Catalytic olefin epoxidation with molecular oxygen over supported amidate-bridged platinum blue complexes

Article abstract of DOI:10.1081/SCC-120001503

The platinum complexes, [Pt₄(NH₃)₈((CH₃) ₃CCONH)₄]-(NO₃)₅ and [Pt₂(NH₃)₄((CH₃) ₃CCONH)₂](NO₃)₄, supported on a surface of silica gel, AL₂O₃, activated carbon, and poly-(4-vinylpyridine) are active heterogeneous catalysts for the liquid phase epoxidation of various olefins under 1 atm of dioxygen in the presence of isobutyraldehyde.

Full text of DOI:10.1081/SCC-120001503

This article was downloaded by: [University of Chicago Library]
On: 14 October 2014, At: 12:46
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer
House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsyc20
CATALYTIC OLEFIN EPOXIDATION WITH MOLECULAR
OXYGEN OVER SUPPORTED AMIDATE-BRIDGED
PLATINUM BLUE COMPLEXES
a
a
Wanzhi Chen , Jun Yamada & Kazuko Matsumoto
a
Department of Chemistry, School of Science and Engineering, Waseda University ,
Okubo, Shinjuku, Tokyo, 169-8555, Japan
b
CREST , Japan Science and Technology Corp.
Published online: 21 Aug 2006.
To cite this article: Wanzhi Chen , Jun Yamada & Kazuko Matsumoto (2002) CATALYTIC OLEFIN EPOXIDATION WITH
MOLECULAR OXYGEN OVER SUPPORTED AMIDATE-BRIDGED PLATINUM BLUE COMPLEXES, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 32:1, 17-22, DOI: 10.1081/SCC-120001503
To link to this article: http://dx.doi.org/10.1081/SCC-120001503
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of
the Content. Any opinions and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied
upon and should be independently verified with primary sources of information. Taylor and Francis shall
not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other
liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or
arising out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

SYNTHETIC COMMUNICATIONS, 32(1), 17–22 (2002)
CATALYTIC OLEFIN EPOXIDATION
WITH MOLECULAR OXYGEN OVER
SUPPORTED AMIDATE-BRIDGED
PLATINUM BLUE COMPLEXES
Wanzhi Chen, Jun Yamada, and Kazuko Matsumoto*
Department of Chemistry,
School of Science and Engineering,
Waseda University, Okubo,
Shinjuku 169-8555, Tokyo, Japan, CREST,
Japan Science and Technology Corp.
ABSTRACT
The platinum complexes, [Pt (NH ) ((CH ) CCONH) ]-(NO )
3 5
4
3 8
3 3
4
and [Pt (NH ) ((CH ) CCONH) ](NO ) , supported on a
3 4
2
3 4
3 3
2
surface of silica gel, Al O , activated carbon, and poly-
2
3
(
4-vinylpyridine) are active heterogeneous catalysts for the
liquid phase epoxidation of various olefins under 1atm of
dioxygen in the presence of isobutyraldehyde.
There has recently been enormous interest in the coordination and
organometallic chemistry of platinum(III) complexes, because of their fasci-
nating reactivity resulting from the electron deficiency of the high-valent
metal centers. We have reported several novel reactions, i.e. activation of
*
Corresponding author.
1
7
Copyright & 2002 by Marcel Dekker, Inc.
www.dekker.com

ORDER
REPRINTS
1
8
CHEN, YAMADA, AND MATSUMOTO
C-H bonds of ketones by amidate-bridged Pt(III) complexes to give the
ketonyl-platinum(III) dinuclear complexes and coordination of olefins in
1
,2
water to give b-hydroxyalkyl-platinum(III) complexes. It was also found
that amidate-bridged Pt(III) complexes catalyze the oxidation of terminal
olefins to ketones and promote dihydroxylation of olefins in acidic aqueous
3
,4
solutions.
Transition-metal complex-catalyzed epoxidation of olefins has been of
great interest due to the importance of epoxides as valuable synthetic inter-
mediates. Various soluble metal complexes have been reported to be effec-
5
6
tive expoxidation catalysts, for instance, ruthenium and manganese
7
porphyrins, Mn and Fe triamidoamine complexes, and Ru-phosphine com-
8
plexes together with peroxides or molecular oxygen. Heterogeneous cata-
lysts based on metals, metal ions or metal complexes adsorbed on supports
such as carbon, aluminas, silicas, zeolites, and clays, polymer-supported
Ru-porphyrin complexes have been used for liquid phase oxidation together
9
–14
with oxidant such as H O , KHSO , NaClO or organic peroxides.
2
2
5
A simple catalytic system using sacrificial aldehydes as the oxygen-acceptor
agent and dioxygen as the source of oxygen, which was first reported by
1
Mukaiyama, have also been employed in other laboratories.
5
8,13
Although amidate-bridged platinum(III) complexes catalyze the oxi-
dation of olefins in biphasic aqueous-organic solutions, only cyclic olefins
can be epoxidized with low turnover number (less than 25 moles of epoxides
1
6
per mole of platinum blue complexes). The true active catalyst in the
reactions was found to be the platinum(III) dimer complex produced
2
from the oxidation of the platinum blue complex. By extending these our
earlier results on the organometallic and catalytic chemistry of platinum
blue complexes, here we report the immobilization of the platinum blue
complexes on SiO , Al O , activated carbon, and poly(4-vinylpyridine),
2
2
3
and their catalytic properties for the expoxidation of various olefins in the
presence of a sacrificial aldehyde under atmospheric pressure of molecular
oxygen at room temperature.
Five solid catalysts were prepared from [Pt (NH ) ((CH ) CCONH) ]-
4
3 8
3 3
4
(
NO3)5 or [Pt (NH ) ((CH ) CCONH) ](NO ) , and are abbreviated as
2 3 4 3 3 2 3 4
Pt /C, Pt /Al O , Pt /SiO , Pt /PVP (PVP ¼ poly(4-vinylpyridine) 2%
2
2
2
3
2
2
2
cross-linked), and Pt /C.
4
Table 1shows the representative results for the epoxidation of cyclo-
hexene and styrene catalyzed by various supported platinum complexes in
the presence of a sacrificial aldehyde and molecular oxygen. Although it is
known that alkenes can be epoxidized only with molecular oxygen and
1
7,18
isobutyraldehyde in the absence of a metal complex,
the data listed in
Table 1obviously demonstrate that supported platinum blue complexes
afford higher yield of epoxides. Simultaneously, isobutyric acid was also

ORDER
REPRINTS
CATALYTIC OLEFIN EPOXIDATION
19
Table 1. Catalytic Epoxidation of Olefins by Various Supported Platinum(III)
Complexes*
Catalyst
Carbon
Pt /C
Substrate
Product
Time (h) Epoxide Yield (%)
Cyclohexene 1,2-epoxycyclohexane
Cyclohexene 1,2-epoxycyclohexane
Styrene
Cyclohexene 1,2-epoxycyclohexane
Styrene 2-phenyloxirane
Cyclohexene 1,2-epoxycyclohexane
Cyclohexene 1,2-epoxycyclohexane
Styrene
Cyclohexene 1,2-epoxycyclohexane
Cyclohexene 1,2-epoxycyclohexane
Styrene
Cyclohexene 1,2-epoxycyclohexane
Styrene 2-phenyloxirane
24
6
49.0
99.0
52.6
99.0
83.7
36.6
43.8
19.4
22.5
52.6
10.7
12.2
26.7
2
Pt
Pt
2
/C
/C
2-phenyloxirane
6
8
4
Pt /C
4
14
24
15
15
24
14
14
8
SiO
Pt/SiO
Pt /SiO
2
2
2-phenyloxirane
2
2
Al
Pt
2
O
/Al
3
2
2
O
3
Pt /Al O
2-phenyloxirane
2
2
2
2
3
Pt
Pt
/PVP
/PVP
14
*
The reaction conditions are given in the experimental section.
formed as the side-product from the oxidation of isobutyraldehyde. In order
to test the efficiency of the supported metal complexes, the reactions in the
presence of Al O , SiO and carbon were performed respectively. The results
2
3
2
demonstrate that platinum complexes apparently facilitate the epoxidation.
All the supported catalysts showed much higher catalytic activity than those
of our earlier reported soluble platinum complexes in aqueous-organic
2
,16
biphasic solutions.
It is especially noteworthy that styrene was not epox-
idized in the previous biphasic solution reactions, but is epoxidized in the
present supported system in good yield. And also the reaction proceeds
much faster in the present system.
It can be seen from Table 1that the catalyst activity is dependent upon
the catalyst carriers. The two activated carbon supported catalyst, Pt /C and
2
Pt /C, did not show significant difference in the cyclohexene epoxidation.
4
Higher conversions were achieved with Pt /C and Pt /C for the epoxi-
2
4
dation of cyclohexene with 99% yield of 1,2-epoxycyclohexane within
1
ꢀ
6
platinum. Both [Pt (NH ) ((CH ) CCONH) ](NO ) and [Pt (NH ) -
h, which corresponds to a frequency of 71turnovers h
per mole of the
4
3 8
3 3
4
3 5
2
3 4
(
cyclohexene and styrene than Pt /Al O , Pt /SiO , and Pt /PVP. Probably
(CH ) CCONH) ](NO ) supported on carbon afforded better yield for
3 3 2 3 4
2
2
3
2
2
2
the interaction between the platinum complexes with the hydroxyl groups
or adsorbed water molecules on the surface of SiO and Al O , and the
nitrogen on the pyridine rings of poly(4-vinylpyridine) prevents the
2
2
3

ORDER
REPRINTS
2
0
CHEN, YAMADA, AND MATSUMOTO
approaching of olefins to the platinum complexes and therefore lower their
catalytic activities.
Catalyst leaching was observed when Pt /PVP was employed after long
2
time running, and the reaction mixture turned to be slightly yellow. Although
the catalyst leaching in other cases was not found during the reaction courses,
the side-product, isobutyric acid, induced metal loss is expected.
The activated carbon supported catalyst, Pt /C, was also employed to
2
catalyze the epoxidation of other olefins under the mild conditions of room
temperature and atmospheric pressure of dioxygen, and the data are
collected in Table 2. In the epoxidation reactions of all olefins studied, the
catalyst showed excellent selectivity for the epoxides, only trace amount of
cyclohex-2-enone being detected by GC-MS in the case of cyclohexene. The
formation of cyclohex-2-enone was previously also observed in large
amount as by-product in the previous biphasic solution reaction under
similar conditions. Generally, cyclic olefins and internal alkenes give
better yield than terminal linear olefins; only 5% of 1,2-epoxyoctane was
detected for 1-octene. Only one olefinic bond of cyclohex-1,4-diene was
epoxidized under these mild conditions. It is noted that in the absence of
isobutyraldehyde no cyclohexane oxide was observed by GC-MS for
cyclohexene using Pt /C as catalyst. Although trans-cinnamaldehyde bears
2
Table 2. Epoxidation of Various Olefins Catalyzed by Pt /C*
2
Substrate
Product
Time (h)
Epoxide Yield (%)
Cyclopentene
Cyclohexene
Cyclooctene
1,2-epoxycyclopentane
1,2-epoxycyclohexane
1,2-epoxycyclooctane
1,2-epoxycyclohex-4-ene
1,2-epoxy-
6
6
14
14
8
92.2
99.0
35.5
55.7
60.6
Cyclohex-1,4-diene
-methylcyclohexene
1
1
-methylcyclohexane
1
2
-octene
-octene
1,2-epoxyoctane
2,3-epoxyoctane
2,3-diphenyloxirane
2,3-epoxy-
14
15
14
15
5.0
100
88.0
69.1
cis-stilbene
trans-
cinnamaldehyde
trans-
3-phenylpropanal
2,3-epoxy-
a
48
No reaction
cinnamaldehyde
Cyclohexene
Cyclohexene
3-phenylpropanal
1,2-epoxycyclohexane
1,2-epoxycyclohexane
b
24
24
No reaction
No reaction
b
*
The reactions were carried out under atmospheric molecular oxygen in CH
2
Cl
room temperature in the presence of isobutyraldehyde. No additive. PhIO or
Me NO was used as the oxidant instead of O
2
at
a
b
3
2
.

ORDER
REPRINTS
CATALYTIC OLEFIN EPOXIDATION
21
potential oxygen-transferring group, it was not oxidized to its corresponding
epoxide in the absence of the additional aldehyde; the –CHO group did
not initiate efficiently the intramolecular oxidation reaction like the addi-
tional aldehyde. In the presence of isobutyraldehyde, however, the epoxide
was obtained nearly in 70% yield. It illustrates that the additional oxygen-
transferring agent plays a dominating role for the oxygenation reaction.
PhIO and Me NO were also tested as oxygen-transferring agent, but no
3
epoxidation reaction was observed.
The results presented above show that platinum blue complexes immo-
bilized onto both inorganic and organic carriers catalyze the epoxidation of
olefins smoothly with moderate to good yield under mild conditions.
Although the heterogeneous catalysts have the advantage of recoverability
and give much higher turnover than their soluble counterpart, the catalysts
still suffer from the drawback of using a sacrificial aldehyde as the oxygen-
transferring agent. Further improvement of the catalysts is required to avoid
the use of sacrificial aldehyde and realizes a clean, economic route for the
production of epoxides.
EXPERIMENTAL
Supported platinum catalysts were prepared by impregnation of each
support with an aqueous solution of either [Pt (NH ) ((CH ) CCONH) ]-
4
3 8
3 3
4
(
NO ) or [Pt (NH ) ((CH ) CCONH) ](NO ) , at room temperature. The
3 5 2 3 4 3 3 2 3 4
mixtures were stirred until the impregnation solution turned to colorless.
The supported catalysts were collected by filtration and washed with water
and acetone successively, and then dried in vacuum. The loading of plati-
num was 2.3% for activated carbon and 1.2% for Al O , SiO and PVP.
2
3
2
The epoxidation of olefins was performed under room temperature and
atm of molecular oxygen, typically as follows. A reaction flask under O 2
1
atmosphere was charged with solid catalyst (in each reaction, the catalysts
containing 0.024 mmol of platinum were used regardless of their loading),
1
0 ml of CH Cl , 10 mmol of substrate, and 3 ml of isobutyraldehyde. The
2 2
reaction was run at room temperature with constant stirring by a magnetic
stirrer. After completion or interruption of the reaction, the catalyst was
1
filtrated off, and the solution was subjected to GC or H NMR analysis.
REFERENCES
1. Matsumoto, K.; Sakai, K.; Nishi, K.; Tokisue, Y.; Ito, R.; Nishide, T.;
Shichi, Y. J. Am. Chem. Soc. 1992, 114, 8110.

ORDER
REPRINTS
2
2
CHEN, YAMADA, AND MATSUMOTO
2. Matsumoto, K.; Nagai, Y.; Matsunami, J.; Mizuno, K.; Abe, T.;
Somazawa, R.; Kinoshita, J.; Shimura, H. J. Am. Chem. Soc. 1998,
12, 2900.
3. Lin, Y.; Takeda, S.; Matsumoto, K. Organometallics 1999, 18, 4897.
4. Lin, Y.; Misawa, H.; Matsumoto, K. unpublished results.
5. Higuchi, T.; Ohtake, H.; Hirobe, M. Tetrahedron Lett. 1989, 30, 6545.
6. Meunier, B.; Guilmet, E.; De Carvalho, M.; Poilblanc, R. J. Am.
Chem. Soc. 1984, 106, 6668.
7. Chen, J.; Woo, L.K. J. Organomet. Chem. 2000, 601, 57.
8
. Stoop, R.M.; Bauer, C.; Setz, P.; Wo
Organometallics 1999, 18, 5691.
. Laufer, W.; Meiers, R.; Holderich, W. J. Mol. Catal. A: Chemical
999, 141, 215.
0. Raja, R.; Sankar, G.; Thomas, J.M. Chem. Commun., 1999, 829.
¨
rle, M.; Wong, Y.H.; Mezzetti, A.
9
¨
1
1
1
1
1. Andrus, M.B.; Poehlein, B.W. Tetrahedron Lett. 2000, 41, 1013.
2. Chisem, J.; Chisem, I.C.; Rafelt, J.C.; Macquarreie, D.J.; Clark, J.H.
Chem. Commun. 1997, 2203.
13. Gao, H.; Angelici, R. Synth. Commu. 2000, 1239.
14. Yu, X.; Huang, J.; Yu, W.; Che, C. J. Am. Chem. Soc. 2000, 122, 5337.
15. Takai, T.; Yamada, T.; Mukaiyama, T. Chem. Lett. 1990, 1657.
16. Matsumoto, K.; Mizuno, K.; Abe, T.; Kinoshita, J.; Shimura, H.
Chem. Lett. 1994, 1325.
17. Kaneda, K.; Haruna, S.; Hamamoto, M.; Nishiyama, Y.; Ishii, Y.
Tetrahedron Lett. 1992, 33, 6827.
18. Anzenbacher, Jr. P.; Kral, V.; Jursikova, K.; Gunterova, J.; Kasal, A.
J. Mol. Catal. A: Chem. 1997, 118, 63.
Received in Japan October 20, 2000

Request Permission or Order Reprints Instantly!
Interested in copying and sharing this article? In most cases, U.S. Copyright
Law requires that you get permission from the article’s rightsholder before
using copyrighted content.
All information and materials found in this article, including but not limited
to text, trademarks, patents, logos, graphics and images (the "Materials"), are
the copyrighted works and other forms of intellectual property of Marcel
Dekker, Inc., or its licensors. All rights not expressly granted are reserved.
Get permission to lawfully reproduce and distribute the Materials or order
reprints quickly and painlessly. Simply click on the "Request
Permission/Reprints Here" link below and follow the instructions. Visit the
U.S. Copyright Office for information on Fair Use limitations of U.S.
copyright law. Please refer to The Association of American Publishers’
(AAP) website for guidelines on Fair Use in the Classroom.
The Materials are for your personal use only and cannot be reformatted,
reposted, resold or distributed by electronic means or otherwise without
permission from Marcel Dekker, Inc. Marcel Dekker, Inc. grants you the
limited right to display the Materials only on your personal computer or
personal wireless device, and to copy and download single copies of such
Materials provided that any copyright, trademark or other notice appearing
on such Materials is also retained by, displayed, copied or downloaded as
part of the Materials and is not removed or obscured, and provided you do
not edit, modify, alter or enhance the Materials. Please refer to our Website
User Agreement for more details.
Order now!
Reprints of this article can also be ordered at
http://www.dekker.com/servlet/product/DOI/101081SCC120001503