The reusability of the aqueous phase, which contains the
rhodiumÈ1a catalyst was also examined (Table 2). Activity
was maintained after Ðve reaction cycles. This result indicates
that the catalyst is very stable and remains in the aqueous
phase.
In conclusion, the biphasic hydroformylation of water-
insoluble internal oleÐns was achieved using a rhodium
complex with the water-soluble calix[4]arene-phosphines 1a
and 1b. This catalytic system resulted in a good level of activ-
ity and reusability giving no emulsion, but the selectivity was
similar to that obtained in MonÑierÏs system. A study con-
cerning the improvement of selectivity for linear aldehydes is
currently in progress.
Scheme 1 Hydroformylation of octenes with proceeding isomer-
ization; (a) isomerization; (b) hydroformylation.
Experimental
catalysts.9 We report herein that the rhodium(I) complexes of
1a and 1b continue to maintain high activity even in the case
of water-insoluble internal oleÐns. Unlike the systems of pre-
cedent,4b,6 a practical level of catalyst reusability was realized,
in addition to high catalytic activity.
The results from the rhodium-catalyzed biphasic hydro-
formylation of internal octenes using 1a and 1b are sum-
marized in Table 1. For comparison, data with respect to
trans-4-octene using a TPPTS ligand and MonÑierÏs com-
bination of TPPTS and 2,6-di-O-methyl-b-cyclodextrin
(DMCD) (Fig. 1) under the same reaction conditions are also
listed.
General
TPPTS and [Rh(acac)(CO) ] were purchased from Strem
Chemicals, Inc. DMCD was purchased from Tokyo Kasei
2
Kogyo Co., Ltd. These reagents were used without further
puriÐcation. Calix[4]arene-phosphine ligands 1a and 1b were
prepared by methods reported in the literature.8 GC analyses
were performed on a Hewlett-Packard Model 6890 gas chro-
matograph equipped with a Ñame ionization detector and a
capilliary column DB-1701 (0.25 mm ] 30 m, 0.25 lm).
Typical procedure for the hydroformylation of internal octenes
When trans-4-octene was treated with a 1 : 1 mixture of
carbon monoxide and hydrogen (4.0 MPa) in water in the
[Rh(acac)(CO) ] (0.008 mmol) and 1a or 1b were dissolved in
2
presence of 0.2 mol% of a [Rh(acac)(CO) ]ÈTPPTS complex
degassed water (3 ml) under argon. The resulting yellowish
2
for 12 h at 140 ¡C,10 trace amounts of nonanals were obtained
solution was then transferred to an autoclave. Internal stan-
dard (decane; 0.40 mmol) and trans-4-octene (4.0 mmol) were
along with a 12% conversion of trans-4-octene (Entry 1). The
addition of DMCD to this reaction mixture increased the con-
version to 74%, along with a mixture of nonanals in 16%
total yield and isomerized oleÐns (Entry 2). Although the
addition of DMCD accelerates the isomerization of trans-4-
octene to other octenes (Scheme 1), a substantially lower yield
of aldehydes was obtained. When the same reaction was
added. The autoclave was pressurized to 4.0 MPa of CO : H
(1 : 1) and heated to 140 ¡C with stirring at 800 rpm. After the
2
reaction, the autoclave was cooled to room temperature and
the reaction mixture was extracted with chloroform (5
ml ] 3). The combined extracts were dried over Na SO and
2
4
analyzed by GC. For recycling experiments, after the reaction
of each cycle, the autoclave was depressurized and the con-
tents were transferred to a Schlenk Ñask under argon. After
extraction with chloroform, the aqueous catalyst solution was
reinjected into the autoclave for the next cycle.
carried out using the [Rh(acac)(CO) ]È1a catalyst (Entry 3), a
2
mixture of nonanals was obtained in a yield of 56% without
detectable oleÐn hydrogenation and alcohol formation at 79%
conversion. Thus, this catalytic system is more efficient than
the DMCD system by a factor of 3.5 for the case of trans-4-
octene. Although over 80% of all aldehydes, that is, nonanals
3È5 were formed from the isomerized oleÐns, the level of selec-
tivity for 1-nonanal, which is a most desirable product in
industry,11 was not acceptable. The selectivity is substantially
the same compared with that observed for the DMCD system.
Comparable activity and selectivity were also obtained when
Notes and references
1
(a) W. A. Herrmann and C. W. Kohlpaintner, Angew. Chem., Int.
Ed. Engl., 1993, 32, 1524; (b) Aqueous-Phase Organometallic
Catalysis: Concepts and Applications, ed. B. Cornils and W. A.
Herrmann, Wiley-VCH, Weinheim, 1998.
2
3
4
E. G. Kuntz, CHEMT ECH, 1987, 17, 570.
the [Rh(acac)(CO) ]È1b catalyst was used (Entry 4). Entries 5
2
M. Beller and J. G. E. Krauter, J. Mol. Catal. A, 1999, 143, 31.
(a) E. MonÑier, G. Fremy, Y. Castanet and A. Mortreux, Angew.
Chem., Int. Ed. Engl., 1995, 34, 2269; (b) E. MonÑier, S. Tilloy, G.
Fremy, Y. Castanet and A. Mortreux, T etrahedron L ett., 1995,
36, 9481; (c) S. Tilloy, F. Bertoux, A. Mortreux and E. MonÑier,
Catal. T oday, 1999, 48, 245.
and 6 show a slightly di†erent result in the hydroformylation
of cis-4-octene and trans-2-octene, respectively.
Table 2 Reuse of the aqueous phase containing rhodium-1a com-
plexa
5
For reviews on inverse phase-transfer catalysis, see: Y. Goldberg,
Phase T ransfer Catalysis: Selected Problems and Applications,
Gordon, Berkshire, 1992, pp. 359È366; (b) C. M. Starks, C. L.
Liotta and M. Halpern, Phase-T ransfer Catalysis: Fundamentals,
Applications, and Industrial Perspectives, Chapman, London,
1994, pp. 179È183.
Cycle
Conversion (%)b
Yield (%)b,c
2 : 3 : 4 : 5 (%)d,e
1
2
3
4
5
90
91
89
91
90
81
87
84
86
83
20 : 19 : 37 : 24
20 : 19 : 37 : 24
20 : 19 : 38 : 23
20 : 19 : 37 : 24
20 : 19 : 37 : 24
6
7
(a) M. T. Reetz and S. R. Waldvogel, Angew. Chem., Int. Ed.
Engl., 1997, 36, 865; (b) M. T. Reetz, J. Heterocycl. Chem., 1998,
35, 1065; (c) M. T. Reetz, Catal. T oday, 1998, 42, 399.
For phosphine ligands incorporating cyclodextrin-receptors, see:
(a) M. Sawamura, K. Kitayama and Y. Ito, T etrahedron: Asym-
metry, 1993, 4, 1829; (b) R. M. Deshpande, A. Fukuoka and M.
Ichikawa, Chem. L ett., 1999, 13; (c) D. Armspach and D. Matt,
Chem. Commun., 1999, 1073.
a Reaction conditions: trans-4-octene (4.0 mmol), 1a (0.064 mmol),
[Rh(acac)(CO) ] (0.008 mmol), molar ratio oleÐn : P : Rh \
2
500 : 16 : 1, H O (3 ml), decane (GC internal standard; 0.40 mmol),
2
CO : H \ 1 : 1, p \ 4.0 MPa, T \ 140 ¡C, t \ 24 h. b Determined by
2
GC. c Yield of nonanals. d Percentage of each nonanal in all nonanals.
8
S. Shimizu, S. Shirakawa, Y. Sasaki and C. Hirai, Angew. Chem.,
Int. Ed., 2000, 39, 1256.
e For structures of isomeric nonanals, see Scheme 1.
778
New J. Chem., 2001, 25, 777È779
Shirakawa
