Chemical Engineering August 2014 - 14

ChementatoR
Cobalt: a less-expensive and
more efficient catalyst than rhodium
T
he research group of Shigeki Matsunaga,
associate professor at the University
of Tokyo (Japan; www.f.u-tokyo.
ac.jp/~kanai), in collaboration with Ken
Sakata at Hoshi University, has developed
a new Co-based catalyst system
that outperforms the existing rhodiumbased
catalyst system for the production
of N-fused indol, an important precursor
for pharmaceuticals. The catalyst
combines Co(III) with acetate ions,
which exhibits catalytic performance
based on Lewis acidity intrinsic to cobalt.
Both components are less expensive
and more plentiful than rhodium.
With the new Co-based catalyst system,
Cp*Co(III) [Cp* = 1, 2, 3, 4, 5-pentamethylcyclopentadienil,
C5(CH3)5
-], the
researchers demonstrated a one-pot
synthesis of N-fused indole (diagram)
far superior to the Rh-based catalyst,
Cp*Rh(III). The C2-selective indole
alkenylation/annulation sequence
proceeded smoothly with a catalytic
amount (5 mol%) of [Cp*CoIII(C6H6)](PF6)2
complex and 20 mol% of KOAc in
+
N
O
NR2
R''
N
O
R'
O
R''
Co'''
NR2
One-pot synthesis of N-fused indoles
1,2-dichloroethane (0.1 M) at 130°C in
20 h, giving pyrroloindolones in 58-89%
yield in one pot.
The Cp*Co(III) catalysis was also
shown to be suitable for simple alkenylation
process of N-carbamoyl indoles,
and a broad range of alkynes (including
terminal alkynes) to give C2-alkenylated
indoles with 50-99% yield.
Matsunaga plans to reduce the catalyst
usage and enhance the catalyst life,
which could enhance the turnover numbers
of the catalyst system.
Microporous vanadosilicate efficiently removes
cesium from wastewater
T
he effective removal of Cs+ ions from
contaminated groundwater, seawater,
and radioactive nuclear waste is crucial
for public health and for the operation of
nuclear power plants. Although several
methods for the removal of Cs+ ions have
been developed, there is still a need for
better methods.
Now a team of Korean researchers led
by professor Kyung Byung Yoon from the
Dept. of Chemistry, Sogang University
(Seoul; www.sogang.ac.kr) has reported
a novel microporous vanadosilicate with
mixed-valence vanadium (V+4 and V+5)
ions, which has an excellent ability to
capture and immobilize Cs+ from groundwater,
seawater and nuclear waste. This
vanadosilicate also contains hexadecacoordinated
Cs+ ions, corresponding to
the highest coordination number ever observed
in chemistry.
The performance of Cs+ removers is
often compared in terms of their distribution
coefficient Kd, which is the ratio of the
removed amount of Cs+ ions per amount
of remover (in grems) to the amount of residual
Cs+ ions per mililiter of solution.
Among the various sorbents that have
been developed, crystalline silicotitanate
(CST), currently used at Fukushima,
Japan for Cs+ removal from seawater, has
been shown to be quite effective. The Korean
researchers claim the porous vanadosilicate
material they have developed
- named Sogang University-45, SGU-45
- has Kd values much higher than those
of CST.
The researchers prepared an oxidized
form of SGU-45 material with K+ ions,
K-SGU-45, which has shown a surprising
ability to remove Cs+ from contaminated
seawater. K-SGU-45 has also
proved to be the most suitable material
for the removal of Cs+ ions from stored
nuclear-waste solutions.
The researchers say their work will
lead to the syntheses of various vanadium
and other transition-metal silicates
to capture radioactive nuclides such as
Sr+2 ions.
14 ChemiCal engineering www.Che.Com august 2014
(Continued from p. 12)
limits, the improved sensitivity
offers increased confidence in
results at all measurement levels,
says the company.
the new ei source creates
more than 20 times as many
ions as the current generation
of ei sources, making it possible
to inject smaller sample volumes,
scale down preparation
volumes, and eliminate timeconsuming
and error-prone
pre-concentration steps.
Fuel cells
Vtt technical research Center
of Finland (espoo; www.
vtt.fi) has developed a pilotscale
(50 kw) power plant
based on fuel cells that utilize
byproduct hydrogen from the
process industry. the power
plant has been in operation
at Kemira Chemicals oy's
site in Finland since January
2014. the system produces
electricity from h2 generated
as a byproduct of a sodium
chlorate process at a high
electric efficiency, and is the
first of its kind in the nordic
countries (see also " Fuel
cells move into the CPi plant, "
Chem. Eng., march 2008, p.
25-27). when scaled up to
commercial size, the equipment
enables the reduction
of energy consumption of the
electrolysis process used for
sodium chlorate production
by 10-20%, says Vtt. the
Kemira site's annual electricity
consumption is approximately
578 gwh. ❏
N-fused indoles
R'
cat. Cp*Co'''+ KOAc
58-89% yield
vs
cat. Cp*Rh''': trace
N
R''
R'
http://www.f.u-tokyo http://www.ac.jp/~kanai http://www.vtt.fi http://www.sogang.ac.kr http://www.Che.Com
Chemical Engineering August 2014

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