Polyether phosphine oxide induced phase separable homogeneous catalysis for hydroformylation of higher olefins

Article abstract of DOI:10.1016/S0022-328X(02)01980-0

Triarylphosphine oxide bearing polyether group (PETAPO) gives high activity and allows easy separation of the catalyst for hydroformylation of 1-decene. PETAPO induces phase separable homogeneous catalysis for aqueous organic biphasic and nonaqueous hydroformylation reaction.

Full text of DOI:10.1016/S0022-328X(02)01980-0

Journal of Organometallic Chemistry 664 (2002) 1Á4
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www.elsevier.com/locate/jorganchem
Communication
Polyether phosphine oxide induced phase separable homogeneous
catalysis for hydroformylation of higher olefins
a,b,
b
a
Liu Xiaozhong ꢀ, Li Hongmei , Kong Fanzhi
Department of Organic Chemistry, Dalian University of Technology, Dalian 116012, People’s Republic of China
a
b
Department of Chemistry, Institute of Organic Chemistry, Peking University, Beijing 100871, People’s Republic of China
Received 11 July 2002; received in revised form 24 September 2002; accepted 28 September 2002
Abstract
Triarylphosphine oxide bearing polyether group (PETAPO) gives high activity and allows easy separation of the catalyst for
hydroformylation of 1-decene. PETAPO induces phase separable homogeneous catalysis for aqueous organic biphasic and non-
aqueous hydroformylation reaction.
#
2002 Elsevier Science B.V. All rights reserved.
Keywords: Phosphine oxide; Hydroformylation; Catalyst separation
Phosphine oxides, proved to be weak coordinating
ligands to metal center and long believed to be one of
reasons for deactivation of hydroformylation catalysts,
have received some special attention in hydroformyla-
tion and found their industrial application [1]. Triphe-
nylphosphine oxide (TPPO) was employed industrially
as ligand in Rh-catalyzed hydroformylation of higher
olefins such as octenes and nonenes [1b,1c]. Triphenyl-
phosphine (TPP) was added in need to stabilize rhodium
before separation of products by distillation and oxi-
dized to TPPO before reuse of the separated catalyst.
Meanwhile TPPO presented higher activity in hydro-
formylation of octenes than TPP [1d]. Bidentate analo-
catalyst separation [2]. Water-soluble phosphines,
mostly ionic phosphines have been believed to be an
important factor in controlling selectivity, activity and
catalyst separation. Recently introduction of polyether
group to phosphines has become an available approach
to prepare water-soluble ligands [2b,2c]. Polyether
triarylphosphine analogues were successfully demon-
strated for aqueous organic biphasic hydroformylation,
selective hydrogenation and water gas shift reactions etc
[2b,2c,2e].
Herein for the first time we report a new triarylpho-
sphine oxide bearing polyether moiety (polyether triar-
ylphosphine oxide, PETAPO) for hydroformylation of
1-decene. PETAPO gave high activity for rhodium
catalyzed aqueous organic biphasic hydroformylation
of 1-decene and the separated aqueous solution contain-
ing catalyst was employed in several successive reactions
without obvious loss in activity. Meanwhile in the
absence of water, quantitative catalyst precipitated
from reaction mixture on cooling to room temperature,
which also provides another potential approach to
catalyst separation.
gues of phosphine oxides such as P(O)Ã
P(O)ÃP, which containing two coordinating sites (OÃ
OÃO, OÃ
/
N, P(O)Ã
/
O,
/
/N,
/
/
P) to metal center, [1e,1f,1g] were also
reported to be promoting ligands in rhodium catalyzed
hydroformylation reactions.
An ever-increasing consideration in hydroformylation
of higher olefins has been taken by using aqueous
organic biphasic catalysis mainly in tackling with
PETAPO was prepared by ethoxylation reaction of
tri-(p-hydroxyphenyl)phosphine oxide (THPPO) as fol-
lows [3,4].
ꢀ
Corresponding author. Tel.: ꢁ
275-1708
E-mail address: xzchem@hotmail.com (L. Xiaozhong).
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86-10-6275-9643; fax: ꢁ86-10-
/
6
0
022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 9 8 0 - 0

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L. Xiaozhong et al. / Journal of Organometallic Chemistry 664 (2002) 1Á4
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ð1Þ
PETAPO turns to be yellow or brown viscous oil after
removing solvent. N value was determined by area of H
2.7 and 3.5 ppm of phosphines in heptane were detected
at room temperature, 100 and 150 8C, respectively.
That means that only 0.224% of loaded phosphine
dissolves in heptane event at 150 8C. As a result,
PETAPO turns to be another phase immiscible with
heptane between room temperature and 150 8C. These
results exclude role of Thermoregulated Phase-Trans-
ferred Catalysis in the above biphasic catalysis [2e,5].
Since molecules with polyether moiety has long con-
sidered as amphiphilic group and easily induces micelles
or vesicles in its aqueous dispersion, [6] hence micellar
catalysis is proposed for the above aqueous organic
hydroformylation. In aqueous media, these polyether
phosphine oxides form micelles or vesicles incorporating
substrate and catalysts in it, inducing catalytic active
microreactors in which reaction goes on. Further study
about its formation of vesicles is in progress experimen-
tally.
1
of glycol moiety to that of H of Ph group from its H-
3
1
NMR spectra. From P-NMR spectra of PETAPO, it
has a characteristic peak at 29.6 ppm. PETAPOs are
presented to be water soluble when N over or equal to 7
and give increasing water solubility with longer poly-
ether chain.
Table 1 collects catalytic experimental results of
hydroformylation of 1-decene with rhodium catalyst
formed in situ with ligand L1Á
/
L3. Entries 1Á7 give good
/
activity of PETAPO’s rhodium complexes. The aqueous
solution containing catalysts is easily separated by
decantation, hence as entries 1Á
aqueous solution is recycled four times without loss in
activity. Table 1 also indicated about 0.6Á3.1% of
/5 revealed, the separated
/
loaded rhodium and less than 1.0% phosphine loss in
organic product phase in the first reaction run. From
point of catalyst retentation, longer polyether moiety
benefits rhodium and phosphine recovery, which is
ascribed to higher water solubility of PETAPO with
longer moiety.
As described above, only a little PETAPO, e.g.
0.115% of L , dissolves in heptane at room temperature,
1
which means potential easy separation of the catalyst
after reaction. Table 2 reveals catalytic results on non-
aqueous hydroformylation of 1-decene with in situ
formed Rh/PETAPO complexes as catalysts. Experi-
mentally Rh/PETAPO precipitated quantitatively as
viscous oil from reaction mixture at room temperature
In order to get some insight into where this reaction
carries on, we took an analysis of PETAPO’s (L Nꢂ22
/
1
as a model) solubility in heptane at 25, 100 (reaction
temperature) and 150 8C. Upon reaction conditions 1.8,
Table 1
AqueousÁorganic biphasic hydroformylation of 1-decene with PETAPO/Rh complexes as catalyst
/
a
TOF (hꢃ1
b
c
Rh loss (%/ppm)
c
P loss (%/ppm)
Entry
Ligand
, Nꢂ22
2nd run
3rd run
4th run
5th run
Conv.(%)
Aldehyde yield (%)
n/iso
)
1
2
3
4
5
6
7
L
1
92
90
91
89
89
95
96
90
87
88
87
86
93
93
32:68
32:68
33:67
32:68
33:67
32:68
32:68
225
223
231
232
233
225
230
2.5/6.5
2.3/6.0
1.5/3.9
1.3/3.4
1.1/2.8
0.8/2.1
0.6/1.6
0.22/3.4
0.21/3.3
0.19/3.0
0.17/2.7
0.13/2.0
0.10/1.6
0.08/1.3
L
L
2
3
Nꢂ30
Nꢂ45
a
1
0 mmol 1-decene, 0.10 mol% [Rh(acac)(CO)
(1:1), Temperature 100 8C, tꢂ4 h.
Moles 1-decene converted to aldehydes per mole Rh per hour.
Rhodium and phosphine loss to the organic product as percentage loaded Rh or P and ppm as corresponding concentration of Rh and P in the
2
], 2.0 mol% ligand L1Á
/
4 2
L , 4.0 ml solution (heptaneꢁinternal standard), 6.0 ml H O, 7.0 Mpa
COÁ
/H
2
b
c
organic product.

L. Xiaozhong et al. / Journal of Organometallic Chemistry 664 (2002) 1Á
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3
Table 2
Non-aqueous hydroformylation of 1-decene with PETAPO/Rh complexes as catalyst
a
P/Rh (mol molꢃ1
b
b
Rh loss (%/ppm)
b
P loss (%/ppm)
Entry
Ligand
, Nꢂ20
2nd run
3rd run
4th run
5th run
)
Conv.(%) Aldehyde yield (%)
n/iso TOF
8
9
L
1
20
83
81
81
80
79
88
91
76
59
81
78
79
78
78
86
90
74
58
35:65 202
32:68 204
33:67 213
34:66 216
35:65 222
35:65 215
33:67 228
34:66 185
36:64 170
4.5/11.1
3.0/7.83
2.5/6.5
2.5/6.5
2.1/5.4
5.0/13
1.7/26.5
1.6/25.0
1.4/21.9
1.2/18.7
1.0/15.6
3.0/46.8
6.5/101.5
3.1/48.4
3.9/60.8
10
11
12
13
14
15
16
L
2
L
3
L
1
L
1
Nꢂ30
Nꢂ45
20
20
40
60
8.0/20.7
2.1/5.4
1.5/3.9
a
2 2
10 mmol 1-decene, 0.10 mol% [Rh(acac)(CO) ], 4.0 ml solution (heptaneꢁinternal standard), 7.0 Mpa CO/H (1:1), Temperature 100 8C, tꢂ4
h.
b
Indicated the same as in Table 1.
and the catalyst could be employed in the successive
reaction runs by decanting organic product phase
Acknowledgements
(
entries 8Á
/
12 in Table 2). About 4.5Á
/
8.0% of Rh and
The research was partially supported by the National
Nature Science Foundation of China. The authors
thank Professor Dr Jin Zilin for his advice in catalysis
and thanks are also given to Dr Li Ji for his ICP-AES
analysis.
1
.7Á6.5% of phosphine leached in organic product phase
/
after the first reaction. From entry 8, 15 and 16, higher
P/Rh ratio supports retentation of rhodium and phos-
phine from reaction mixture. This may be reasoned by
that more PETAPO promote in stabilizing rhodium
complex. Upon reaction conditions, PETAPO turns to
be an mobile fluid immiscible with heptane at tempera-
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1
heptane even at 150 8C. It is made sense that this
reaction takes place in liquid phosphine phase in which,
PETAPO acts as ligand and reactant medium as well. In
comparison of Table 1 with Table 2, PETAPO give
lower activity in non-aqueous system than that in
aqueous organic biphasic system.
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[
[
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In conclusion, a novel water-soluble phosphine oxide
PETAPO, first prepared by introduction of polyether
group to triarylonosphine oxide, proves to be an
efficient ligand for rhodium catalyzed hydroformylation
of 1-decene. The catalyst appears to be phase separable
from reaction mixture in aqueous organic system and
non-aqueous system after reaction.
obtained as brown viscous liquid after removing solvent. Nꢂ
/
22.
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ꢃ1
H
3
/
/
2
H
4
C
(
3
7
6
P
ꢁ
CDCl
3
3
4
/Na ]:

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