- Reactions of π-allylic complexes of palladium with methyl formate
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The reaction of methyl formate with various π-allylic palladium complexes is reported. Unsaturated carboxylic acid esters are formed in high yield and selectivity. A comparison of the reactivity of methyl formate with that of the hydroesterification subst
- Keim,Becker,Kraneburg,Greven
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- Palladium-Catalyzed Methoxycarbonylation of 1,3-Butadiene to Methyl-3-Pentenoate: Introduction of a Continuous Process
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The base-assisted Pd(cod)Cl2/Xantphos-catalyzed methoxycarbonylation of 1,3-butadiene (BD) to methyl-3-pentenoate (MP) was explored. Mechanistic studies suggest the excessive Xantphos (beyond an equimolar amount per Pd) as well as its substitute, pyridines of proper steric and electronic functionality, do participate the catalytic cycle and significantly reduce the activation energy by accelerating the rate-limiting methanolysis step. As thus, all the reaction parameters, especially the solvents, were optimized based on the Pd(cod)Cl2/Xantphos/4-hexylpyridine catalytic system, enabling the construction of a continuous process. Systematic optimization demonstrates that a yield of 82% of MP with a purity of 99.8% could be reached under steady-state operation.
- Han, Li-Jun,Ma, Shuang-Shuang,Rao, Chong-Shun,Sheng, Gui-Yang,Xu, Bao-Hua,Zhang, Jun-Ping
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p. 283 - 290
(2021/10/27)
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- Selecting double bond positions with a single cation-responsive iridium olefin isomerization catalyst
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The catalytic transposition of double bonds holds promise as an ideal route to alkenes of value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, normally requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst selectively produces either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na+, mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized 1-butenes, providing insight into strategies for catalyst development based on noncovalent modifications.
- Camp, Andrew M.,Kita, Matthew R.,Blackburn, P. Thomas,Dodge, Henry M.,Chen, Chun-Hsing,Miller, Alexander J.M.
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supporting information
p. 2792 - 2800
(2021/03/01)
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- Directing Selectivity to Aldehydes, Alcohols, or Esters with Diphobane Ligands in Pd-Catalyzed Alkene Carbonylations
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Phenylene-bridged diphobane ligands with different substituents (CF3, H, OMe, (OMe)2, tBu) have been synthesized and applied as ligands in palladium-catalyzed carbonylation reactions of various alkenes. The performance of these ligands in terms of selectivity in hydroformylation versus alkoxycarbonylation has been studied using 1-hexene, 1-octene, and methyl pentenoates as substrates, and the results have been compared with the ethylene-bridged diphobane ligand (BCOPE). Hydroformylation of 1-octene in the protic solvent 2-ethyl hexanol results in a competition between hydroformylation and alkoxycarbonylation, whereby the phenylene-bridged ligands, in particular, the trifluoromethylphenylene-bridged diphobane L1 with an electron-withdrawing substituent, lead to ester products via alkoxycarbonylation, whereas BCOPE gives predominantly alcohol products (n-nonanol and isomers) via reductive hydroformylation. The preference of BCOPE for reductive hydroformylation is also seen in the hydroformylation of 1-hexene in diglyme as the solvent, producing heptanol as the major product, whereas phenylene-bridged ligands show much lower activities in this case. The phenylene-bridged ligands show excellent performance in the methoxycarbonylation of 1-octene to methyl nonanoate, significantly better than BCOPE, the opposite trend seen in hydroformylation activity with these ligands. Studies on the hydroformylation of functionalized alkenes such as 4-methyl pentenoate with phenylene-bridged ligands versus BCOPE showed that also in this case, BCOPE directs product selectivity toward alcohols, while phenylene-bridge diphobane L2 favors aldehyde formation. In addition to ligand effects, product selectivities are also determined by the nature and the amount of the acid cocatalyst used, which can affect substrate and aldehyde hydrogenation as well as double bond isomerization.
- Aitipamula, Srinivasulu,Britovsek, George J. P.,Nobbs, James D.,Tay, Dillon W. P.,Van Meurs, Martin
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p. 1914 - 1925
(2021/06/28)
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- Method for enhancing long-chain olefin hydrogen esterification reaction by ionic liquid
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The invention relates to a method for preparing carboxylic ester through long-chain olefin hydrogen esterification reaction. The method is characterized by comprising the following steps: mixing long-chain olefin of which the C number is greater than or equal to 4 with a catalyst, a carbonyl source and alkyl alcohol according to a certain ratio, and carrying out hydrogen esterification reaction in a high-boiling-point solvent such as ester, ketone, ether, amide, aromatic hydrocarbon, sulfone (sulfoxide) or conventional ionic liquid. The first ligand is a bidentate phosphine ligand, and the second ligand is an ionic liquid containing a single-coordination central atom (N, P). The method has the advantages that raw material gas and liquid phases can be in full contact, the catalyst and a high-boiling-point solvent system can be recycled, and rapid separation of the catalyst and a product is achieved. In the conjugated olefin hydrogen esterification reaction, the olefin conversion rate is more than 80%, and the product selectivity is more than 85%; in the monoolefine hydrogen esterification reaction, the olefin conversion rate is greater than 90%, and the product selectivity is greater than 95%.
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Paragraph 0039-0064
(2021/06/13)
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- Modulation of N^N′-bidentate chelating pyridyl-pyridylidene amide ligands offers mechanistic insights into Pd-catalysed ethylene/methyl acrylate copolymerisation
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The efficient copolymerisation of functionalised olefins with alkenes continues to offer considerable challenges to catalyst design. Based on recent work using palladium complexes containing a dissymmetric N^N′-bidentate pyridyl-PYA ligand (PYA = pyridylidene amide), which showed a high propensity to insert methyl acrylate, we have here modified this catalyst structure by inserting shielding groups either into the pyridyl fragment, or the PYA unit, or both to avoid fast β-hydrogen elimination. While a phenyl substituent at the pyridyl side impedes catalytic activity completely and leads to an off-cycle cyclometallation, the introduction of an ortho-methyl group on the PYA side of the N^N′-ligand was more prolific and doubled the catalytic productivity. Mechanistic investigations with this ligand system indicated the stabilisation of a 4-membered metallacycle intermediate at room temperature, which has previously been postulated and detected only at 173 K, but never observed at ambient temperature so far. This intermediate was characterised by solution NMR spectroscopy and rationalises, in part, the formation of α,β-unsaturated esters under catalytic conditions, thus providing useful principles for optimised catalyst design.
- ó Máille, Gearóid M.,Albrecht, Martin,Dall'Anese, Anna,Grossenbacher, Philipp,Milani, Barbara,Montini, Tiziano
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p. 6133 - 6145
(2021/05/19)
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- Probing the Mechanism of Photoaffinity Labeling by Dialkyldiazirines through Bioorthogonal Capture of Diazoalkanes
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Dialkyldiazirines have emerged as reagents of choice for biological photoaffinity labeling studies. The mechanism of crosslinking has dramatic consequences for biological applications where instantaneous labeling is desirable, as carbene insertions display different chemoselectivity and are much faster than competing mechanisms involving diazo or ylide intermediates. Here, deuterium labeling and diazo compound trapping experiments are employed to demonstrate that both carbene and diazo mechanisms operate in the reactions of a dialkyldiazirine motif that is commonly utilized for biological applications. For the fraction of intermolecular labeling that does involve a carbene mechanism, direct insertion is not necessarily involved, as products derived from a carbonyl ylide are also observed. We demonstrate that a strained cycloalkyne can intercept diazo compound intermediates and serve as a bioorthogonal probe for studying the contribution of the diazonium mechanism of photoaffinity labeling on a model protein under aqueous conditions.
- Am Ende, Christopher W.,Asare-Okai, Papa Nii,Fox, Joseph M.,Jemas, Andrew,O'brien, Jessica G. K.
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supporting information
p. 9415 - 9420
(2020/12/21)
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- Regioselective Isomerization of Terminal Alkenes Catalyzed by a PC(sp3)Pincer Complex with a Hemilabile Pendant Arm
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We describe an efficient protocol for the regioselective isomerization of terminal alkenes employing a previously described bifunctional Ir-based PC(sp3)complex (4) possessing a hemilabile sidearm. The isomerization, catalyzed by 4, results in a one-step shift of the double bond in good to excellent selectivity, and good yield. Our mechanistic studies revealed that the reaction is driven by the stepwise migratory insertion of Ir?H species into the terminal double bond/β-H elimination events. However, the selectivity of the reaction is controlled by dissociation of the hemilabile sidearm, which acts as a selector, favoring less sterically hindered substrates such as terminal alkenes; importantly, it prevents recombination and further isomerization of the internal ones.
- De-Botton, Sophie,Filippov, D.Sc. Oleg A.,Shubina, Elena S.,Belkova, Natalia V.,Gelman, Dmitri
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p. 5959 - 5965
(2020/10/15)
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- Nylon Intermediates from Bio-Based Levulinic Acid
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Use of ZrO2/SiO2 as a solid acid catalyst in the ring-opening of biobased γ-valerolactone with methanol in the gas phase leads to mixtures of methyl 2-, 3-, and 4-pentenoate (MP) in over 95 % selectivity, containing a surprising 81 % of M4P. This process allows the application of a selective hydroformylation to this mixture to convert M4P into methyl 5-formyl-valerate (M5FV) with 90 % selectivity. The other isomers remain unreacted. Reductive amination of M5FV and ring-closure to ?-caprolactam in excellent yield had been reported before. The remaining mixture of 2- and 3-MP was subjected to an isomerising methoxycarbonylation to dimethyl adipate in 91 % yield.
- Marckwordt, Annemarie,El Ouahabi, Fatima,Amani, Hadis,Tin, Sergey,Kalevaru, Narayana V.,Kamer, Paul C. J.,Wohlrab, Sebastian,de Vries, Johannes G.
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supporting information
p. 3486 - 3490
(2019/02/13)
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- METHOD FOR PRODUCING PENTENOIC ACID ESTER
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PROBLEM TO BE SOLVED: To provide a production method capable of obtaining a pentenoic acid ester in high yield even without using a large amount of alcohol while suppressing by-production of an ether. SOLUTION: There is provided a method for producing a pentenoic acid ester, which comprises a step of synthesizing a pentenoic acid ester containing at least one selected from the group consisting of formulas (2), (3) and (4) by bringing γ-valerolactone and an alcohol of the formula (1) into contact with each other in the presence of a catalyst containing X type zeolite. [In the formula (1), R represents an alkyl group having 1 to 6 carbon atoms. In the formulas (2), (3) and (4), R represents an alkyl group having 1 to 6 carbon atoms]. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
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Paragraph 0041; 0042; 0043; 0048; 0051; 0052
(2019/01/19)
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- Catalytic Regio- and Enantioselective Oxytrifluoromethylthiolation of Aliphatic Internal Alkenes by Neighboring Group Assistance
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Chiral selenide-catalyzed oxytrifluoromethylthiolation of aliphatic internal alkenes by a formally intermolecular strategy is disclosed, affording CF3S 1,3-amino alcohol and 1,3-diol derivatives with high regio-, enantio-, and diastereoselectivities. The reactions are promoted by a neighboring imide or ester group on substrates via a six-membered ring transition state. This assistance strategy is also successfully applied to the regio- and diastereoselective oxyhalofunctionalization of internal alkenes and the conversion of alkynes.
- Xu, Jia,Zhang, Yuanyuan,Qin, Tian,Zhao, Xiaodan
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supporting information
p. 6384 - 6388
(2018/10/09)
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- Olefin Dimerization and Isomerization Catalyzed by Pyridylidene Amide Palladium Complexes
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A series of cationic palladium complexes [Pd(N^N′)Me(NCMe)]+ was synthesized, comprising three different N^N′-bidentate coordinating pyridyl-pyridylidene amide (PYA) ligands with different electronic and structural properties depending on the PYA position (o-, m-, and p-PYA). Structural investigation in solution revealed cis/trans isomeric ratios that correlate with the donor properties of the PYA ligand, with the highest cis ratios for the complex having the most donating o-PYA ligand and lowest ratios for that with the weakest donor p-PYA system. The catalytic activity of the cationic complexes [Pd(N^N′)Me(NCMe)]+ in alkene insertion and dimerization showed a strong correlation with the ligand setting. While complexes bearing more electron donating m- and o-PYA ligands produced butenes within 60 and 30 min, respectively, the p-PYA complex was much slower and only reached 50% conversion of ethylene within 2 h. Likewise, insertion of methyl acrylate as a polar monomer was more efficient with stronger donor PYA units, reaching a 32% ratio of methyl acrylate vs ethylene insertion. Mechanistic investigations about the ethylene insertion allowed detection, for the first time, by NMR spectroscopy both cis- and trans-Pd-ethyl intermediates and, furthermore, revealed a trans to cis isomerization of the Pd-ethyl resting state as the rate-limiting step for inducing ethylene conversion. These PYA palladium complexes induce rapid double-bond isomerization of terminal to internal alkenes through a chain-walking process, which prevents both polymerization and also the conversion of higher olefins, leading selectively to ethylene dimerization.
- Navarro, Miquel,Rosar, Vera,Montini, Tiziano,Milani, Barbara,Albrecht, Martin
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p. 3619 - 3630
(2018/10/05)
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- Selective Production of Terminally Unsaturated Methyl Esters from Lactones Over Metal Oxide Catalysts
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Metal oxide catalysts were studied for their selectivity for the production of a terminally unsaturated methyl ester, methyl 5-hexenoate (M5H), from a 6 carbon, 6-membered ring lactone, δ-hexalactone (DHL). A 15?wt% Cs/SiO2 catalyst had a selectivity of 55% to M5H. This selectivity was the highest of the metal oxide catalysts studied, which were Cs/SiO2, MgO, SrO, CeO2, ZrO2, Ta2O5, MgAl2O4, and a Mg–Zr mixed oxide. The Cs/SiO2 catalyst was utilized for the ring-opening of γ-valerolactone (GVL), a 5 carbon, 5-membered ring lactone. The catalyst was 88% selective to the terminally unsaturated methyl ester, methyl 4-pentenoate (M4P). Weight hourly space velocity studies determined that the unsaturated ester distributions remained constant and no C=C double bond isomerization occurred. Liquid phase transesterification reactions with DHL and methanol and nuclear magnetic resonance spectroscopy confirmed that DHL undergoes ring-opening transesterification to produce an?ω-1 hydroxy methyl ester, methyl 5-hydroxyhexanoate (M5HH). Liquid phase transesterification reactions and thermochemistry calculations established that the equilibrium for GVL transesterification with methanol was favored towards the ring-closed lactone instead of the ring-opened hydroxy ester because of the decreased ring strain of GVL compared to DHL. The difference in terminally unsaturated methyl ester selectivity between GVL and DHL manifests from the difference in ring-strain energy. DHL passes through the M5HH intermediate as a result of greater ring strain, while the production of M4P from GVL most likely occurs through a direct, concerted mechanism. Graphical Abstract: [Figure not available: see fulltext.].
- Brentzel, Zachary J.,Ball, Madelyn R.,Dumesic, James A.
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p. 3072 - 3081
(2018/08/22)
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- Isomerizing Methoxycarbonylation of Alkenes to Esters Using a Bis(phosphorinone)xylene Palladium Catalyst
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The synthesis and characterization of bulky diphosphine 1,2-bis(4-phosphorinone)xylene, BPX, and its palladium complexes [(BPX)PdCl2] and [(BPX)Pd(O2CCF3)2] are described. BPX was evaluated as a ligand in Pd-catalyzed isomerizing methoxycarbonylation. A broad range of alkenes, including terminal, internal, branched, and functionalized alkenes, can be converted to esters with activities and selectivities matching or surpassing the performance of the state-of-the-art palladium bis(di(tert-butyl)phosphino-o-xylene (Pd-DTBPX) catalyst. A molecular structure of the precatalyst [(BPX)Pd(O2CCF3)2] was obtained showing a square planar geometry and a bite angle of 100.11(3)°. Rhodium carbonyl complexes [(BPX)Rh(CO)Cl] and [(DTBPX)Rh(CO)Cl] were synthesized to compare the relative electronic parameters, revealing a ν(C≡O) of 1956.8 and 1948.3 cm-1, respectively, suggesting a reduced ability of BPX to donate electron density to the metal relative to DTBPX. Competitive protonation experiments between BPX and DTBPX in the presence of CH3SO3H exclusively produce [DTBPX(H)2]2+, providing additional evidence that BPX is a much weaker base than DTBPX. This could be due to either the effect of the electron-withdrawing ketone group in the phosphorinone ring or the compression of the C-P-C bond angle induced by the ring structure. The 31P NMR (CDCl3) chemical shift of BPX is 5.6 ppm, upfield of DTBPX at 27.6 ppm. This anomalous result is attributed to a strong gamma substituent effect of C=O in the BPX ligand. The improved activity of Pd-BPX, relative to Pd-DTBPX, could be attributed to a more electrophilic PdII center, which could accelerate the rate-determining methanolysis step.
- Nobbs, James D.,Low, Choon Heng,Stubbs, Ludger P.,Wang, Cun,Drent, Eite,Van Meurs, Martin
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supporting information
p. 391 - 398
(2017/04/26)
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- Efficient and sustainable transformation of gamma-valerolactone into nylon monomers
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Herein, we reported the facile synthesis of dicarboxylic esters from biomass derived gamma-valerolactone (GVL) aiming for nylon monomer preparation via a novel synthetic route which improved the efficiency and overcame the need for toxic carbon monoxide for the synthesis of dicarboxylic esters from GVL.
- Yang, Yong,Wei, Xurui,Zeng, Fanxin,Deng, Li
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supporting information
p. 691 - 694
(2016/02/12)
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- Ligand-Controlled Palladium-Catalyzed Alkoxycarbonylation of Allenes: Regioselective Synthesis of α,β- and β,γ-Unsaturated Esters
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The palladium-catalyzed regioselective alkoxycarbonylation of allenes with aliphatic alcohols allows to produce synthetically useful α,β- and β,γ-unsaturated esters in good yields. Efficient selectivity control is achieved in the presence of appropriate ligands. Using Xantphos as the ligand, β,γ-unsaturated esters are produced selectively in good yields. In contrast, the corresponding α,β-unsaturated esters are obtained with high regioselectivity in the presence of PPh2Py as the ligand. Preliminary mechanistic studies revealed that these two catalytic processes proceed by different reaction pathways. In addition, this novel protocol was successfully applied to convert an industrially available bulk chemical, 1,2-butadiene, into dimethyl adipate, which is a valuable feedstock for polymer and plasticizer syntheses, with high yield and TON (turnover number).
- Liu, Jie,Liu, Qiang,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 8556 - 8563
(2015/07/15)
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- Methyl 4-methoxypentanoate: A novel and potential downstream chemical of biomass derived gamma-valerolactone
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Lignocellulosic derived gamma-valerolactone was effectively converted into methyl 4-methoxypentanoate, a potential liquid biofuel, solvent and fragrance, by the catalysis of a hydrogen exchanged ultra-stable Y zeolite (HUSY) and insoluble carbonates such as CaCO3. The catalytic competing generation process between methyl 4-methoxypentanoate and pentenoate esters was also analysed.
- Li, Zheng,Jiang, Yetao,Tang, Xing,Zuo, Miao,Zeng, Xianhai,Sun, Yong,Lin, Lu
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p. 8297 - 8300
(2015/03/05)
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- PROCESS TO PREPARE EPSILON-CAPROLACTAM
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The invention is directed to a process to prepare ε-caprolactam and/or unsaturated ε-caprolactam from a pentenamide by contacting the pentenamide with a mixture of hydrogen and carbon monoxide in the presence of a solvent and a catalyst system comprising of a Group 8-10 metal and a phosphorus-donor ligand. The ligand may be a xantphos-type ligand.
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Page/Page column 12
(2014/10/18)
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- Palladium-catalyzed alkoxycarbonylation of conjugated dienes under acid-free conditions: Atom-economic synthesis of β,γ-unsaturated esters
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Carbonylation reactions constitute important methodologies for the synthesis of all kinds of carboxylic acid derivatives. The development of novel and better catalysts for these transformations is of interest for both academic and industrial research. Here, a benign palladium-based catalyst system for the alkoxycarbonylation of conjugated dienes under acid-free conditions has been developed. This atom-efficient transformation provides straightforward access to a variety of β,γ-unsaturated esters in good to excellent yields and often with high selectivities. As an industrially relevant example the (formal) synthesis of dimethyl adipate and ε-caprolactam from 1,3-butadiene is demonstrated.
- Fang, Xianjie,Li, Haoquan,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 9030 - 9034
(2014/09/17)
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- METHOD OF MANUFACTURE OF OCTANEDIOIC ACID, PRECURSORS, AND DERIVATIVES
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A method for the manufacture of 1,8-octanedioic acid comprises: reacting gamma-valerolactone with an alcohol in the presence of an acid or a base catalyst to provide an alkyl pentenoate, converting the alkyl pentenoate in the presence of a metathesis initiator to provide the dialkyl octenedioate, reacting the dialkyl octenedioate with hydrogen in the presence of a hydrogenation catalyst to provide a dialkyl 1,8-octanedioate and hydrolyzing the dialkyl 1,8-octanedioate to provide the 1,8-octanedioic acid.
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Paragraph 0080; 0081
(2014/10/04)
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- PROCESS FOR THE PREPARATION OF FORMYLVALERIC ACID AND ADIPIC ACID
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The invention relates to a process for the production of 5-formylvaleric acid and adipic acid or esters thereof from an isomeric mixture of pentenoic acid or esters thereof said mixture comprising at least 4-pentenoic acid or esters thereof, and further comprising 3-pentenoic acid and/or 2-pentenoic acid or esters thereof, theprocess comprising: (a) subjecting the isomeric mixture of pentenoic acid to a hydroformylation reaction comprising a hydroformylation catalyst which is non-isomerizing towards the pentenoic acid or esters thereof to obtain a mixture comprising 5-formylvaleric acid or esters thereof and further comprising 3-pentenoic acid and/or 2-pentenoic acid, or esters thereof; (b) separating the 3-pentenoic acid and/or 2-pentenoic acid, or esters thereof from the 5-formylvaleric acid or esters thereof; (c) subjecting the separated pentenoic acids or esters thereof to a carbonylation reaction comprising an isomerizing carbonylation catalyst to obtain adipic acid or esters thereof; (d) optionally isolating the adipic acid or ester thereof; and (e) optionally isolating the separated 5-formylvaleric acid or esters thereof. The process allows for efficient production of two different intermediates for producing polyamide using a single process, with good selectivity, little waste, in an economically efficient fashion. The process is very suitable to use an isomeric pentenoic acid mixture obtained from valerolactone, and can be used to produce renewable polyamide intermediates using a single process.
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Page/Page column 7
(2014/08/06)
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- Ionic-liquid-catalyzed efficient transformation of γ-valerolactone to methyl 3-pentenoate under mild conditions
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Green nylons! Acidic ionic-liquid catalysis for the transformation of g-valerolactone into methyl 3-pentenoate (M3P) is shown to be performed efficiently under mild conditions. M3P is obtained selectively from a reaction at 1708C for 3.5 h in the presence of an acidic ionic liquid that has a low vapor pressure, high thermal stability, and excellent catalytic performance. A possible reaction pathway for this conversion is also presented.
- Zeng, Fan-Xin,Liu, Hai-Feng,Deng, Li,Liao, Bing,Pang, Hao,Guo, Qing-Xiang
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p. 600 - 603
(2013/07/27)
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- PROCESS TO PRODUCE ALKENOIC ACID ESTERS FROM LACTONES
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This invention relates to a process for the preparation of alkenoic acid esters comprising contacting a lactone with an alcohol and an acidic heterogeneous catalyst, characterised in that the process is carried out in the presence of at least 20 ppm of an acid having a pKa of 5 or less, relative to the amount of the lactone. The presence of at least 20 ppm of an acid having a pKa of 5 or less may stabilise the catalyst during the reaction and may also be used for reactivating an acidic heterogeneous catalyst. The improved yield advantageously allows energy conservation.
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Page/Page column 0052; 0053; 0054; 0055; 0056
(2013/06/28)
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- Towards 'bio-based' Nylon: Conversion of γ-valerolactone to methyl pentenoate under catalytic distillation conditions
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Methyl pentenoate, a promising Nylon intermediate, is produced in >95% yield via the transesterification of γ-valerolactone, a bio-based intermediate, under catalytic distillation conditions. The Royal Society of Chemistry.
- Lange, Jean-Paul,Vestering, Jan Z.,Haan, Rene J.
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p. 3488 - 3490
(2008/03/12)
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- A PROCESS FOR THE PREPARATION OF AN ALKYL ALKENOATE
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A process for the preparation of an alkyl alkenoate, wherein a lactone of the general molecular formula (I) wherein n is 1, 2 or 3, R1 is a C1-C4 alkyl group, and R2, R3 and R4 are, independently, a H atom or a C1-C4 alkyl group, is reacted with a C1-C4 alkyl alcohol in a liquid phase in the presence of a strong acid catalyst at transesterification conditions to form the alkyl alkenoate, wherein alkyl alkenoate and alcohol are continuously removed from the liquid phase by distillation.
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Page/Page column 11-14
(2008/06/13)
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- Synthesis of alkenoate esters from lactones and alcohols
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The invention relates to the synthesis of alkenoate esters from a corresponding lactone and an alcohol in the presence of a basic catalyst. More specifically, this invention relates to the synthesis of methyl-4-pentenoate ester from 5-methyl butyrolactone and methanol.
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- Process for the preparation of a caprolactam precursor from butadiene
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The invention relates to a process for the preparation of a caprolactam precursor starting from butadiene, whereby the process comprises a step in which butadiene is hydroformylated into a mixture of pentenals in the presence of carbon monoxide, hydrogen and a hydroformylation catalyst. The invention also relates to a process in which butadiene is hydroformylated in the presence of an alcohol resulting in a reaction mixture comprising an acetal of pentenals. The invention further relates to the preparation of methyl-3-pentenoate by oxidizing a pentenal and/or an acetal of pentenal containing reaction mixture.
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- Electrochemical reduction of CO2 in the presence of 1,3-butadiene using a hydrogen anode in a nonaqueous medium
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The possibility or anodic generation of a solvated proton on gas-diffusion electrode in an aprotic medium in the presence of carbon dioxide and 1,3-butadiene has been demonstrated. Formic acid was shown to be the only product of the reaction in the initially approtic medium with the use of a hydrogen gas-diffusion anode. The influence of the counterion on the reactivity of the CO2*- radical anion in electrocarboxylation was shown experimentally.
- Grinberg, V. A.,Koch, T. A.,Mazin, V. M.,Mysov, E. I.,Sterlin, S. R.
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p. 294 - 299
(2007/10/03)
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- Processes and catalyst compositions for hydrocyanation of monoolefins
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Processes for hydrocyanation of nonconjugated acyclic aliphatic monoolefins, monoolefins conjugated to an ester group, or monoolefins conjugated to a nitrile group which utilize a catalyst precursor composition comprising a bidentate phosphite ligand and zero-valent nickel preferably in the presence of a Lewis acid prompter. Catalyst precursor compositions are also disclosed.
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- Stereochemical consequences in the deprotonation of enoates
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A cyclic transition structure for the deprotonation of enoates was proposed to rationalize the geometry of the deconjugated olefin and the substrate reactivity patterns.
- Galatsis, Paul,Manwell, Jeffrey J.,Millan, Scott D.
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p. 5261 - 5264
(2007/10/03)
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- Cobalt-Catalyzed Photochemical Carbonylation of Allylic Amines
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Allylic amines are carbonylated at room temperature in the presence of cobalt catalysts under UV irradiation.With allylamine, 2-pyrrolidone, N,N'-diallylurea, and N-allyl-3-butenamide were obtained.The photochemical cleavage of C-N bond of amines coordinated to cobalt metals was suggested.
- Mori, Sadayuki,Matsuyoshi, Hiroaki,Kudo, Kiyoshi,Sugita, Nobuyuki
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p. 1397 - 1400
(2007/10/02)
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- Maximally Inhibited Pyrolysis Kinetcs of Bromo Esters in the Gas Phase. The Ion Pair Mechanism
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The kinetics of the pyrolyses of two bromo esters have been investigated in a static system over the temperature range 379-419 deg C and pressure range 51-110 Torr.The reactions in seasoned vessels, and under maximum inhibition with the radical chain suppressor propene, are homogeneous, unimolecular, and follow a first-order rate law.The Arrhenius equations for these elimination processes were found to be as follows: for methyl 4-bromobutyrate, log k1 (s-1) = (13.38 +/- 0.59) - (216.7 +/- 7.6)kJ mol-1 (2.303RT)-1; for methyl 5-bromovalerate, log k1 (s-1) = (13.83 +/- 0.17) - (228.9 +/- 2.3) kJ mol-1 (2.303RT)-1.The anchimeric assistante of the carbomethoxy substituent is determinant in the elimination process, where dehydrobromination product and lactone formation result from an intimate ion pair type of mechanism.The partial rates toward each of the primary products have been determined, reported, and discussed.The present work provides further support of the intimate ion pair mechanism in the gas-phase pyrolysis of special types of organic halides.
- Chuchani, Gabriel,Dominguez, Rosa M.
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p. 1883 - 1887
(2007/10/02)
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- CC-KUPLUNGEN VON CO2 MIT 1,3-DIENEN AN EISEN(0)-KOMPLEXEN; CARBOXYLATBILDUNG UND FOLGEREAKTIONEN
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1,3-Dienes react with CO2 at ligand-iron(0) systems to η3-allyl carboxylates.The dynamic allylic system is influenced by addition of further ligands such as phosphanes or maleic acid anhydride or acetic acid anhydride.The direction of this infl
- Hoberg, Heinz,Jenni, Klaus
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p. 193 - 202
(2007/10/02)
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- C-C-VERKNUEPFUNG VON ALKENEN MIT CO2 AN NICKEL(0); n-PENTENSAEUREN AUS ETHEN
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Ethene undergoes oxidative coupling reactions with CO2 and (Lig)Ni0 systems to give oxanickela complexes.Under suitable conditions depending on the temperature and ethene pressure, isomers of pentenoic acid are formed in high yield.
- Hoberg, Heinz,Peres, Yolande,Milchereit, Armin
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p. C41 - C43
(2007/10/02)
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- Lithium/Ammonia Reductions of 2-Thiophenecarboxylic Acids
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Lithium/ammonia reductions of 2-thiophenecarboxylic acids (1) in the absence of a proton source afforded mixtures of products.In the presence of methanol acyclic mercapto carboxylic acids (4) were the major products.Ring closure of 4 to the corresponding thiolactones (12) showed the double bonds in 4 to be of cis geometry.Attempts were made to prepare Z olefinic compounds derived from these mercapto carboxylic acids.Lithium 2-thiophenecarboxylate salts (2) afforded good yields of the corresponding 2,5-dihydro-2-thiophenecarboxylic acids (3).The presence of substituents on the ring and the ratio of metal to acid were significant factors in determining the nature of this products.A mechanism is proposed to explain the products observed.
- Blenderman, Walter G.,Joullie, Madeleine M.,Preti, George
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p. 3206 - 3213
(2007/10/02)
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- Double Bond Stabilizing Abilities of Formyl, Carbo-tert-butoxy, and Carbomethoxy Substituents
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Equilibrium constants for reactions of the type trans-MeCH=CHCH2COX trans-EtCH=CHCOX, where X is H, OMe, and O-t-Bu, have been determined in tert-butyl alcohol solution at various temperatures by using basic catalysts.These equilibrium constants for formation of the conjugated isomer, extrapolated to 25 deg C, are 24, 4.9, and 5.1 for the aldehyde, methyl ester, and tert-butyl ester, respectively.Possible explanations for the relative magnitudes of these equilibrium constants are discussed.
- Hine, Jack,Kanagasabapathy, V.M.,Ng, Peter
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p. 2745 - 2748
(2007/10/02)
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