- Gold-nanoparticle-based catalysts for the oxidative esterification of 1,4-butanediol into dimethyl succinate
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The oxidation of 1,4-butanediol and butyrolactone have been investigated by using supported gold, palladium and gold-palladium nanoparticles. The products of such reactions are valuable chemical intermediates and, for example, can present a viable pathway for the sustainable production of polymers. If both gold and palladium were present, a significant synergistic effect on the selective formation of dimethyl succinate was observed. The support played a significant role in the reaction, with magnesium hydroxide leading to the highest yield of dimethyl succinate. Based on structural characterisation of the fresh and used catalysts, it was determined that small gold-palladium nanoalloys supported on a basic Mg(OH)2 support provided the best catalysts for this reaction. Twice as nice: The oxidation of 1,4-butanediol and butyrolactone has been investigated over supported gold, palladium and gold-palladium nanoparticles. The oxidation of both hydroxyl groups of α,γ-diols has previously proved to be difficult. Small AuPd alloy nanoparticles on a basic Mg(OH)2 support provide the best catalysts for this reaction. Copyright
- Brett, Gemma L.,Miedziak, Peter J.,He, Qian,Knight, David W.,Edwards, Jennifer K.,Taylor, Stuart H.,Kiely, Christopher J.,Hutchings, Graham J.
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p. 1952 - 1958
(2013/11/06)
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- Understanding the solvent effect on the catalytic oxidation of 1,4-butanediol in methanol over Au/TiO2 catalyst: NMR diffusion and relaxation studies
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The effect of water on the catalytic oxidation of 1,4-butanediol in methanol over Au/TiO2 has been investigated by catalytic reaction studies and NMR diffusion and relaxation studies. The addition of water to the dry catalytic system led to a decrease of both conversion and selectivity towards dimethyl succinate. Pulsed-field gradient (PFG)-NMR spectroscopy was used to assess the effect of water addition on the effective self-diffusivity of the reactant within the catalyst. NMR relaxation studies were also carried out to probe the strength of surface interaction of the reactant in the absence and presence of water. PFG-NMR studies revealed that the addition of water to the initial system, although increasing the dilution of the system, leads to a significant decrease of effective diffusion rate of the reactant within the catalyst. From T1 and T2 relaxation measurements it was possible to infer the strength of surface interaction of the reactant with the catalyst surface. The addition of water was found to inhibit the adsorption of the reactant over the catalyst surface, with the T1/T2 ratio of 1,4-butanediol decreasing significantly when water was added. The results overall suggest that both the decrease of diffusion rate and adsorption strength of the reactant within the catalyst, due to water addition, limits the access of reactant molecules to the catalytic sites, which results in a decrease of reaction rate and conversion. Copyright
- D'Agostino, Carmine,Brett, Gemma L.,Miedziak, Peter J.,Knight, David W.,Hutchings, Graham J.,Gladden, Lynn F.,Mantle, Mick D.
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p. 14426 - 14433
(2013/01/15)
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- Synthesis of biobased N-methylpyrrolidone by one-pot cyclization and methylation of γ-aminobutyric acid
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N-Methylpyrrolidone (NMP) is an industrial solvent that is currently based on fossil resources. In order to prepare it in a biobased way, the possibility to synthesize NMP from γ-aminobutyric acid (GABA) was investigated, since GABA can be obtained from glutamic acid, an amino acid that is present in many plant proteins. Cyclization of GABA to 2-pyrrolidone and subsequent methylation of 2-pyrrolidone to NMP was achieved in a one-pot procedure, using methanol as the methylating agent and a halogen salt (i.e. ammonium bromide) as a catalyst. A selectivity above 90% was achieved, as well as a high conversion. Methylation of 2-pyrrolidone could also be done with dimethyl carbonate, but then the selectivity for NMP was less (67%).
- Lammens, Tijs M.,Franssen, Maurice C. R.,Scott, Elinor L.,Sanders, Johan P. M.
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experimental part
p. 1430 - 1436
(2010/09/05)
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- Method for producing 1,4-butanediol
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A process for preparing 1,4-butanediol and, if desired, gamma-butyrolactone and THF by oxidizing butane or benzene to form a product stream including maleic anhydride, absorbing maleic anhydride from the product stream with a high-boiling inert solvent in an absorption stage to give a liquid absorption product, esterifying the liquid absorption product with a C1-C5 esterifying alcohol in an esterification stage to form an esterification product comprising the corresponding diester and high-boiling inert solvent, then hydrogenating the esterification product to give a hydrogenation product which comprises the products of value, 1,4-butanediol and, if desired, gamma-butyrolactone and tetrahydrofuran and the esterifying alcohol and which is separated by distillation into the products of value and the esterifying alcohol, and recycling the esterifying alcohol to the esterification zone, which comprises separating the esterification product into the diester and the inert solvent by distillation under reduced pressure prior to the hydrogenation, recycling the inert solvent to the absorption stage, and hydrogenating the diester in the liquid phase over a fixed-bed catalyst.
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Page column 7
(2008/06/13)
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- Enantiomerically pure tetrahydro-5-oxo-2-furancarboxylic esters from dialkyl 2-oxoglutarates
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Enantiomerically pure tetrahydro-5-oxo-2-furancarboxylic esters can be prepared either by enzymatic resolution of the racemic γ-lactones themselves or by bioreduction with baker's yeast of dialkyl 2-oxoglutarates and subsequent cyclization of the resulting dialkyl 2-hydroxyglutarates. The best results were obtained by the former route, by which the desired compounds were isolated in high enantiomeric excess. Bioreductions were less satisfactory. In fact the hydroxyester intermediates were initially formed as racemic mixtures and their final enantiomeric enrichment was reached by asymmetric destruction, occurring in the bioreaction medium, however at the same time large amounts of alkyl 4-hydroxybutanoates were formed as side products.
- Drioli, Sara,Nitti, Patrizia,Pitacco, Giuliana,Tossut, Laura,Valentin, Ennio
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p. 2713 - 2728
(2007/10/03)
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- Total Synthesis of Allocyathin B2, a Metabolite of Bird's Nest Fungi
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Allocyathin B2 has been synthesized using aldol reactions for construction of rings A and B, introduction of the side chain for ring B, cyclization of the acetyl group into a lactone, and construction of the seven-membered diene aldehyde during the last step.
- Tori, Motoo,Toyoda, Naoko,Sono, Masakazu
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p. 306 - 313
(2007/10/03)
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- Reactivite du nitrite de sodium. V. Action sur les amino-acides, peptides et proteines
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The action of sodium nitrite on various amino-acids was re-examined in conditions approximating to a biological medium. 13C-NMR provides evidence of the existence of intramolecular ring closures and the formation of 5-membered rings with ornithine, citrulline and arginine.The reaction of cystine shows the opening of the sulphur bridges, whereas cysteine leads to the formation of carboxy-thiiran and 3-sulpho-lactic acid.The hydrolysis of the amide bonds of asparagine and glutamine is complete whereas the peptides studied - carnosine and aspartam - do not undergo hydrolysis of the peptide linkage.However, the first deamination of glutathion (γ-Glu-Cys-Gly) induces the peptide link to be broken and a cyclization with the formation of lactone to occur.A second deamination takes place on the cysteinyl residue released and allows the formation of a thiiran by intramolecular cyclization with the thiol group.The formation of thiiran was also observed with oxidized glutathion which has an S-S bridge.Finally, the formation of nitrosamines was detected by 15N-NMR during the reaction of sodium nitrite with two commercial products available to the general public.
- Gouesnard, Jean-Paul
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- Further Studies on a Site-specific Hydrogen Transfer Observed in Electron Capture Negative Ion Chemical Ionization Mass Spectrometry of Hydroxyamine Pentafluoropropionate Derivatives
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Further studies have demonstrated that the site-specific hydrogen transfer process involved in the formation of the m/z 145 anion of β-hydroxyamine pentafluoropropionate (PFP) derivatives observed under electron capture negative ion chemical ionization conditions occurs when the two functional groups are separated by up to five carbon atoms.Deuterium labelling has established that the site specificity, transfer of a hydrogen atom from the carbon adjacent to nitrogen to the OPFP group, is maintained in 4-amino-butan-1-ol-N,O-(PFP)2.The corresponding PFP derivatives of the N-methylaminoalkanol- (PFP)2 derivatives lack the m/z 145 species with m/z 163, -, being the base anion.Substitution of alkyl groups on the carbon adjacent to oxygen results in a diminution of the ion intensity at m/z 145 with a marked increase in the intensity of m/z 144.The formation of the m/z 145 and 144 anions is proposed to proceed through the intervention of a fluoride ion-molecule complex as outlined in Scheme 1 with the product ion distribution dependent on which of the two pathways is preferred.
- Low, G. K.-C.,Duffield, A. M.
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p. 595 - 599
(2007/10/02)
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- The products of hydrolysis of cyclic orthoesters as a function of pH and the theory of stereoelectronic control
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The acid hydrolysis of cyclic orthoesters 1, 3-6 (R=Me), and 2 (R=Me and Et) as a function of pH was studied.The bicyclic orthoester 5 yields mainly the hydroxy-ester (less than 5percent lactone), and this result is essentially independent of pH.For the other orthoesters, the relative percentage of products differs for each case and varies with pH.At pH3.These results are explained on the basis of the stereoelectronic theory for the cleavage of tetrahedral intermediates.
- Deslongchamps, Pierre,Lessard, Jean,Nadeau, Yves
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p. 2485 - 2492
(2007/10/02)
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