An amphiphilic resin-dispersion of nanoparticles of platinum (ARP-Pt): A highly active and recyclable catalyst for the aerobic oxidation of a variety of alcohols in water

Article abstract of DOI:10.1002/asia.200800478

An amphiphilic polystyrenepoly(ethylene glycol) (PS-PEG) resindispersion of nanoparticles of platinum (ARP-Pt, 4) was developed with a view towards use in catalysis in an aqueous environment under heterogeneous conditions. ARP-Pt 4 was prepared by the reduction of PS-PEG-NH₂-PtCl₂(C ₂H₄) 3, which was generated by mixing PSPEG-NH₂ 1 and Zeise's salt 2 ([PtCl₃(CH₂CH₂)]), with benzyl alcohol in water (80 °C, 12 h). Benzyl alcohol was an essential reducing agent for the preparation of Pt nanoparticles with a narrow size distribution (=5.9± 0.75 nm) throughout the PS-PEG resin, whereas the reduction of 3 with NaBH₄ gave Pt nanoparticles with broad size distribution (=2-150 nm). ARP-Pt 4 was found to catalyze the aerobic oxidation of a wide variety of alcohols, including non-activated aliphatic and alicyclic alcohols, in water with atmospheric oxygen or air under heterogeneous conditions, and was reused without loss of its catalytic activity, to achieve a highly environmentally-friendly reaction. 2009 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.

Full text of DOI:10.1002/asia.200800478

FULL PAPERS
DOI: 10.1002/asia.200800478
An Amphiphilic Resin-dispersion of Nanoparticles of Platinum (ARP-Pt): A
Highly Active and Recyclable Catalyst for the Aerobic Oxidation of a Variety
of Alcohols in Water
Yoichi M. A. Yamada,[a, b] Takayasu Arakawa,[a, c] Heiko Hocke,[a] and
Yasuhiro Uozumi*[a, b, c]
Abstract: An amphiphilic polystyrene-
poly(ethylene glycol) (PS-PEG) resin-
dispersion of nanoparticles of platinum
(ARP-Pt, 4) was developed with a view
towards use in catalysis in an aqueous
environment under heterogeneous con-
ditions. ARP-Pt 4 was prepared by the
water (808C, 12 h). Benzyl alcohol was
an essential reducing agent for the
preparation of Pt nanoparticles with a
narrow size distribution (f=5.9Æ
0.75 nm) throughout the PS-PEG resin,
whereas the reduction of 3 with NaBH4
gave Pt nanoparticles with broad size
distribution (f=2—150 nm). ARP-Pt 4
was found to catalyze the aerobic oxi-
dation of a wide variety of alcohols, in-
cluding non-activated aliphatic and ali-
cyclic alcohols, in water with atmos-
pheric oxygen or air under heterogene-
ous conditions, and was reused without
loss of its catalytic activity, to achieve a
highly environmentally-friendly reac-
tion.
reduction of PS-PEG-NH2-PtCl
3, which was generated by mixing PS-
PEG-NH2 1 and Zeiseꢀs salt 2 (K[PtCl3
ACHTUNGTRENNUNG(CH2CH2)]), with benzyl alcohol in
2ACHTUGNRTEN(NUNG C2H4)
Keywords: aerobic
oxidation
·
nanoparticles · platinum · sustain-
able chemistry · water
AHCTUNGTRENNUNG
Introduction
The development of highly active immobilized catalysts for
the aerobic oxidation of a variety of alcohols in aqueous
media is a tremendously important topic in chemistry
today.[1] Although aerobic oxidation of non-activated alco-
hols, such as aliphatic and alicyclic alcohols, using immobi-
lized catalysts generally proceeds poorly, the catalytic
system for the aerobic oxidation of activated alcohols, ben-
zylic and allylic alcohols, is fairly developed (Figure 1).[2]
There have been reports of heterogeneous metal catalysts
being used for the aerobic oxidation of various alcohols, but
the catalysts were regularly used in harmful organic sol-
Figure 1. Activated and non-activated alcohols.
vents[3] and/or under vigorous conditions.[4] Recently, we,[5]
Kaneda,[6] Sheldon,[7] Corma,[8] and Sakurai[9] reported the
aerobic oxidation of some aliphatic and alicyclic alcohols in
water using reusable catalysts.[10,11] While acknowledging the
pioneering work in this area, we believe the development of
a novel catalyst system exhibiting a wide range of substrate
tolerance under mild and aqueous conditions still remains a
major challenge. Consequently, we have devised an amphi-
philic polystyrene-poly(ethylene glycol) (PS-PEG) resin-dis-
persion of nanoparticles of palladium (ARP-Pd) that cata-
lyzes the aerobic oxidation of alcohols in water at 1008C.[12]
However, despite such progress, the reactivity and versatility
[a] Dr. Y. M. A. Yamada, Dr. T. Arakawa, Dr. H. Hocke,
Prof. Dr. Y. Uozumi
Institute for Molecular Science
Myodaiji, Okazaki, Aichi 444-8787 (Japan)
Fax : (+81)564-59-5574
E-mail: uo@ims.ac.jp
[b] Dr. Y. M. A. Yamada, Prof. Dr. Y. Uozumi
RIKEN Advanced Research Institute
Wako, Saitama 351-0198 (Japan)
[c] Dr. T. Arakawa, Prof. Dr. Y. Uozumi
The Graduate University for Advanced Studies
Myodaiji, Okazaki, Aichi 444-8787 (Japan)
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Chem. Asian J. 2009, 4, 1092 – 1098

of ARP-Pd for the oxidation of alicyclic and aliphatic alco-
hols was inadequate (see below). We therefore considered
platinum nanoparticles[13,14] since platinum has a stronger
oxidizing ability (Pt/Pt2+ =+1.12 V vs Pd/Pd2+ =+0.95 V)
than palladium. However, deactivation of platinum by
oxygen renders it problematic to reuse efficiently,[15] and Pt
particles possess a latent tendency to explode under the oxi-
dative conditions in organic solvents.[16] Our concept for the
preparation of ARP, where metal particles would be stabi-
lized by amphiphilic resins in aqueous media, should over-
come these drawbacks. Herein, we report a successful exam-
ple for developing amphiphilic resin-dispersion of nanoparti-
cles of platinum (ARP-Pt) and its application to the aerobic
oxidation of a wide variety of alcohols, including not only
benzylic and allylic but also alicyclic and aliphatic alcohols,
in water.[17] It is noteworthy that ARP-Pt efficiently promot-
ed the reaction at 608C with high recyclability.
3 that was reduced with benzyl alcohol in water at 808C for
12 h to afford ARP-Pt 4 as black beads. To elucidate the
structure of 4, several spectroscopic measurements were car-
ried out. High resolution TEM analysis of ARP-Pt 4 re-
vealed, as shown in Figure 2(a)–(d), that the Pt nanoparti-
cles in 4 had a mean diameter of 5.9 nm with a very narrow
size distribution (Æ0.75 nm) throughout the resin, and that
the density of the Pt particles was uniform in the resin (Fig-
ure 2(a)). SEM analysis indicated the existence of no cracks
or fragments in 4. EDS/SEM analysis also confirmed a uni-
form dispersion of Pt throughout the resin. As far as we
know, a uniform dispersion of nanoparticles over the entire
region of insoluble resins with uniform density-distribution
is realized for the first time.[18]
In contrast, the Pt nanoparticles of ARP-Pt 4’ which were
generated by the reduction of 3 with NaBH4 (Scheme 1),
had a very broad size distribution and localized density
(Figure 3). Thus, platinum particles having a diameter of 2–
12 nm were often observed at the shell area of the resin
(Figure 3(c), position (1) and (2)), and more aggregated
platinum particles whose diameter was 50–150 nm were
formed in the core of the resin (Figure 3(c), position (5)).
With an amphiphilic resin catalyst ARP-Pt 4, containing
uniform size- and density-distribution of Pt nanoparticles,
we conducted the oxidation of a variety of primary and sec-
ondary alcohols to the corresponding carbonyl compounds.
Representative results are summarized in Table 1 where sev-
eral palladium (ARP-Pd)-catalyzed results are included for
comparison (Pt vs Pd).[5] The oxidation of 5a (20 mmol;
2.2 g) with 1.0 mol%[19] of ARP-Pt was performed at 608C
for 24 h to give 7a in an isolated yield of 99% (2.4 g)
(Table 1, run 1). Activated alcohols such as benzylic alcohols
6a–c, and allylic alcohols 5b, 6d, and 6e, were transformed
to the corresponding carbonyl compounds 7b and 8a–e in
72–93% yield (runs 3–8).[20] It should be noted that the ben-
zylic ethers as well as the carbon–carbon double bonds were
tolerated under the conditions (entries 5–8), though a plati-
num hydride species should be generated during the alcohol
oxidation process (Scheme 2). We were pleased to find that
the aerobic oxidation of a variety of non-activated alicyclic
alcohols, cyclopentanol (6 f), cyclohexanol (6g), cyclohepta-
nol (6h), and cyclooctanol (6i), also took place smoothly at
608C to provide the corresponding alicyclic ketones in 80–
93% yield (runs 9, 11, 13, and 14). Moreover, it was found
that the non-activated aliphatic primary and secondary alco-
hols, 1-, 2-, 3-, and 4-octanol (5c, 6j–l), were efficiently con-
verted into the corresponding aliphatic carbonyl compounds
in 81–95% yield (runs 15, 16, 18, and 19) under similar con-
ditions. ARP-Pd catalyst exhibited a lower activity even at
higher reaction temperature (runs 10, 12, and 17).
Results and Discussion
A novel ARP-Pt 4 was prepared from commercially avail-
able PS-PEG-NH2 (1) (TentaGel S NH2, f=90 mm) and
Zeiseꢀs salt (KACHTUNGTRENNUNG[PtCl3HCAUTNGTREN(NUGN CH2CH2)]·H2O) (2) (Scheme 1). Thus,
the complexation of 1 (loading value of amino residue:
0.31 mmolgÀ1) and 2 (1 molequiv) was carried out in water
at 258C for 1 h to give PS-PEG resin-supported Pt complex
Scheme 1. Preparation of ARP-Pt 4 and 4’ (with microscopic images of 1
and 4).
Abstract in Japanese:
It is noteworthy that atmospheric air was likewise applied
as an oxidant in this catalytic system (Table 2). Thus, the ef-
ficient conversion of benzylic, alicyclic, and aliphatic secon-
dary alcohols 6a, 6i, and 6j was achieved under atmospheric
pressure of air (21% (v/v) oxygen) in water at 608C to
afford the corresponding ketones 8a, 8i, and 8j in 79%,
93%, and 82% yields, respectively.
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Y. Uozumi et al.
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It is noteworthy that the aerobic oxidation of 6a with
ARP-Pt 4f=10, which was prepared from 10 mm diameter of
PS-PEG resin beads (f=10 mm), gave a similar result to
that obtained with 4 (f=90 mm) (Table 3). Thus, ARP-Pt
4
f=90 and ARP-Pt 4f=10 were prepared from the correspond-
ing PS-PEG-NH2 resin beads (f =90 mm and f=10 mm),
whose calculated spherical surface areas were 3.05ꢂ
10À2 m2 gÀ1 and 2.47 m2 gÀ1, respectively. Pt loading values of
ARP-Pt 4f=90 and ARP-Pt 4f=10 were controlled at the plat-
inum complexation step (from 1 to 3) and were determined
by ICP analysis to both be 0.21 mmolgÀ1. TEM images of
ARP-Pt 4f=90 and ARP-Pt 4f=10 (f=90 mm and f=10 mm)
revealed that Pt nanoparticles were obtained with similar
uniform size- and density-distribution inside each resin
(Figure 4). The catalytic activity of ARP-Pt 4f=90 and ARP-
Pt 4f=10 was examined for the aerobic oxidation of 1-phe-
nethyl alcohol (6a). Thus, the oxidation reactions of 6a
were carried out in water at 608C with 5 mol% Pt of ARP-
Pt 4f=90 and ARP-Pt 4f=10. Acetophenone (8a) was ob-
tained both in 46% yield after 10 h, and in 81% (ARP-Pt
4
f=90) and 86% (ARP-Pt 4f=10) yield, respectively. These
observations indicate that this oxidation took place not only
on the surface of the polymer beads but also throughout the
polymer matrix where the Pt nanoparticles were dispersed
with uniform size- and density-distribution. Thus, the impor-
tance of preparing well-organized and distributed Pt nano-
particles in the resins was demonstrated.
The work-up of the reactions was performed under organ-
ic solvent-free conditions by extraction with supercritical
carbon dioxide, and the recovered ARP-Pt 4 was readily
reused without further purification and/or reactivation.[21]
While, in general, a serious decline of catalytic activity of Pt
nanoparticle catalysts was problematic, catalytic deactiva-
tion of the reused 4 was not observed at all. Thus, after the
oxidation of 6a producing acetophenone (8a) in 82% yield
(Scheme 2), the uniform-sized particle catalyst ARP-Pt 4
was reused 4 times to afford 8a with stable chemical yield
(1st use: 82%, 2nd use: 81%, 3rd use: 84%, 4th use: 92%,
and 5th use: 90%) during which no significant change of the
particle structure was observed by TEM.[22] In contrast, the
random-sized particle 4’ suffered from significant deactiva-
tion during the reusing experiments (yield of 8a; 1st use:
93%, 2nd use: 89%, 3rd use: 88%, 4th use: 79%, and 5th
use: 68%). Notably, ARP-Pt 4 was stable, reusable, and not
flammable under aerobic and aqueous conditions, and was
stored in an open vessel for at least 1 year. Moreover, uni-
form-sized formation of Pt nanoparticles prevented leaching
of Pt from the resin although random formation of Pt parti-
cles caused leaching. In Table 1, entry 16, the obtained 2-oc-
tanone (8j) was not contaminated with platinum residue
(checked by ICP analysis). Over 99.9% of Pt was retained
in the resin of ARP-Pt 4: ICP analysis showed leaching of
Pt to the aqueous solution was <1 ppm, and the aqueous fil-
trate did not show any catalytic activity. These observations
indicate that the aerobic oxidation should take place inside
the polymer matrix, presumably at the surface of the nano-
particles, though the catalysis with homogeneous platinum
Figure 2. a) A TEM image of a section of 4; and a histogram of the size
distribution of Pt particles in 4 (x-axis: diameter of Pt nanoparticles
(nm); y-axis: numbers of Pt nanoparticles (/mm2)); b) a TEM image of 4
at the (1) position, and a histogram of the size distribution of Pt particles
(bar: 10 nm); c) a TEM image of 4 at the (2) position, and a histogram of
the size distribution of Pt particles (bar: 10 nm); d) a TEM image of 4 at
the (3) position, and a histogram of the size distribution of Pt particles
(bar: 10 nm); e) EDS/SEM images of Pt in 4.
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Chem. Asian J. 2009, 4, 1092 – 1098

Dispersed Platinum Nanoparticles for the Aerobic Oxidation of Alcohols in Water
Scheme 2. Recyclability of ARP-Pt 4 and 4a for the aerobic oxidation of
6a to 8a. Scale bar=10 nm.
species leached inside the matrix is still plausible where the
metal species may redeposit back on the nanometal sur-
face.[23] In contrast, the oxidation of 6j mediated by ARP-Pt
4’ was performed in aqueous solution where 4.1 ppm of Pt
was detected with ICP analysis. This means that 0.41% of
Pt leached out from ARP-Pt 4’ through the oxidation reac-
tion.
Conclusions
In conclusion, we have developed a highly active and reusa-
ble amphiphilic resin-dispersion of nanoparticles of platinum
(ARP-Pt). ARP-Pt was a useful catalyst for the aerobic oxi-
dation of a wide variety of alcohols, including benzylic, allyl-
ic, alicyclic, and aliphatic alcohols, in aqueous media with
high recyclability and stability. The reduction of 3 with
benzyl alcohol afforded ARP-Pt 4 with uniform size and dis-
tribution of Pt nanoparticles although that with NaBH4 gave
4’ with disordered size and distribution. Moreover, ARP 4
was readily reused without loss of catalytic activity as op-
posed to 4’.
Experimental Section
General Methods
The aerobic oxidation of alcohols was performed in a glass tube under an
atmospheric pressure of oxygen gas or air in a balloon. Water was deion-
ized with a Millipore system. NMR spectra were recorded on a JEOL
JNM-AL400 spectrometer (400 MHz for 1H, 100 MHz for 13C) or a
Figure 3. a) A TEM image of a section of 4’; b) a TEM image of 4’ at
(1)–(3) positions; (C) TEM images and histograms of 4’ at (1)–(5) posi-
tions; (x-axis: diameter of Pt nanoparticles (nm); y-axis: numbers of Pt
nanoparticles (/mm2)).
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Table 1. The aerobic oxidation of alcohols 5 or 6 with ARP-Pt 4.[a]
entry
substrate
4 [mol%]
time [h]
product
conversion [%]
yield [%]
1[b]
2[b]
5a
1
5
24
8
7a
99
99
99
97
3
4
6a
6b
5
24
36
8a
8b
87
83
82
80
10
5
6c
5b
6d
20
10
5
36
18
15
8c
7b
8d
85
99
88
82
93
87
6[b]
7
8
6e
5
36
8e
99
72
80
9
6 f
6 f
5
5
12
20
8 f
8 f
91
10
ARP-Pd, 1008C
ARP-Pd, 1008C
<2
11
12
6g
6g
5
5
12
20
8g
8g
85
81
93
<2
13
6h
5
12
8h
99
14
6i
5
12
10
8i
99
99
87
95
15[b]
5c
10
7c
16
17
18
6j
6j
6k
5
15
20
30
8j
8j
8k
94
–
85
29
84
ARP-Pd, 1008C
5
10
99
19
6 l
10
36
8 l
99
81
[a] All the reactions were carried out with 4 at 608C in water under atmospheric oxygen unless otherwise noted. [b] One molequiv of K2CO3 was added.
dure for which sections of about 60 nm thick were cut by a cryomicro-
Table 2. The air oxidation of alcohols 6 with ARP-Pt 4.[a]
tome Ultracut UCT (Leica Ltd.) at À1408C from beads, and were picked
up on carbon-coated grids. Supercritical CO2 extraction was performed
with a JASCO SCF-Get. The alcohols, 1-phenylethanol (6b), benzyl alco-
hol (5a), cinnamyl alcohol (5b), 1-octanol (5c), cyclopentanol (6 f), cy-
clohexanol (6g), cycloheptanol (6h), cyclooctanol (6i), 2-octanol (6j), 3-
octanol (6k), 4-octanol (6 l), 4-phenyl-3-buten-2-ol (6d), and 2-cyclohexe-
nol (6e) were purchased from Aldrich or TCI. PS-PEG amino-resin 1
(TentaGel S NH2, average diameter 0.90 mm, 1% divinylbenzene cross-
entry
substrate
4
time
[h]
product
conversion
[%]
yield
[%]
[mol%]
1
2
3
6a
6i
6j
10
20
20
24
60
60
8a
8i
8j
96
99
99
79
93
82
linked, loading value of amino residue 0.31 mmolgÀ1
)
and PS-PEG
amino-resin 1f=10 (TentaGel N NH2, average diameter 10 mm, 1% di-
vinylbenzene cross-linked, loading value of amino residue 0.23 mmolgÀ1
were purchased from RAPP POLYMERETM
[a] All the reactions were carried out with 4 at 608C in water under air.
)
.
All oxidation products are known compounds whose CA registry num-
bers are provided as below:
JEOL JNM-AL500 spectrometer (500 MHz for 1H, 125 MHz for 13C).
SR-MAS 13C NMR spectra were recorded on a JEOL JNM-AL400 spec-
trometer (100 MHz for 13C). 1H and 13C NMR spectra were recorded in
CDCl3 at 258C. Chemical shifts were reported in d ppm referenced to an
internal tetramethylsilane standard for 1H NMR. Chemical shifts of
13C NMR were given relative to CDCl3 as an internal standard (d=
77.0 ppm). The GC-MS was measured by an Agilent 6890 GC/5973N MS
detector that was used with biphenyl as an internal standard for the de-
termination of the GC-yield. ATR-FT-IR spectra were measured with a
FTIR-460 Plus spectrometer (JASCO). TEM images were obtained by
using a transmission electron microscope (JEOL JEM-2100F) operated
at 200 kV. TEM samples were prepared using a cryomicrotoming proce-
5a: 100-51-6; 5b: 108-93-0; 5c: 104-54-1; 6a: 98-85-1; 6b: 19396-73-7; 6c:
96-41-3; 6d: 502-41-0; 6e: 696-71-9; 6 f: 111-87-5; 6g: 123-96-6; 6h: 589-
98-0; 6i: 589-62-8; 6j: 36004-04-3; 6k: 822-67-3; 6l: 139518-33-5; 7a: 65-
85-0; 7b: 557-09-5; 7c: 140-10-3; 8a: 98-86-2; 8b: 1674-37-9; 8c: 120-92-
3; 8d: 108-94-1; 8e: 502-42-1; 8 f: 502-49-8; 8g: 111-13-7; 8h: 106-68-3;
8i: 589-63-9; 8j: 1896-62-4; 8k: 930-68-7; 8l: 139518-43-7.
PS-PEG Resin-supported DichloroACTHNUGRTNEUNG(ethylene)platinum Complex 3
A mixture of PS-PEG amino-resin 1 (3.2 g, loading value of amino resi-
due: 0.31 mmolgÀ1) and Zeiseꢀs salt 2 (372 mg, 1.01 mmol) in water
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Chem. Asian J. 2009, 4, 1092 – 1098

Dispersed Platinum Nanoparticles for the Aerobic Oxidation of Alcohols in Water
Table 3. The effect of the diameter of the resins for the catalytic activi-
ty.[a]
n˜ =3573, 3728 cmÀ1 13C SR-MAS NMR (100 MHz, CDCl3, 258C): d=
;
38.9, 39.5, 39.9, 56.0, 60.9, 66.3, 69.9, 72.0, 101.4, 108.6, 123.1, 127.3,
144.7 ppm.
General Procedure for Catalytic Aerobic Oxidation of Primary Alcohols
in Water
A
mixture of ARP-Pt 4 (0.01 mmol of platinum), primary alcohol
f
(resin)
90 mm
3.05ꢂ10À2
0.21
46%
81%
10 mm
(0.2 mmol), and potassium carbonate (0.2 mmol) in water (2 mL) was
stirred at 608C under an atmospheric pressure of oxygen gas. After being
cooled, the mixture was washed with tert-butyl methyl ether, and acidi-
fied with 5% hydrochloric acid. The mixture was extracted with ethyl
acetate (5ꢂ1 mL). The extract was dried over magnesium sulfate and
concentrated in vacuo to give the corresponding carboxylic acid.
surface area [m2 gÀ1
]
2.47
0.21
46%
86%
Pt loading [mmolgÀ1
yield [10 h]
]
yield [24 h]
[a] All the reactions were carried out with 4 at 608C in water under at-
mospheric oxygen.
General Procedure for Catalytic Aerobic Oxidation of Secondary
Alcohols in Water
A mixture of ARP-Pt 4 (0.01 mmol of platinum) and the secondary alco-
hol (0.2 mmol) in water (2 mL) was stirred at 608C under an atmospheric
pressure of oxygen gas. After it was cooled, the mixture was filtered to
give the resin beads 4 holding the resulting ketone.
Post-treatment Procedure A: Extract with EtOAc
The resin beads were rinsed three times with ethyl acetate (3ꢂ1 mL).
The aqueous layer was extracted with ethyl acetate (3ꢂ1 mL). The com-
bined extracts were dried over magnesium sulfate and concentrated in
vacuo to give the corresponding ketone 8.
Post-treatment Procedure B: Extract with scCO2
The resin beads were extracted with supercritical carbon dioxide
(296 atm, 408C, 24 min), and the remaining product in aqueous media
was isolated by evaporation of the water to afford the corresponding
ketone 8. The recovered catalyst beads were reused without any further
purification or activation.
Acknowledgements
This work was supported by the CREST program, sponsored by the JST,
and the Green-Sustainable Chemical Process project sponsored by the
METI. We also thank the JSPS, the MEXT, and the Uehara Memorial
Foundation for partial financial support of this work.
Figure 4. a) A microscopic image of the resins of f 90 mm and f 10 mm.
b) and c) TEM images of 4 (B: f 90 mm and C: f 10 mm, bar 100 nm).
[1] For recent reviews, see: a) D. Astruc, F. Lu, R. Aranzaes, Angew.
Chem. 2005, 117, 8062–8083; Angew. Chem. Int. Ed. 2005, 44, 7852–
7872; b) T. Mallat, A. Baiker, Chem. Rev. 2004, 104, 3037–3058;
c) R. A. Anderson, K. Griffin, P. Johnson, P. L. Alsteres, Adv. Synth.
Catal. 2003, 345, 517–523.
(20 mL) was shaken at room temperature for 1 h. The mixture was fil-
tered and the resulting resin beads were rinsed three times with water
and dried in vacuo to give 3 (3.5 g, loading value of platinum residue:
0.28 mmolgÀ1): IR: n˜ =1602, 3595, 3728 cmÀ1
;
13C SR-MAS NMR
(100 MHz, CDCl3, 258C): d=39.9, 44.4, 70.1, 74.0, 104.2, 125.2, 127.5,
[2] Recent examples of the Pd-catalyzed aerobic oxidation of alcohols
under homogeneous conditions, see: a) K. P. Peterson, R. C. Larock,
J. Org. Chem. 1998, 63, 3185; b) T. Nishimura, T. Onoue, K. Ohe, S.
Uemura, Tetrahedron Lett. 1998, 39, 6011; c) T. Nishimura, T.
Onoue, K. Ohe, S. Uemura, J. Org. Chem. 1999, 64, 6750; d) N. Ka-
kiuchi, Y. Maeda, T. Nishimura, S. Uemura, J. Org. Chem. 2001, 66,
6620; e) B. A. Steinhoff, S. R. Fix, S. S. Stahl, J. Am. Chem. Soc.
2002, 124, 766; f) S. S. Stahl, J. L. Thorma, R. C. Nelson, M. A.
Kozee, J. Am. Chem. Soc. 2001, 123, 7188; g) D. R. Jensen, J. S.
Pugsley, M. S. Sigman, J. Am. Chem. Soc. 2001, 123, 7475; h) M. S.
Sigman, D. R. Jensen, Acc. Chem. Res. 2006, 39, 221.
[3] The aerobic oxidation in organic solvents, see: a) K. Hara, S.
Tayama, H. Kano, T. Masuda, S. Takakusagi, T. Kondo, K. Uosaki,
M. Sawamura, Chem. Commun. 2007, 4280–4282; b) H. Miyamura,
R. Matsubara, Y. Miyazaki, S. Kobayashi, Angew. Chem. 2007, 119,
4229; Angew. Chem. Int. Ed. 2007, 46, 4151; c) M. S. Kwon, N. Kim,
C. M. Park, J. S. Lee, K. Y. Kang, J. Park, Org. Lett. 2005, 7, 1077–
1079; d) N. Kakiuchi, Y. Maeda, T. Nishimura, S. Uemura, J. Org.
Chem. 2001, 66, 6620–6625.
144.8 ppm.
PS-PEG Resin-dispersion of Platinum Nanoparticles (ARP-Pt) 4
A mixture of 3 (3.5 g; loading value of platinum residue: 0.28 mmolgÀ1
)
and benzyl alcohol (5 mL) in water (24 mL) was shaken at 808C for 12 h.
The mixture was filtered, and the resulting resin beads were rinsed three
times with water (at 608C for 20 min) and three times with acetone (at
258C for 5 min), then dried in vacuo to give ARP-Pt 4 (3.4 g; loading
value of platinum residue: 0.29 mmolgÀ1): IR: n˜ =3557, 3661 cmÀ1 13C
;
SR-MAS NMR (100 MHz, CDCl3, 258C): d=40.1, 61.3, 66.6, 70.2, 104.0,
125.4, 127.8, 145.1 ppm.
PS-PEG Resin-dispersion of Platinum Nanoparticles 4’
A mixture of 3 (3.5 g; loading value of platinum residue: 0.28 mmolgÀ1
)
and NaBH4 (531 mg, 14 mmol) in water (25 mL) was shaken at 248C for
1 h. The mixture was filtered and the resulting resin beads were rinsed
five times with water and three times with acetone, then dried in vacuo
to give 4’ (3.4 g; loading value of platinum residue; 0.29 mmolgÀ1): IR:
Chem. Asian J. 2009, 4, 1092 – 1098
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1097

Y. Uozumi et al.
FULL PAPERS
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Received: December 23, 2008
Revised: February 20, 2009
Published online: May 22, 2009
1098
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Chem. Asian J. 2009, 4, 1092 – 1098