The Experts below are selected from a list of 552 Experts worldwide ranked by ideXlab platform
Steven V Ley - One of the best experts on this subject based on the ideXlab platform.
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teflon af 2400 mediated gas liquid contact in continuous flow Methoxycarbonylations and in line ftir measurement of co concentration
ChemInform, 2012Co-Authors: Peter Koos, Ulrike Gross, Anastasios Polyzos, Matthew Obrien, Ian R Baxendale, Steven V LeyAbstract:Using Teflon AF-2400 to mediate gas-liquid contact in a concentric Tube-in-Tube configuration enables the continuous flow palladium-catalyzed Methoxycarbonylation of alkyl and aryl iodides in a reliable manner.
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teflon af 2400 mediated gas liquid contact in continuous flow Methoxycarbonylations and in line ftir measurement of co concentration
Organic and Biomolecular Chemistry, 2011Co-Authors: Peter Koos, Ulrike Gross, Anastasios Polyzos, Matthew Obrien, Ian R Baxendale, Steven V LeyAbstract:We report on the development of a continuous flow process for the palladium catalysed Methoxycarbonylation of aryl, heteroaromatic and vinyl iodides and an aryl bromide using a Teflon AF-2400 based Tube-in-Tube reactor to mediate the selective permeation of carbon monoxide into solution at elevated pressures. The low volume of pressurised gas within the reactor (5.6 mL) offers the potential for an enhanced safety profile compared to batch processes. We also present preliminary results for the use of in situFTIR to measure solution concentrations of carbon monoxide and demonstrate the use of a second reactor to effect the removal of carbon monoxide from the flow stream.
David J Colehamilton - One of the best experts on this subject based on the ideXlab platform.
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mechanism of alkyne alkoxycarbonylation at a pd catalyst with p n hemilabile ligands a density functional study
Chemistry: A European Journal, 2014Co-Authors: Luke Crawford, David J Colehamilton, Eite Drent, Michael BuhlAbstract:A detailed mechanism for alkyne alkoxycarbonylation mediated by a palladium catalyst has been characterised at the B3PW91-D3/PCM level of density functional theory (including bulk solvation and dispersion corrections). This transformation, investigated via the Methoxycarbonylation of propyne, involves a uniquely dual role for the P,N hemilabile ligand acting co-catalytically as both an in situ base and proton relay coupled with a Pd(0) centre, allowing for surmountable barriers (highest ΔG(≠) of 22.9 kcal mol(-1) for alcoholysis). This proton-shuffle between methanol and coordinated propyne accounts for experimental requirements (high acid concentration) and reproduces observed regioselectivities as a function of ligand structure. A simple ligand modification is proposed, which is predicted to improve catalytic turnover by three orders of magnitude.
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polymerisable di and triesters from tall oil fatty acids and related compounds
Green Chemistry, 2013Co-Authors: Marc R L Furst, Thomas Seidensticker, David J ColehamiltonAbstract:Tall Oil Fatty Acids, a low value side product from the paper industry containing mainly oleic and linoleic acids, are used for producing the polyester precursor, dimethyl 1,19-nonadecanedioate by Methoxycarbonylation in the presence of [Pd2(dba)3], 1,2-bis(ditertiarybutylphosphinomethyl)benzene and methanesulfonic acid in methanol. The Methoxycarbonylation of methyl linoleate has been used to identify other products formed and approaches to their minimisation have been developed. It has also been used for the production of trimethyl heptadecanetricarboxylates. Finally, conjugated unsaturated esters of different chain length (up to 16 C atoms), some of them available from plant oils, are subjected to Methoxycarbonylation to give α,ω-diesters.
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polymer precursors from catalytic reactions of natural oils
Green Chemistry, 2012Co-Authors: Marc R L Furst, Ronan Le Goff, Dorothee Quinzler, Stefan Mecking, Catherine H Botting, David J ColehamiltonAbstract:Dimethyl 1,19-nonadecanedioate is produced from the Methoxycarbonylation of commercial olive, rapeseed or sunflower oils in the presence of a catalyst derived from [Pd2(dba)3], bis(ditertiarybutylphosphinomethyl)benzene (BDTBPMB) and methanesulphonic acid (MSA). The diester is then hydrogenated to 1,19-nonadecanediol using Ru/1,1,1-tris-(diphenylphosphinemethyl)ethane (triphos). 1,19-Nonadecadienoic acid is hydrogenated to short chain oligoesters, which can themselves be hydrogenated to 1,19-nonadecanol by hydrogenation in the presence of water.
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dicarboxylic acid esters from the carbonylation of unsaturated esters under mild conditions
Inorganic Chemistry Communications, 2005Co-Authors: Cristina Jimenezrodriguez, Graham R Eastham, David J ColehamiltonAbstract:Abstract The Methoxycarbonylation of unsaturated acids or esters catalysed by Pd complexes of bis(ditertiarybutyl-phosphinomethyl)benzene (DTBPMB) produces α,ω-diesters with selectivities >95%, even if the double bond is deep in the chain or conjugated to the carbonyl group; unsymmetrical esters can also be produced with high selectivity.
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Methoxycarbonylation of vinyl acetate catalysed by palladium complexes of bis ditertiarybutylphosphinomethyl benzene and related ligands
Chemical Communications, 2005Co-Authors: Adam J Rucklidge, George E Morris, David J ColehamiltonAbstract:High selectivities to methyl acetoxypropanoate esters (b : l up to 3.6 : 1) are obtained from the Methoxycarbonylation of vinyl acetate catalysed by palladium complexes of bis(ditertiarybutylphosphinomethyl)benzene in the presence of acid, provided that the acid concentration does not exceed that of the free phosphine.
Peter Koos - One of the best experts on this subject based on the ideXlab platform.
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teflon af 2400 mediated gas liquid contact in continuous flow Methoxycarbonylations and in line ftir measurement of co concentration
ChemInform, 2012Co-Authors: Peter Koos, Ulrike Gross, Anastasios Polyzos, Matthew Obrien, Ian R Baxendale, Steven V LeyAbstract:Using Teflon AF-2400 to mediate gas-liquid contact in a concentric Tube-in-Tube configuration enables the continuous flow palladium-catalyzed Methoxycarbonylation of alkyl and aryl iodides in a reliable manner.
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teflon af 2400 mediated gas liquid contact in continuous flow Methoxycarbonylations and in line ftir measurement of co concentration
Organic and Biomolecular Chemistry, 2011Co-Authors: Peter Koos, Ulrike Gross, Anastasios Polyzos, Matthew Obrien, Ian R Baxendale, Steven V LeyAbstract:We report on the development of a continuous flow process for the palladium catalysed Methoxycarbonylation of aryl, heteroaromatic and vinyl iodides and an aryl bromide using a Teflon AF-2400 based Tube-in-Tube reactor to mediate the selective permeation of carbon monoxide into solution at elevated pressures. The low volume of pressurised gas within the reactor (5.6 mL) offers the potential for an enhanced safety profile compared to batch processes. We also present preliminary results for the use of in situFTIR to measure solution concentrations of carbon monoxide and demonstrate the use of a second reactor to effect the removal of carbon monoxide from the flow stream.
Zi-sheng Chao - One of the best experts on this subject based on the ideXlab platform.
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A proposed mechanism for the Methoxycarbonylation of 1,6-hexanediamine with DMC over ZnAlPO
2011Co-Authors: Da-lei Sun, Jian-ru Deng, Zi-sheng ChaoAbstract:Copyright information:Taken from "Catalysis over zinc-incorporated berlinite (ZnAlPO) of the Methoxycarbonylation of 1,6-hexanediamine with dimethyl carbonate to form dimethylhexane-1,6-dicarbamate"http://journal.chemistrycentral.com/content/1/1/27Chemistry Central Journal 2007;1():27-27.Published online 7 Nov 2007PMCID:PMC2211281.
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ch3coona as an effective catalyst for Methoxycarbonylation of 1 6 hexanediamine by dimethyl carbonate to dimethylhexane 1 6 dicarbamate
ChemInform, 2010Co-Authors: Da-lei Sun, Jian-ru Deng, Shunji Xie, Caijuan Huang, Eli Ruckenstein, Zi-sheng ChaoAbstract:Methoxycarbonylation of 1,6-hexanediamine (HDA) by dimethyl carbonate (DMC) was carried out, using, for the first time, CH3COONa as catalyst. The effects of the solvent, reaction temperature, reaction time, and catalyst amount, were investigated. A yield as high as 99.0% of dimethylhexane-1,6-dicarbamate 2 has been obtained at a temperature of 348 K and a reaction time of 6 h. Mechanistic studies revealed that N-substituted acetamide, as the active intermediate product, and NaOH were first formed via the reaction between HDA and CH3COONa. A further reaction between the N-substituted acetamide and DMC generated carbamates and methyl acetate, via a hexatomic ring intermediate. The CH3COONa catalyst was finally recovered through the reaction between NaOH and methyl acetate, which thus completed the catalytic cycle.
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catalysis over zinc incorporated berlinite znalpo4 of the Methoxycarbonylation of 1 6 hexanediamine with dimethyl carbonate to form dimethylhexane 1 6 dicarbamate
Chemistry Central Journal, 2007Co-Authors: Da-lei Sun, Jian-ru Deng, Zi-sheng ChaoAbstract:The alkoxycarbonylation of diamines with dialkyl carbonates presents promising route for the synthesis of dicarbamates, one that is potentially 'greener' owing to the lack of a reliance on phosgene. While a few homogeneous catalysts have been reported, no heterogeneous catalyst could be found in the literature for use in the synthesis of dicarbamates from diamines and dialkyl carbonates. Because heterogeneous catalysts are more manageable than homogeneous catalysts as regards separation and recycling, in our study, we hydrothermally synthesized and used pure berlinite (AlPO4) and zinc-incorporated berlinite (ZnAlPO4) as heterogeneous catalysts in the production of dimethylhexane-1,6-dicarbamate from 1,6-hexanediamine (HDA) and dimethyl carbonate (DMC). The catalysts were characterized by means of XRD, FT-IR and XPS. Various influencing factors, such as the HDA/DMC molar ratio, reaction temperature, reaction time, and ZnAlPO4/HDA ratio, were investigated systematically. The XRD characterization identified a berlinite structure associated with both the AlPO4 and ZnAlPO4 catalysts. The FT-IR result confirmed the incorporation of zinc into the berlinite framework for ZnAlPO4. The XPS measurement revealed that the zinc ions in the ZnAlPO4 structure possessed a higher binding energy than those in ZnO, and as a result, a greater electron-attracting ability. It was found that ZnAlPO4 catalyzed the formation of dimethylhexane-1,6-dicarbamate from the Methoxycarbonylation of HDA with DMC, while no activity was detected on using AlPO4. Under optimum reaction conditions (i.e. a DMC/HDA molar ratio of 8:1, reaction temperature of 349 K, reaction time of 8 h, and ZnAlPO4/HDA ratio of 5 (mg/mmol)), a yield of up to 92.5% of dimethylhexane-1,6-dicarbamate (with almost 100% conversion of HDA) was obtained. Based on these results, a possible mechanism for the Methoxycarbonylation over ZnAlPO4 was also proposed. As a heterogeneous catalyst ZnAlPO4 berlinite is highly active and selective for the Methoxycarbonylation of HDA with DMC. We propose that dimethylhexane-1,6-dicarbamate is formed via a catalytic cycle, which involves activation of the DMC by a key active intermediate species, formed from the coordination of the carbonyl oxygen with Zn(II), as well as a reaction intermediate formed from the nucleophilic attack of the amino group on the carbonyl carbon.
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Chemistry Central Journal
2007Co-Authors: Da-lei Sun, Jian-ru Deng, Zi-sheng ChaoAbstract:Research article Catalysis over zinc-incorporated berlinite (ZnAlPO 4) of the Methoxycarbonylation of 1,6-hexanediamine with dimethyl carbonate to form dimethylhexane-1,6-dicarbamat
Wei Wei - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Methoxycarbonylation of 1,6-hexamethylenediamine with methyl carbamate to dimethylhexane-1,6-dicarbamate
2016Co-Authors: Bing Han, Wen Bo Zhao, Xian Ye Qin, Wei WeiAbstract:dioxide; metal oxide; Abstract. A series of metal oxides were employed as catalysts for the synthesis of dimethylhexane-1,6-dicarbamate(HDC) from 1,6-hexamethylenediamine(HDA) and methyl carbonate(MC). Lead dioxide showed excellent catalytic activity, 100 % HDA conversion and 93 % HDC yield could be achieved at 463K for 6h. The effects of reaction temperature, reaction time and catalyst amount on the yield of HDC were investigated in details
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Catalytic Methoxycarbonylation of 1,6-Hexamethylenediamine with Methyl Carbamate to Dimethylhexane-1,6-Dicarbamate
Advanced Materials Research, 2013Co-Authors: Bing Han, Wen Bo Zhao, Xian Ye Qin, Wei WeiAbstract:A series of metal oxides were employed as catalysts for the synthesis of dimethylhexane -1,6-dicarbamate(HDC) from 1,6-hexamethylenediamine(HDA) and methyl carbonate(MC). Lead dioxide showed excellent catalytic activity, 100% HDA conversion and 93% HDC yield could be achieved at 463K for 6h. The effects of reaction temperature, reaction time and catalyst amount on the yield of HDC were investigated in details.
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Synthesis of dimethyl hexane-1,6-diyldicarbamate from 1,6-hexamethylenediamine and methyl carbamate using lead dioxide as catalyst
Catalysis Communications, 2013Co-Authors: Bing Han, Wen Bo Zhao, Xian Ye Qin, Li Yanhong, Sun Yanlin, Wei WeiAbstract:Abstract A series of metal oxides and lead compounds were employed as catalysts for the Methoxycarbonylation of 1,6-hexamethylenediamine (HDA) with methyl carbamate (MC) to produce dimethyl hexane-1,6-diyldicarbamate (HDC). Lead-containing compounds showed excellent catalytic behavior, 100% conversion of HDA and 93% yield of HDC could be achieved with lead dioxide (PbO2) as catalyst at 463 K for 6 h in the first cycle, then it goes down to 72%. The X-ray diffraction (XRD) and Infrared spectrum (IR) characterization results indicated that PbO2 catalyst has been converted into lead carbonate (PbCO3) through intermediate dilead oxide carbonate (Pb2OCO3) in the reaction process. This conversion may be the reason for the reduction of PbO2 catalytic activity.
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effective and green synthesis of methyl pyrrole 1 carboxylate with dimethyl carbonate over solid base
Catalysis Letters, 2008Co-Authors: Subing Fan, Wei Wei, Ning Zhao, Fukui Xiao, Yuhan SunAbstract:The methyl pyrrole-1-carboxylate (1-MPC) was synthesized by highly selective one-pot N-Methoxycarbonylation of pyrrole with dimethyl carbonate (DMC). Solid bases were found to be effective catalysts and the formation of 1-MPC was closely related to their basicity. The in-situ FTIR indicated that the role of solid base catalysts was to activate pyrrole via the formation of O–H bond and the weakening of N–H bond, which was attributed to the interaction between pyrrole and surface oxygen anion of solid base. Furthermore, the reaction temperature and the reactants molar ratio were found to be the main factors for the improvement of pyrrole conversion.