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Homogene Katalyse
1
Prof. Dr. Herbert Plenio, Organometallic Chemistry, Alarich-Weiss-Str. 12, TU
Darmstadt,64287 Darmstadt, Germany, [email protected],
http://www.chemie.tu-darmstadt.de/plenio/akplenio/startseite/index.de.jsp
• Wie kann man schneller, effizienter und umweltfreundlicher
organische Moleküle und Polymere synthetisieren?
• Wie funktionieren diese Synthesewerkzeuge?
Development, Application and
Understanding of Synthetic Tools!
RESEARCH TOPICS
superior synthetic tools =
Development of new catalysts
better synthesis =
new approaches for the synthesis
of organic molecules and polymers
precise mechanism =
mechanistic studies of transition-metal
catalyzed transformations
CATALYSIS
Pd-catalyzed cross coupling reactions
Ru-catalyzed Olefin Metathesis
fluorescent dyes
www.lego.com
Herbert Plenio
2
What is Olefin Metathesis?
3 see: http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2005/speedread.html
Herbert Plenio
A catalytic reaction which rearranges substituents
around a carbon-carbon double bond.
fast and low-loading
RCM catalysis
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100 ppm 88%
100 ppm 89%
15 ppm 91%
50 ppm 89% P. Kos, R. Savka, H. Plenio, Adv. Synth. Catal. 2013, 355, 439
http://onlinelibrary.wiley.com/doi/10.1002/adsc.201200956/abstract
Research Topic: Polymers
switched ROMP
5 L. H. Peeck, S. Leuthäußer, H. Plenio, Organometallics 2010, 29, 4339; doi: 10.1021/om100628f
E/Z = 0.64 E/Z = 0.85
Stereoblock co-polymers with distinct materials properties can be synthesized
using redox-switchable catalysts for ring-opening metathesis polymerization
Herbert Plenio
Research Topic: Renewables
Ethenolysis of natural rubber and tire rubber
n
natural rubber
cis-Polyisoprene
Hevea brasiliensis
n
[Ru] -catalyst
++
+ethene
On the ethenolysis of end-of-life tire granulates
S. Wolf, H. Plenio, Green Chem. 2013, 15, 31; http://dx.doi.org/10.1039/C2GC36417D
The ethenolysis of natural rubber or tire
rubber granulate leads to the depoly-
merization of the polymer, resulting in the
facile formation of small terpenes, which
might be suitable for the synthesis of
fragrances.
Herbert Plenio
6
organic solubles obtained after
ethenolysis of ELT powder
7
[Ru]
7 barethenetoluene
80 oC
fest
flüssig
10 g of ELT yield up to 5 g of organic solubles
10 g of ELT require 0.04 g of ruthenium complex
Research topic: Fluorescent dyes
Tagged catalyst complexes
8 T. Vorfalt, K.-J. Wannowius, V. Thiel, H. Plenio, Chem. Eur. J. 2010, 16, 12312; doi: 10.1002/chem.201001832
Transition metal complexes tagged with
fluorescent dyes can be used to monitor
an ongoing catalytic transformation via
fluorescence spectroscopy or microscopy
down to the level of individual molecules.
Herbert Plenio
Research Topic: Mechanism
Understanding how catalysts work
9 .
On the Mechanism of the Initiation Reaction in Grubbs-Hoveyda Complexes
V. Thiel, M. Hendann, K. J. Wannowius, H. Plenio, J. Am. Chem. Soc. 2012, 134, 1104;
http://dx.doi.org/10.1021/ja208967h
Progress in catalysis critically relies on detailed mechanistic
understanding. The development of olefin metathesis over
the last decades from ill-defined, low-activity catalysts to
powerful synthetic tools is an excellent example for this.
Herbert Plenio
Research Topic: Mechanism
Understanding how catalysts work
350 400 450 500 5500.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
ab
so
rba
nce
nm]
0 50 100 150 200 250 300 350 4000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
absorbance at 377 nm
absorb
ance
time (s)
equaton y = A1*exp(-x/t1) + y0
R^2 0.99995
value error
y0 0.18493 1.77929E-4
A1 0.71613 0.00108
t1 42.28923 0.09367
0.0 0.5 1.0 1.5 2.0 2.50.00
0.02
0.04
0.06
0.08
kobs (
s-1)
[BuVE] (mol·L-1)
kobs = a·[olefin]/(1+b·[olefin]) + c·[olefin]
M CH2
MM
M
[2+2]
[2+2]
The activation of precatalysts leads to the generation of a
catalytically active species. Analysis of initiation kinetics
with time-dependent spectroscopic techniques provides
a clearer picture of the elementary steps of precatalyst
activation.
Herbert Plenio
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Research topic: Sensors Fluorescent paper strip based H2-detection
11 P. Kos, H. Plenio, Angew. Chem. Int. Ed. 2015, 54, DOI: 10.1002/anie.201506918
http://onlinelibrary.wiley.com/doi/10.1002/anie.201506918/abstract
Synthese
a) plain paper strip
b) paper strip impregnated with a solution of complex 8b
c) the same strip following exposure to H2 = fluorescent!
a) b) c)
