Chemistry Reference
In-Depth Information
the Ru
31
ions within the cavities of the zeolite with borohydride ions in
aqueous solution, all at room temperature, and (iii) drying the isolated
samples under aerobic conditions at 100
1.0 1C.
63
Only a few Ru/C-catalyzed oxidations of alcohols have been developed so
far; an example is the oxidation of pantoyllactone to give the corresponding
diketone by bubbling O
2
through the lactone at 170 1C (Equation 3.5).
64
More recently, a mild and ecient Ru/C-catalyzed aerobic oxidation of a
variety of alcohols was reported.
65
Combination of Ru/C and cyclodextrins
was effective for the aerobic oxidation of alcohols in water under neutral
conditions.
66
RuCl
2
(PPh
3
)
3
on active carbon catalytically cleaved vic-diols to
give aldehydes with molecular O
2
in PhCF
3
(Table 3.1),
67
and [RuCl
2
-
(p-cymene)]
2
on active carbon is a reusable catalyst for the aerobic oxidation
of general alcohols to the corresponding aldehydes and ketones.
68
d
n
4
r
4
n
g
|
0
OH
O
RuO
2
(3.5)
O
O
o
-PhCl
2
, 180
o
C, 3 h
O
2
(1 atm)
O
O
99.5%
A polymer-incarcerated ruthenium catalyst (PI Ru) (Figure 3.7), prepared
from a polystyrene-based copolymer with RuCl
3
nH
2
O, showed high cata-
lytic activity for the aerobic oxidation of alcohols to the corresponding al-
dehydes and ketones in the presence of a catalytic amount of TEMPO.
69
No
leaching of ruthenium was observed and the catalyst could be recovered and
reused at least 10 times without a decrease in activity.
An ecient polymer-anchored Ru(
III
) catalyst for the aerobic oxidation of
benzyl alcohol was synthesized by sequential attachment of ethylenedia-
mine, salicylaldehyde and RuCl
3
nH
2
O to chloromethylated styrene-
divinylbenzene copolymer with 8% cross-linking, which was characterized
.
Table 3.1 Ruthenium-catalyzed aerobic oxidation of 1,2-octanediol.
OH
O
O
C
6
H
13
C
6
H
13
Ru complex (2.0 mol%)
OH
+
C
6
H
13
C
6
H
13
H
O
PhCF
3
, 60
o
C, 15 h
O
2
(1 atm)
1
2
3
Yield (%)
2
Entry Ru complex
Conversion (%)
3
1
TPAP
20
49
Not detected
2
RuCl
2
(PPh
3
)
3
23
Not detected 48
3 u
3
(CO)
12
No reaction
4
RuCl
3
nH
2
O
3.9
Not detected 42
5
RuO
2
xH
2
O
No reaction
4wt%
RuCl
2
(PPh
3
)
3
/C
Wako Pure
6
92
77
9.5
4wt%
RuCl
2
(PPh
3
)
3
/C
Kurare BP-25
7
87
52
9.0
4wt%
RuCl
2
(PPh
3
)
3
/C
Kurare coal GLC
47
8
77
3.9
9
TPAP/C
Wako Pure
43
74
Not detected
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