- Water- and ionic-liquid-soluble branched polythiophenes bearing anionic and cationic moieties
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The synthesis of ionically functionalized branched polythiophenes with either carboxylic acid (anionic, P3T-COOH) or methylimidazolium (cationic, P3T-MIM) end groups is presented. Due to the large number of end groups present in the polymer, the functionalization has a major impact on the solubility of the polymers. In the case of P3T-COOH, the polymer shows a fully reversible phase transfer between organic solvents and water, depending on the pH. Remarkably, the ionic-liquid-modified polymer P3T-MIM is soluble in a room-temperature ionic liquid. The absorption properties are unaffected by the functional end groups.
- Richter, Thomas V.,Buehler, Christian,Ludwigs, Sabine
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- Synthesis of 2-methylidene-1-silacyclohexanes by intramolecular hydrosilylation
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The preparation of various (hex-5-ynyl)silanes was achieved following two different synthetic approaches from readily available materials such as 4-bromobutene, 6-iodohexyne and chlorosilanes. Different reaction conditions for intramolecular hydrosilylation were tested to prepare the corresponding 2-methylidene-1-silacyclohexanes. Notably, the use of Speier's catalyst allowed the regioselective formation of the desired products in moderate yields.
- Díez-González, Silvia,Blanco, Luis
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p. 2033 - 2040
(2008/09/19)
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- Stabilization of crown ether containing supported liquid membranes
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Lipophilic ionophores, synthesized by coupling crown ethers 18-crown-6 and 12-crown-4 at the termini of polysiloxane backbones, have been tested as carriers in the transport of potassium perchlorate through a supported (Accurel) liquid membrane that contains o-nitrophenyl n-octyl ether (NPOE) as the membrane phase. The polysiloxane-coupled crown ethers are able to facilitate the ion transport. The stability of the membrane is enhanced in comparison with that of simple crown ethers like dibenzo-18-crown-6 by at least a factor of 25, because of the high partition coefficient (log PCE = 4.7-27) of the carrier for which the contribution of one siloxane moiety to the value of log PCE is 0.6. Experiments with polysiloxane-coupled crown ethers in poly(dimethylsiloxane) as the membrane phase showed a large decrease of the flux, probably due to the unfavorable partition of the salt between water and poly(dimethylsiloxane). The transport through these membranes can be described by a model, assuming thermodynamic equilibrium at the interfaces and linear concentration gradients of both complex and free crown ether. The experimental relation between the flux and the initial carrier concentration can only be explained when the transport takes place via 2:1 (crown ether:cation) complexes for both polysiloxane-coupled 12-crown-4 and polysiloxane-coupled 18-crown-6.
- Wienk, Martijn M.,Stolwijk, Theodorus B.,Sudh?lter, Ernst J. R.,Reinhoudt, David N.
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p. 797 - 801
(2007/10/02)
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- Greffage d'un modele du NADH sur silice : etude de la reactivite et utilisation en synthese asymetrique
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A NADH model was grafted on a silica matrix.The obtained reagent is efficient in synthesis.The reactivity of the reagent was studied as a function of the length of the chain between the reagent and the surface of the support.A chiral reagent was synthesized and used in asymmetric reactions.Good enantiomeric excesses were obtained.
- Bourguignon, Jean,Tintillier, Patrick,Trefouel, Thierry,Losset, Denis,Dupas, Georges,Queguiner, Guy
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p. 264 - 266
(2007/10/02)
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- Oxygen permeable polymeric materials
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A polymer represented by the general formula STR1 where m is the average degree of polymerization of the polymer, y is an integer from 1 to 3, x is an integer from 1 to 10, A denotes a halogen atom and R denotes an alkyl radical with 1 to 6 carbon atoms.
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