4th EucheMs chemistry congress

Poster Session 2
s1268
chem. Listy 106, s257–s1425 (2012)
Poster session 2 - organic chemistry
P - 0 8 1 0
iSoMerizinG oLefine MetAtheSiS
S. BAAder 1 , d. M. ohLMAnn 1 , L. J. GooSSen 1
1 Technische Universität, Fachbereich Chemie, Kaiserslautern,
Germany
Combining a metathesis catalyst with an isomerization
catalyst can lead to a process in which unsaturated compounds
are continuously converted into equilibrium mixtures of double
bond isomers, which are concurrently undergoing olefin
metathesis. Using highly active catalyst systems, the isomerizing
olefin metathesis becomes an effective way to access defined
distributions of unsaturated compounds from olefinic substrates.
When ethylene is the cross metathesis partner, this isomerizing
ethenolysis can be used for the shortening of olefin chains via
stepwise cooperative isomerization and ethenolysis. Following
this process, terminal olefins of higher value are obtained, with
propylene being the only side-product. This new catalytic
transformation is a potentially powerful tool for the transformation
of easy available allylic compounds to the corresponding vinylic
products. This concept is even viable for 4-phenyl-1-butene,
which is converted to styrene via two subsequent isomerizing
ethenolysis steps.
After systematic optimization of the reaction conditions
using a Ru-catalyst, we explored the scope of this new
transformation. Starting from low-price natural products, such as
eugenol (16 € / 100 g), this method gives a direct access to
valuable functionalized styrenes, such as 3-methoxyvinylphenol
(500 € / 100 g), in very good yield and excellent selectivities.
Under these reaction conditions, common functional groups, such
as hydroxy groups, are tolerated. Phenolic substrates are
challenging because of their tendency to polymerize. [1]
Compared to the traditional waste intensive methods like
Wittig reactions, the transition metal catalyzed isomerizing
ethenolysis is an atom-economical and environmentally friendly
alternative for the synthesis of functionalized styrenes. [2]
references:
1. a) R. C. Sovish, J. Org. Chem. 1959, 24, 1345–1347;
b) L. A. Cohen, W. M. Jones, J. Am. Chem. Soc. 1960, 82,
1907–1911.
2. N. Bettach, Y. Le Bigot, Z. Mouloungui, M. Delmas,
A. Gaset, Synthetic Comm. 1992, 22, 513–518.
Keywords: Metathesis; Isomerization; Fatty acids; Sustainable
Chemistry;
4 th EucheMs chemistry congress
P - 0 8 1 1
CoMPArinG the SPeCtrAL ProPertieS of
Pyrene ProBe, LABeL And derivAtive in the
PreSenCe of A nonioniC SurfACtAnt
A. BArAn 1 , G. StinGA 1 , d. f. AnGheL 1 , A. ioveSCu 1 ,
C. MihAiLeSCu 1 , M. tudoSe 2 , P. ionitA 3
1 “Ilie Murgulescu” Institute of Physical Chemistry, Colloid
Chemistry Laboratory, Bucharest, Romania
2 “Ilie Murgulescu” Institute of Physical Chemistry,
Coordination and Supramolecular Chemistry Laboratory,
Bucharest, Romania
3 University of Bucharest, Organic Chemistry Department,
Bucharest, Romania
The behavior of pyrene as probe, label and derivative in
octaethylene glycol mono n-dodecyl ether (C E ), with or without
12 8
polyacrylic acid (PAA), was mainly investigated by steady-state
fluorescence spectroscopy. PAA was home labeled with pyrene
(3% mol). As a probe, pyrene showed a typical behavior,
irrespective of absence or presence of PAA; its emission spectrum
presented five vibronic peaks for monomer and at higher
wavelength and surfactant concentration, the peak corresponding
to the sandwich excimer. As a label on PAA, the emission
spectrum had higher intensity and the same shape, but 4 nm
bathochromically shifted. The peak corresponding to the sandwich
excimer appeared even in surfactant-free solution. The pyrene
derivative was 4-(N',N'-diphenyl-hydrazine)-3,5-dinitrobenzoic
acid 2-oxo-2-pyren-2-yl-ethyl ester. Its fluorescence emission
spectrum had very low intensity, only two monomer peaks (I and 1
I ), no sandwich excimer and a bathochromic shift of 9 nm. It was
5
unexpected that, at the highest surfactant concentration used in
this study, the derivative spectrum presented a 17 nm
bathochromic shift. The data revealed that as a probe, pyrene is
located in free or polymer-bound micelle, close to the core. As a
label, it was first solubilized in the hydrophobic domains (it might
force the polymer to shrink the coil) and, with surfactant addition,
it was solubilized in micelles, closer to the ethylene oxide chains.
The low intensity of the derivative fluorescence spectrum is due
to the self-quenching favored by its structure. The derivative is
probably located even closer to the palisade layer or actually
hanged on it, which may explain the large bathochromic shift. As
the nonionic micelle changes its shape and size, the derivative
may be expelled somehow from the palisade layer. This approach
may be useful in investigating such multi-assembled systems with
the adequate fluorophore.
Keywords: Fluorescent probes; Micelles; Polymers;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc