic system. It is to be mentioned here that
these experimental conditions do not give reduction prod-
ucts.
Runs 29 to 31 shows that Rh/TDMBAS, in a ratio 1/1,
2
is an active catalytic system even at 1:3 CO/H pressure ra-
RESULTS AND DISCUSSION
tio and produces an appreciable yield of aldehyde in less
time. This study also confirms that a Rh/TDMBAS cata-
From runs 1 to 9, it was observed that Rh/TDMBAS
in a 1:2 ratio produces a catalytic system which is very ac-
tive and is independent of synthesis gas partial pressures. It
also produces higher selectivity in comparison to the other
two systems. The catalytic system Rh/TMS is more active
and selective in comparison to the Rh/TFS system. The last
system exhibits very good activity depending on CO and
lytic system is independent of CO/H
On comparing the catalytic precursors viz. RhClCO-
, RhClCO(PPh + TMS, RhClCO(PPh + TFS,
RhClCO(PPh + TDMBAS, it was observed that ligand
2
partial pressures.
(PPh
3
)
2
3
)
2
3 2
)
3 2
)
effect on the catalytic activity of the system shows a (2-
N,N-dimethylbenzylamine)stibine > (2,4,6-mesityl)stibine
> (2-furyl)stibine pattern which indicates that not only ba-
sicity of the ligand alone is playing role in the activity but
steric effect is also very important and it is a combination of
these two factors which explain the resulting catalytic ac-
2
H partial pressures. It is to be mentioned that none of the
catalytic systems favors the hydrogenation reaction, and
formation of pentane is less than 2%.
6
,7
Runs 10 to 16 show the variation of aldehydes yield
as a time function at different partial pressures using
Rh/TMS as catalytic system. The highest yield of alde-
tivity. It was concluded that the better acceptor character
of stibines is responsible for its important trans effect and
in the homogeneously catalyzed hydroformylation pro-
6
-8
12,13
hydes was obtained at a partial pressure ratio of CO/H
Run 14 shows that without the stibine ligand, the aldehyde
yield is lower. It was also observed that though H partial
2
1:1.
cess. The trans effect
of these stibine ligands may be
responsible for the enhancement of exchange of ligands.
2
pressure is higher, the system does not favour the formation
of pentane.
Received May 15, 2006.
In runs 17 to 20, on comparing the conversions in run
3
, it was observed that there is a decrease in the product
conversion with the increase of temperature. This indicates
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1
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On comparing run 4 with runs 23 to 25 it was ob-
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and gives higher yields with high selectivity for linear alde-
hydes. An increase in ligand/catalyst ratio produces a less
active catalytic species than without the modified catalyst.
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2
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3
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°
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3 2
lytic precursor RhClCO(PPh ) is less active than the

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