27252-83-1Relevant academic research and scientific papers
ZWITTERIONIC CATALYSTS FOR (TRANS)ESTERIFICATION: APPLICATION IN FLUOROINDOLE-DERIVATIVES AND BIODIESEL SYNTHESIS
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Paragraph 0013; 0028, (2021/01/29)
An amide/iminium zwitterion catalyst has a catalyst pocket size that promotes transesterification and dehydrative esterification. The amide/iminium zwitterions are easily prepared by reacting aziridines with aminopyridines. The reaction can be applied a wide variety of esterification processes including the large-scale synthesis of biodiesel. The amide/iminium zwitterions allow the avoidance of strongly basic or acidic condition and avoidance of metal contamination in the products. Reactions are carried out at ambient or only modestly elevated temperatures. The amide/iminium zwitterion catalyst is easily recycled and reactions proceed in high to quantitative yields.
Membrane transport inspired hydrolysis of non-activated esters at near physiological pH
Mandal, Raki,Mahanty, Kingshuk,Mandal, Subhendu,De Sarkar, Suman,Tarafdar, Pradip K.
supporting information, p. 11088 - 11091 (2021/10/30)
A positively charged micelle loaded with substrates was transported selectively to the reaction site (cathode) to promote the proximity and localization of the reactants (ester and hydroxide). The guided vehicular delivery coupled with electrolysis allows the hydrolysis of non-activated esters at near physiological pH with significant yields along with recyclability.
A Reversible Liquid-to-Liquid Organic Hydrogen Carrier System Based on Ethylene Glycol and Ethanol
Zhou, Quan-Quan,Zou, You-Quan,Ben-David, Yehoshoa,Milstein, David
, p. 15487 - 15490 (2020/10/02)
Liquid organic hydrogen carriers (LOHCs) are powerful systems for the efficient unloading and loading molecular hydrogen. Herein, a liquid-to-liquid organic hydrogen carrier system based on reversible dehydrogenative coupling of ethylene glycol (EG) with ethanol catalysed by ruthenium pincer complexes is reported. Noticeable advantages of the current LOHC system is that both reactants (hydrogen-rich components) and the produced esters (hydrogen-lean components) are liquids at room temperature, and the dehydrogenation process can be performed under solvent and base-free conditions. Moreover, the hydrogenation reaction proceeds under low hydrogen pressure (5 bar), and the LOHC system has a relatively high theoretical gravimetric hydrogen storage capacity (HSC>5.0 wt %), presenting an attractive hydrogen storage system.
Amide/Iminium Zwitterionic Catalysts for (Trans)esterification: Application in Biodiesel Synthesis
Lam, Ying-Pong,Ng, Wing-Hin,Tan, Fei,Tse, Ying-Lung Steve,Wang, Xinyan,Yeung, Ying-Yeung
, p. 8083 - 8092 (2019/08/26)
A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic moiety interacting with the carbonyl substrates through nonclassical hydrogen bonding. The reaction can be applied to large-scale synthesis of biodiesel under mild conditions.
Synthesis of glycol diesters through the depolymerization of polyethylene glycols with carboxylic acids using a proton-exchanged montmorillonite catalyst
Maeno, Zen,Midogochi, Kaoru,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro
supporting information, p. 832 - 835 (2018/02/06)
A convenient and sustainable method for the synthesis of glycol diesters was developed through the depolymerization of polyethylene glycols (PEGs) with carboxylic acids using proton-exchanged montmorillonite as an efficient solid acid catalyst. Several functionalized glycol diesters were obtained in good yields from PEGs and readily available carboxylic acids. Upon reaction completion, the catalyst could be easily separated by filtration and reused with its activity remaining unchanged.
Self-assembled orthoester cryptands: Orthoester scope, post-functionalization, kinetic locking and tunable degradation kinetics
L?w, Henrik,Mena-Osteritz, Elena,Von Delius, Max
, p. 4785 - 4793 (2018/06/07)
Dynamic adaptability and biodegradability are key features of functional, 21st century host-guest systems. We have recently discovered a class of tripodal supramolecular hosts, in which two orthoesters act as constitutionally dynamic bridgeheads. Having previously demonstrated the adaptive nature of these hosts, we now report the synthesis and characterization-including eight solid state structures-of a diverse set of orthoester cages, which provides evidence for the broad scope of this new host class. With the same set of compounds, we demonstrated that the rates of orthoester exchange and hydrolysis can be tuned over a remarkably wide range, from rapid hydrolysis at pH 8 to nearly inert at pH 1, and that the Taft parameter of the orthoester substituent allows an adequate prediction of the reaction kinetics. Moreover, the synthesis of an alkyne-capped cryptand enabled the post-functionalization of orthoester cryptands by Sonogashira and CuAAC "click" reactions. The methylation of the resulting triazole furnished a cryptate that was kinetically inert towards orthoester exchange and hydrolysis at pH > 1, which is equivalent to the "turnoff" of constitutionally dynamic imines by means of reduction. These findings indicate that orthoester cages may be more broadly useful than anticipated, e.g. as drug delivery agents with precisely tunable biodegradability or, thanks to the kinetic locking strategy, as ion sensors.
Effective management of polyethers through depolymerization to symmetric and unsymmetric glycol diesters using a proton-exchanged montmorillonite catalyst
Maeno, Zen,Yamada, Shota,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro
supporting information, p. 2612 - 2619 (2017/07/17)
From the standpoint of green sustainable chemistry, it is very important to build a resource recycling system. Herein, an efficient and practical method for catalytic depolymerization of polyethers to glycol diesters was developed using proton-exchanged montmorillonite (H-mont). H-mont uniquely exhibited high catalytic activity for the depolymerization of polyethers with benzoic anhydride to symmetric glycol dibenzoates under mild reaction conditions. Various symmetric and unsymmetric glycol diesters were obtained from the reaction of diverse polyethers with carboxylic acid derivatives. The high catalytic efficiency for this depolymerization of H-mont is interpreted by its character, in which the montmorillonite layers act as an effective two-dimensional macroligand to form the intercalated complex with polyethers. Furthermore, a new protocol for the utilization of waste polyethers in water was developed based on the catalytic and adsorption abilities of H-mont.
Method for synthesizing vinyl acetate
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Paragraph 0149; 0151; 0152; 0153; 0154; 0155, (2016/12/16)
The invention relates to a method for synthesizing vinyl acetate. When vinyl acetate is prepared from methyl acetate through the route of carbonylation and cracking, vinyl acetate yield and selectivity are low. The invention mainly aims at solving the problems. The vinyl acetate synthesis method comprises the following steps: methyl acetate carbonylation is carried out, such that ethylene diacetate is obtained; and ethylene diacetate is cracked, such that vinyl acetate is obtained. A carbonylation catalyst adopts SiO2, Al2O3 or a mixture thereof as a carrier, and has active components comprising at least one selected from iron-series elements, alkaline earth metal and at least one metal element selected from IB and VA. With the technical scheme, the technical problem is well solved. The method can be used in industrial production of vinyl acetate.
Synthetic method for vinyl acetate
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Paragraph 0174; 0175; 0176; 0177; 0178, (2016/12/16)
The invention relates to a synthetic method for vinyl acetate and is mainly to solve the problems of low yield and selectivity of vinyl acetate in preparation for vinyl acetate from methyl acetate successively through carbonylation and cracking routes. According to a technical scheme of the invention, the synthetic method for vinyl acetate comprises the following steps: subjecting methyl acetate to carbonylation so as to obtain ethylidene diacetate, and subjecting ethylidene diacetate to cracking so as to obtain vinyl acetate, wherein a carbonylation catalyst uses SiO2, Al2O3 or a mixture of SiO2 and Al2O3 as a carrier; an active component is at least one selected from the group consisting of platinum-cluster metals, at least one selected from the group consisting of group-VIB metals, and at least one selected from the group consisting of group-IB metals and lanthanide series metals; thus, the above-mentioned technical problems are well solved, and the synthetic method can be applied in industrial production of vinyl acetate.
Production method of vinyl acetate
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Paragraph 0173; 0175; 0176; 0177; 0178; 0179, (2016/12/16)
The invention relates to a production method of vinyl acetate and mainly solves the problems of low yield and low selectivity of the vinyl acetate when methyl acetate is successively subjected to carbonylation and pyrolysis to prepare the vinyl acetate. The production method includes the following steps: 1) carbonylating the methyl acetate to obtain ethylidene diacetate; and 2) pyrolyzing the ethylidene diacetate to obtain the vinyl acetate. A carbonylation catalyst includes a carrier being formed from SiO2, Al2O3 or a mixture of them, and an active component including at least one of platinum-series elements, at least one element from metalloid elements, and at least one metal element from the groups of IIB and lanthanide-series metals. The method solves the technical problems well and can be used in industrial production of the vinyl acetate.
