- Ketonic decarboxylation reaction mechanism: A combined experimental and DFT study
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The ketonic decarboxylation of carboxylic acids has been carried out experimentally and studied theoretically by DFT calculations. In the experiments, monoclinic zirconia was identified as a good catalyst, giving high activity and high selectivity when compared with other potential catalysts, such as silica, alumina, or ceria. It was also shown that it could be used for a wide range of substrates, namely, for carboxylic acids with two to eighteen carbon atoms. The reaction mechanism for the ketonic decarboxylation of acetic acid over monoclinic zirconia was investigated by using a periodic DFT slab model. A reaction pathway with the formation of a β-keto acid intermediate was considered, as well as a concerted mechanism, involving simultaneous carbon-carbon bond formation and carbon dioxide elimination. DFT results showed that the mechanism with the β-keto acid was the kinetically favored one and this was further supported by an experiment employing a mixture of isomeric (linear and branched) pentanoic acids. This way or that? Monoclinic zirconia has great potential as a catalyst for ketonic decarboxylation of carboxylic acids (see picture). A combined experimental and DFT study shows a route involving a β-keto acid intermediate as the kinetically preferred reaction pathway. Copyright
- Pulido, Angeles,Oliver-Tomas, Borja,Renz, Michael,Boronat, Mercedes,Corma, Avelino
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- Reactivities of mixed organozinc and mixed organocopper reagents, 2. Selective n-alkyl transfer in tri-n-butylphosphine-catalyzed acylation of n-alkyl phenylzincs; an atom economic synthesis of n-alkyl aryl ketones
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Tri-n-butylphosphine-catalyzed acylation of mixed n-alkyl phenylzincs with aromatic acyl halides in THF is efficient in selective transfer of n-alkyl groups to produce n-alkyl aryl ketones in good yields. This route provides an atom economic organocatalyzed alternative to transition metal-catalyzed acylation of di-n-alkylzincs.
- Erdik, Ender,Pekel, ?zgen ?mür
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experimental part
p. 1501 - 1503
(2009/06/21)
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- Effets de cryptands et activation de bases. VI. Reactions d'organo-lithiens.
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Utilization of the cryptand shows the need of electrophilic catalysis by the Li(1+) ion in the nucleophilic addition of organolithium compounds to ketones, esters, or carboxylic acids.When nucleophilic addition is inhibited, organolithium reagents enolyze ketones or esters.When activated by cryptation of Li(1+), organolithium reagents attack ethers in a few minutes.With alkyl halides, only elimination takes place: exchange and nucleophilic substitution are not observed any longer in the presence of the cryptand.Generally speaking, the cryptand seems to enhance the basicity of the organolithium reagent, and nucleophilicity does not manifest itself any more.
- Perraud, Robert,Handel, Henri,Pierre, Jean-Louis
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p. 283 - 288
(2007/10/02)
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- SOME ORGANIC LITHIUM COMPOUNDS AS INITIATORS OF THE ANIONIC POLYMERIZATION OF METHYL METHACRYLATE
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The presence of α-lithio ketone in the initiation mixture formed by a reaction between butyllithium and methyl pivalate was demonstrated.In the initiation of the polymerization of methyl methacrylate α-lithio ketones exhibit high efficiency, which can be enhanced by the effect of lithium alkoxides, in particular of lithium tert-butoxide.
- Lochmann, Lubomir,De, Rajib L.,Janca, Josef,Trekoval, Jiri
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p. 2761 - 2765
(2007/10/02)
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