- Zinc-catalyzed depolymerization of polyethers to produce valuable building blocks
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The recycling of polymers continues to be a significant matter for a sustainable society. In particular, the conversion of end-of-life polymers to monomers or suitable low-molecular weight chemicals creates a feedstock for new high-quality polymeric materials and contributes to conserve resources and allow overall an efficient waste-managing system. In the present study, we have set up a straightforward methodology for the depolymerization of artificial polyethers applying cheap and abundant zinc( II) salts as precatalysts. In the presence of bio-based fatty acid chlorides as depolymerization reagent well-defined chloroesters were accessible in good to excellent yields. Moreover, acetic anhydride and fatty acids were applied as depolymerization reagents resulting in the formation of diacetates in moderate yields. In both cases the obtained products (chloroesters, diacetates) can be useful building blocks in polymerization chemistry. Noteworthy, overall a recycling of polyethers are possible. Springer Science+Business Media New York 2014.
- Enthaler, Stephan
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Read Online
- Selective Production of C2-Oxygenate Esters from Synthesis Gas using Mixed Metal Homogeneous Catalysts
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C2-Oxygenate esters, particularly ethylene glycol diacetate, may be prepared in high selectivity directly from synthesis gas in the presence of composite homogeneous catalysts which contain mixtures of ruthenium and rhodium, as major and minor components respectively, together with promoters in the form of nitrogen-containing bases or alkali metal cations, in acetic acid as solvent.
- Whyman, Robin
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Read Online
- Vicinal Glycol Esters from Synthesis Gas
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Vicinal glycol esters, such as ethylene glycol acetate esters, are prepared from synthesis gas via the use of homogeneous ruthenium catalysis.
- Knifton, John F.
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Read Online
- A Reversible Liquid-to-Liquid Organic Hydrogen Carrier System Based on Ethylene Glycol and Ethanol
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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.
- Zhou, Quan-Quan,Zou, You-Quan,Ben-David, Yehoshoa,Milstein, David
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p. 15487 - 15490
(2020/10/02)
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- Synthesis of glycol diesters through the depolymerization of polyethylene glycols with carboxylic acids using a proton-exchanged montmorillonite catalyst
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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.
- Maeno, Zen,Midogochi, Kaoru,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro
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supporting information
p. 832 - 835
(2018/02/06)
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- Effective management of polyethers through depolymerization to symmetric and unsymmetric glycol diesters using a proton-exchanged montmorillonite catalyst
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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.
- Maeno, Zen,Yamada, Shota,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro
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supporting information
p. 2612 - 2619
(2017/07/17)
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- the acidity is solidcarries ionic liquid catalyst for synthesizing ethylene glycol acetate method
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The invention discloses a method for synthesizing glycol diacetate under the catalytic action of an acidic immobilized ionic liquid. Under the catalytic action of an acidic immobilized ionic liquid, ethylene glycol and acetic acid used as raw materials are directly esterified to synthesize the glycol diacetate in a batch rectification tower, wherein the acidic immobilized ionic liquid is an acidic ionic liquid immobilized on the surface or in the pores of a support. The method has the advantages of high reaction selectivity, mild conditions, high raw material conversion rate and the like, and the catalyst can be easily separated from the reaction system and is recyclable. The glycol diacetate yield of the method can reach 99.4%, and the reaction selectivity can reach 99.5% above.
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Paragraph 0023-0028
(2017/02/24)
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- Method for synthesis of vinyl acetate
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The invention relates to a method for synthesis of vinyl acetate. The method mainly solves the problem that the existing vinyl acetate preparation method utilizing methyl acetate carbonylation and carboxide cracking has a low yield and low selectivity. The method provided through the invention comprises methyl acetate carbonylation for ethylidene diacetate preparation and ethylidene diacetate cracking for vinyl acetate preparation. A carbonylation catalyst comprises a carrier and rhodium, copper, lanthanum and lithium on the carrier. The carrier is at least one of silicon oxide and alumina. The method well solves the technical problem and can be used for vinyl acetate industrial production.
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Paragraph 0131; 0134; 0136
(2016/12/16)
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- Method for synthesizing vinyl acetate
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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.
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Paragraph 0149; 0151; 0152; 0153; 0154; 0155
(2016/12/16)
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- Synthetic method for vinyl acetate
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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.
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Paragraph 0174; 0175; 0176; 0177; 0178
(2016/12/16)
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- Production method of vinyl acetate
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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.
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Paragraph 0173; 0175; 0176; 0177; 0178; 0179
(2016/12/16)
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- Method of producing vinyl acetate from methyl acetate through hydroformylation
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The invention relates to a method of producing vinyl acetate from methyl acetate through hydroformylation 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 method herein 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 iron-series elements, at least one element from metalloid elements, and at least one metal element selected from the groups of IIB and alkali metals. The method solves the technical problems well and can be used in industrial production of the vinyl acetate.
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Paragraph 0071; 0173; 0174; 0175; 0176; 0177
(2016/12/16)
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- Method of synthesizing vinyl acetate from methyl acetate
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The invention relates to a method of synthesizing vinyl acetate from methyl acetate and mainly solves the problem 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. In the technical scheme, the method mainly 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 main catalyst and a co-catalyst, wherein the main catalyst includes a carrier and an active component, a rhodium compound being the active component, and the co-catalyst is an iodide, and the carrier is silicon dioxide which is modified by a fluorine compound and has a coating on the surface. The coating is composed of modified metal elements, and silicon dioxide adhesive which is used for bonding the modified metal elements to the surface of the carrier, wherein the modified metal elements is at least one selected from IIA metal elements.
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Paragraph 0136; 0137; 0138; 0139; 0140; 0141
(2016/12/16)
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- Method of preparing vinyl acetate from methyl acetate
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The invention relates to a method of preparing vinyl acetate from methyl 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. In the technical scheme, the method mainly 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 main catalyst and a co-catalyst, wherein the main catalyst includes a carrier and an active component, a rhodium compound being the active component, and the co-catalyst is an iodide, and the carrier is silicon dioxide which is modified by modifying metal elements and has an aluminum coating on the surface. The content of aluminum is 1.00-10.00 g/L, the content of the modifying metal elements is 0.010-1.00 g/L, and the modifying metal elements include at least one metal element in the IVB group.
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Paragraph 0157; 0158; 0159; 0160; 0161; 0162
(2016/12/16)
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- For method for producing vinyl acetate (by machine translation)
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The invention relates to a method for method for producing vinyl acetate, methyl acetate, mainly solves the carbonylation, when the cracking line preparing vinyl acetate ethylene acetate of the problem of low yield and selectivity. By using for the method for producing vinyl acetate, comprising the following steps: obtaining of carbonylation of methyl acetate-ethylene carbonate acetate; double-acetate ethylene acetate esters an ethylene cracking obtained; the the catalyst states the carbonylation SiO 2, Al 2 O 3 or mixtures thereof as a carrier, is selected from the active component comprises at least one of iron series elements, lanthanides, and IIB and alkaline earth metal selected from at least one of the technical scheme of the metal elements, better solves the technical problem of, can be used in the industrial production of ethylene acetate. (by machine translation)
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Paragraph 0182; 0183; 0184; 0185; 0186; 0187
(2016/12/16)
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- Method for producing vinyl acetate through methyl acetate carbonylation
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The invention relates to a method for producing vinyl acetate through methyl acetate carbonylation. 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 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 platinum-group elements, at least one selected from alkaline earth metals and at least one metal element selected from IVA and lanthanide-series metal elements. With the technical scheme, the technical problem is well solved. The method can be used in industrial production of vinyl acetate.
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Paragraph 0170; 0172; 0173; 0174; 0175; 0176; 0177
(2016/12/16)
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- Method for preparing vinyl acetate
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The invention relates to a method for preparing vinyl acetate. The method mainly solves the problem that the prior art for preparing vinyl acetate through methyl acetate carbonylation and carboxide cracking has a low yield and low selectivity. The method provided through the invention comprises methyl acetate carbonylation for ethylidene diacetate preparation and ethylidene diacetate cracking for vinyl acetate preparation. A carbonylation catalyst utilizes SiO2, Al2O3 or their mixture as a carrier and active ingredients comprise rhodium and at least one of cerium, strontium and tin. The method well solves the technical problem and can be used for vinyl acetate industrial production.
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Paragraph 0110; 0111; 0118; 0119
(2016/12/01)
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- Method for synthesis of vinyl acetate through hydroformylation of methyl acetate
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The invention relates to a method for synthesis of vinyl acetate through hydroformylation of methyl acetate. The method mainly solves the problem that the existing vinyl acetate preparation method utilizing methyl acetate carbonylation and carboxide cracking has a low yield and low selectivity. The method provided through the invention comprises methyl acetate carbonylation for ethylidene diacetate preparation and ethylidene diacetate cracking for vinyl acetate preparation. A carbonylation catalyst utilizes SiO2, Al2O3 or their mixture as a carrier and active ingredients comprise at least one of iron group metal elements, at least one of IIIB elements and at least one of VA and alkaline earth metals. The method well solves the technical problem and can be used for vinyl acetate industrial production.
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Paragraph 0162; 0169; 0170
(2016/12/01)
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- Conformational characteristics and configurational properties of poly(ethylene succinate) and poly(butylene succinate) and structure-property-function relationships of representative biodegradable polyesters
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Conformational characteristics and configurational properties of synthetic biodegradable polyesters, poly(ethylene succinate) and poly(butylene succinate), have been investigated by NMR experiments and molecular orbital calculations on their model compounds and the rotational isomeric state calculations for the two aliphatic polyesters. The results have been related to their crystal structures and thermal properties and compared with those obtained previously for poly((R)-3-hydroxybutyrate) and poly(lactic acid) to elucidate structureeproperty relationships of the representative biodegradable polyesters. In addition, selective affinities to degradative enzymes of the four polyesters have been satisfactorily explained in terms of their conformational characteristics and interactions with the depolymerases.
- Sasanuma, Yuji,Nonaka, Yuta,Yamaguchi, Yuki
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p. 327 - 339
(2015/03/03)
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- A simple acetylation of alcohols using ZnO nanopowder synthesized by microwave irradiation
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An efficient and selective method for acetylation of alcohols using ZnO nanopowder is described. In this method, alcohols are refluxed with a mixture of CH3COOH in the presence of catalytic amounts of ZnO nanopowder to afford their corresponding esters in good yields. This methodology is highly efficient for various structurally different alcohols: 1°, 2°, 3°. The prepared nano zinc oxide used in acetylation of alcohols which in comparison to ordinary ZnO has apparent advantages in promoting the yields of product formation.
- Javaherian, Mohammad,Sabzi, Hashem Eskandari
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p. 631 - 634
(2014/06/23)
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- Solventless acetylation of alcohols and phenols catalyzed by supported iron oxide nanoparticles
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Supported iron oxide nanoparticles on silicate catalysts were found to be efficient and easily recoverable materials in the acetylation of alcohols and phenols to their corresponding acetyl compounds using acetic anhydride under mild and solvent-less conditions. The supported iron oxide nanoparticles could be easily recovered from the reaction mixture and reused ten times without any loss in activity.
- Rajabi, Fatemeh,Luque, Rafael
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p. 129 - 132
(2014/01/06)
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- OXIDATION OF ALKANES TO ALCOHOLS
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The invention provides processes and materials for the efficient and cost- effective functionalization of alkanes, such as methane from natural gas, to provide esters, alcohols, and other compounds. The method can be used to produce liquid fuels such as methanol from a natural gas methane-containing feedstock. The soft oxidizing electrophile, a compound of a main group, post- transitional element such as Tl, Pb, Bi, and I, that reacts to activate the alkane C- H bond can be regenerated using inexpensive regenerants such as hydrogen peroxide, oxygen, halogens, nitric acid, etc. Main group compounds useful for carrying out this reaction includes haloacetate salts of metals having a pair of available oxidation states, such as Tl, Pb, Bi, and I. The inventors herein believe that a unifying feature of many of the MXn electrophiles useful in carrying out this reaction, such as Tl, Pb, and Bi species, is their isoelectronic configuration in the alkane -reactive oxidation state; the electrons having the configuation [Xe]4f145d10, with an empty 6s orbital. However, the iodine reagents have a different electronic configuration.
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Page/Page column 12; 13; 14
(2014/09/03)
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- Method of Synthesizing Polyol Acetate by Using Catalyst of Ionic Liquid Heteropoly Acid
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The present invention uses a nitrogen-containing organic compound to be reacted with an alkyl sultone to obtain a zwitterion compound. The zwitterion compound is reacted with a heteropoly acid (HPA) to obtain an ionic liquid HPA (IL-HPA). The IL-HPA is used for acetylation of polyol and HOAc for obtaining polyol acetate. The IL used in the reaction can be recycled. Thus, problems of product separation, waste acid handling, and corrosion of facilities are solved and production through esterification is improved with a green catalysis.
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Paragraph [0032]; [0039]
(2013/05/09)
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- Efficient acetylation of alcohols and phenols catalyzed by recyclable lithium bis(perfluoroalkylsulfonyl)imide
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An efficient acetylation of alcohols and phenols catalyzed by lithium bis(perfluoroalkylsulfonyl)-imide was developed. This acetylation features good yields, mild reaction condtions, and simple workup procedures. Furthermore, the catalyst bearing a long perfluoroalkyl chain is recoverable and readily reusable without losing any activity. Copyright
- Li, Guilong,Zhao, Gang
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p. 34 - 43,10
(2020/08/24)
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- Catalytic activation of carbohydrates as formaldehyde equivalents for stetter reaction with enones
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We disclose the first catalytic activation of carbohydrates as formaldehyde equivalents to generate acyl anions as one-carbon nucleophilic units for a Stetter reaction. The activation involves N-heterocyclic carbene (NHC)-catalyzed C-C bond cleavage of carbohydrates via a retro-benzoin-type process to generate the acyl anion intermediates. This Stetter reaction constitutes the first success in generating formal formaldehyde-derived acyl anions as one-carbon nucleophiles for non-self-benzoin processes. The renewable nature of carbohydrates, accessible from biomass, further highlights the practical potential of this fundamentally interesting catalytic activation.
- Zhang, Junmin,Xing, Chong,Tiwari, Bhoopendra,Chi, Yonggui Robin
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supporting information
p. 8113 - 8116
(2013/07/19)
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- Carbodeoxygenation of biomass: The carbonylation of glycerol and higher polyols to monocarboxylic acids
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Glycerol is converted to a mixture of butyric and isobutyric acid by rhodium- or iridium-catalysed carbonylation using HI as the co-catalyst. The initial reaction of glycerol with HI results in several intermediates that lead to isopropyl iodide, which upon carbonylation forms butyric and isobutyric acid. At low HI concentration, the intermediate allyl iodide undergoes carbonylation to give vinyl acetic acid and crotonic acid. Higher polyols CnH n+2(OH)n are carbonylated to the corresponding C n+1 mono-carboxylic acids. Copyright
- Coskun, Timur,Conifer, Christopher M.,Stevenson, Laura C.,Britovsek, George J. P.
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supporting information
p. 6840 - 6844
(2013/07/05)
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- Design of a highly active silver-exchanged phosphotungstic acid catalyst for glycerol esterification with acetic acid
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A series of highly active, selective, and stable silver-exchanged phosphotungstic acid (AgPW) catalysts were prepared, characterized, and evaluated for bio-derived glycerol esterification with acetic acid to produce valuable biofuel additives. The structures, morphologies, acidities, and water tolerance of these samples were determined by FTIR, Raman, XRD, SEM-EDX, FT-IR of pyridine adsorption, and H2O-TPD. Several typical acidic catalysts were also performed for comparison. Among them, partially silver-exchanged phosphotungstic acid (Ag1PW) presented exceptionally high activity, with 96.8% conversion within just 15 min of reaction time and remarkable stability, due to the unique Keggin structure, high acidity as well as outstanding water-tolerance property. A plausible reaction mechanism was also proposed. In addition, this Ag1PW catalyst exhibited universal significance for esterification, holding great potential for a wide range of other acid-catalyzed reactions.
- Zhu, Shanhui,Gao, Xiaoqing,Dong, Fang,Zhu, Yulei,Zheng, Hongyan,Li, Yongwang
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p. 155 - 163
(2013/09/02)
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- Synthesis of a novel multi-SO3H functionalized ionic liquid and its catalytic activities
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A novel multi-SO3H functionalized ionic liquid is synthesized and a detailed account of its cata- lytic activities in acetalization and acetylation is given. The results showed that the ionic liquid is very efficient in the conventional acid-catalyzed reactions with good to excellent yields within a short reaction time. Oper- ational simplicity, small amounts required, low cost of the catalyst, high yields, scalability and reusability are the key features of this methodology, which indicates the high potentialities of the novel ionic liquid to be used in environmentally friendly processes. Pleiades Publishing, Ltd., 2012.
- Xudong, Sun,Huiquan, Xiao,Yijun, Du,Jingjing, Zhang,Xuezheng, Liang,Chenze, Qi
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p. 301 - 305
(2012/10/29)
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- Novel double-SO3h functionalized ionic liquid for acetylation
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Novel double-SO3H functionalized ionic liquid (DFIL) was synthesized and its catalytic activities for acetylation studied. The result showed that the DFIL possess high acidity and was very efficient for the acetylation of alcohols, amines and phenols with good to excellent yields in short reaction times. Operational simplicity, stability to water and air, small amounts needed, low cost, high yields, high acidity, applicability to large-scale reactions and reusability are the key features of the DFIL, which indicated promising applications of DFIL in green chemical processes. Pleiades Publishing, Ltd., 2012.
- Zhu, Lili,Liang, Xuezheng
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p. 684 - 688
(2013/02/23)
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- Rational engineering of Candida antarctica lipase B for selective monoacylation of diols
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The enzyme Candida antarctica lipase B was subjected to site directed mutagenesis suggested by molecular modelling. The selectivity for the enzyme increased towards a range of diols over their corresponding monoesters as an effect of the mutations. This journal is The Royal Society of Chemistry 2012.
- Hamberg, Anders,Maurer, Steffen,Hult, Karl
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supporting information
p. 10013 - 10015
(2012/10/30)
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- Process for preparing esters and organic halides
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A process for preparing esters and organic halides, which comprises reacting - a salt having a melting point of less than 100°C (at 1 bar) and of the formula ???????? (K+)n X (COO-)n, in which K+ is an organic cation, X (COO-)n is an organic anion having an n-valent organic group X which is substituted by n carboxylate groups COO-, and n is 1, 2 or 3, - with an organic halogen compound (Hal)mY, in which Hal is a halogen atom, Y is an m-valent organic group, and m is 1, 2 or 3, to give an ester and a halide K+ Hal-.
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Page/Page column 5-7
(2013/02/27)
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- Synthesis, characterization, and biocompatibility of biodegradable hyperbranched polyglycerols from acid-cleavable ketal group functionalized initiators
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Herein we report the synthesis of biodegradable hyperbranched polyglycerols (BHPGs) having acid-cleavable core structure by anionic ring-opening multibranching polymerization (ROMBP) of glycidol using initiators bearing dimethyl and cyclohexyl ketal groups. Five different multifunctional initiators carrying one to four ketal groups and two to four hydroxyl groups per molecule were synthesized. The hydroxyl carrying initiators containing one ketal group per molecule were synthesized from ethylene glycol. An alkyne-azide click reaction was used for synthesizing initiators containing multiple cyclohexyl ketal linkages and hydroxyl groups. The synthesized BHPGs exhibited monomodal molecular weight distributions and polydispersity in the range of 1.2 to 1.6, indicating the controlled nature of the polymerizations. The polymers were relatively stable at physiological pH but degraded at acidic pH values. The polymer degradation was dependent on the type of ketal structure present in the BHPG; polymers with cyclohexyl ketal groups degraded at much slower rates than those with dimethyl ketal groups at a given pH. Good control of polymer degradation was achieved under mild acidic conditions by changing the structure of ketal linkages. A precise control of the molecular weight of the degraded HPG was achieved by controlling the number of ketal groups within the core, as revealed from the gel permeation chromatography (GPC) analyses. The decrease in the polymer molecular weights upon degradation was correlated well with the number of ketal groups in their core structure. Our data support the suggestion that glycidol was polymerized uniformly from all hydroxyl groups of the initiators. BHPGs and their degradation products were highly biocompatible, as measured by blood coagulation, complement activation, platelet activation, and cell viability assays. The controlled degradation profiles of these polymers together with their excellent biocompatibility make them suitable for drug delivery and bioconjugation applications.
- Shenoi, Rajesh A.,Lai, Benjamin F. L.,Kizhakkedathu, Jayachandran N.
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p. 3018 - 3030,13
(2020/09/02)
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- Synthesis of acetoxyacetaldehyde
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The invention belongs to the field of organic chemistry and relates to a new synthesis of acetoxyacetaldehyde comprising the steps of providing monoacetyl ethylene glycol and converting it by oxidation using an N-oxyl compound in the presence of a co-oxidant.
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Page/Page column 15
(2011/06/23)
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- Saturation vapor pressures and vaporization enthalpies of esters of ethylene glycol and lower carboxylic acids
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Saturation vapor pressures and vaporization enthalpies of ethylene glycol and C1-C5 carboxylic acid disubstituted esters of normal and branched structures are determined by the transfer method in the tem-perature range of 295 to 327 K. Dependences of vaporization enthalpies versus the number of carbon atoms in a molecule and the retention indices are determined. An analysis of existing calculation schemes is given to help predict the vaporization enthalpy of the compounds under study.
- Maslakova,Krasnykh,Levanova
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experimental part
p. 1695 - 1700
(2012/01/12)
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- Synthesis, characterization and application of poly(4-vinylpyridine)- supported Bronsted acid as reusable catalyst for acetylation reaction
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Poly(4-vinylpyridine)-supported Bronsted acids (P4VP-HX) were prepared by wet impregnation technique. These supported acids were found as efficient heterogeneous green catalysts for acetylation of alcohol, amine and phenol with different catalytic activities. The wide application of P4VP-HX as reusable solid acid catalyst in organic reactions is possible because of its simple preparation and handling, stability, simple work up procedure.
- Borah, Kalyan Jyoti,Dutta, Papia,Borah, Ruli
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experimental part
p. 225 - 228
(2011/11/06)
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- Silver triflate catalyzed acetylation of alcohols, thiols, phenols, and amines
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A variety of alcohols, thiols, phenols, and amines were subjected to acetylation reaction using acetic anhydride in the presence of catalytic quantity of silver triflate. The method described has a wide range of applications, proceeds under mild conditions, does not involve cumbersome workup, and the resulting products are obtained in high yields within a reasonable time. Georg Thieme Verlag Stuttgart · New York.
- Das, Rima,Chakraborty, Debashis
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experimental part
p. 1621 - 1625
(2011/06/25)
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- Task-oriented use of ionic liquids: Efficient acetylation of alcohols and phenols
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The ionic liquid 1-butyl-3-methylimidazolium acetate proves to be an excellent reaction medium for the acetylation of alcohols and phenols, providing better conditions than the acidic 1-butyl-3-methylimidazolium bisulfate. Reactions were carried at room temperature, with only a 10% excess of acylating agent and with no other solvent or catalyst added.
- López, Ignacio,Bravo, José Luis,Caraballo, Manuel,Barneto, José Luis,Silvero, Guadalupe
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scheme or table
p. 3339 - 3341
(2011/06/28)
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- H6GeMo10V2O40·16H 2O nanoparticles prepared by hydrothermal method: A new and reusable heteropoly acid catalyst for highly efficient acetylation of alcohols and phenols under solvent-free conditions
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A new Keggin-type heteropoly acid, namely decamolybdodivanadogermanic acid (H6GeMo10V2O40·16H 2O), with nanosized particles (5-8 nm), has been synthesized by a hydrothermal method and characterized by elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffractometry (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-Visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and potentiometric titration. H6GeMo10V2O40·16H 2O revealed high catalytic activity for acetylation of various alcohols and phenols with acetic anhydride at room temperature (298 ± 2 K) and under solvent-free conditions. The catalyst can be easily recovered and used repeatedly for five cycles with a slight loss of activity. The catalytic activity of H6GeMo10V2O40· 16H2O was higher than that of other Keggin-type heteropoly acids, such as H3PW12O40, H3PMo 12O40 and H4SiW12O40.
- Farhadi, Saeid,Zareisahamieh, Reza,Zaidi, Masoumeh
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experimental part
p. 1323 - 1332
(2012/04/04)
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- SYNTHESIS OF ACETOXYACETALDEHYDE
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The invention belongs to the field of organic chemistry and relates to a new synthesis of acetoxyacetaldehyde. Comprising the steps of providing monoacetyl ethylene glycol and converting it by oxidation using an N-oxyl compound in the presence of a co-oxidant.
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Page/Page column 23
(2011/06/23)
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- Acetylation of alcohols and phenols with acetic anhydride under solvent-free conditions using an ionic liquid based on morpholine as a recoverable and reusable catalyst
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Rapid and efficient acetylation of alcohols and phenols with acetic anhydride is performed in the presence of economical Bronsted acidic ionic liquids that bear a propanesulfonic acid group on a morpholinium cation as catalysts under solvent-free conditions. [MMPPA][HSO4] (N-methylmorpholinium propanesulfonic acid ammonium hydrogensulfate) was proven to be the most active catalyst, and after removal of water, it could be recycled and reused for up to four times without a noticeable decrease in catalytic activity. Springer-Verlag 2010.
- Yue, Caibo,Liu, Qingqing,Yi, Tingfeng,Chen, Yun
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experimental part
p. 975 - 978
(2011/09/30)
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- Spinel-type zinc aluminate (ZnAl2O4) nanoparticles prepared by the co-precipitation method: A novel, green and recyclable heterogeneous catalyst for the acetylation of amines, alcohols and phenols under solvent-free conditions
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Zinc aluminate (ZnAl2O4) nanoparticles with an average particle size of about 8 nm were easily prepared by the co-precipitation method using aqueous ammonia solution as the precipitating agent. This nanosized spinel-type oxide was characterized by TGA, XRD, FT-IR, TEM, and surface area measurement and used as the heterogeneous catalyst for the acetylation reaction. Efficient acetylation of various amines, alcohols and phenols was carried out over ZnAl2O4 nanoparticles using acetic anhydride and/or acetyl chloride as the acetylating agents at room temperature without the use of a solvent. The method is highly selective, allowing the alcoholic hydroxyl group to be protected while the phenolic hydroxyl group remains intact, and the amine group can be acetylated in the presence of the hydroxyl group. This method is fast and has a high yield. It is also clean, safe, cost effective, compatible with substrates that have other functional groups and very suitable for practical organic synthesis. In addition, the catalyst can be reused without significant loss of activity. Indeed, the catalytic activity of the ZnAl2O4 nanoparticles is higher than that of bulk ZnAl2O4.
- Farhadi, Saeid,Panahandehjoo, Somayeh
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scheme or table
p. 293 - 302
(2010/09/04)
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- Heteropolyanion-based ionic liquids: Reaction-induced self-separation catalysts for esterification
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(Figure Presented) It comes out in the wash: In the esterification of citric acid with n-butanol, heteropolyanion-based ionic liquid (IL) catalysts show high catalytic activity, self-separation, and easy reuse. The good solubility in reactants, nonmiscibility with ester product, and high melting point of the IL catalysts enable the reaction-induced switching from homogeneous (b in the picture) to heterogeneous (c) with subsequent precipitation of the catalyst (d).
- Leng, Yan,Wang, Jun,Zhu, Dunru,Ren, Xiaoqian,Ge, Hanqing,Shen, Lei
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experimental part
p. 168 - 171
(2009/04/18)
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- A heterogeneous cobalt(II) Salen complex as an efficient and reusable catalyst for acetylation of alcohols and phenols
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Acetylation of various alcohols and phenols was performed successfully using an immobilized cobalt(II) catalyst in high yield. The catalyst shows high thermal stability and was also recovered and reused at least 10 times without any considerable loss of activity.
- Rajabi, Fatemeh
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scheme or table
p. 395 - 397
(2009/05/07)
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- Simple and efficient method for acetylation of alcohols, phenols, amines, and thiols using anhydrous NiCl2 under solvent-free conditions
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Solvent-free acetylation of alcohols, phenols, amines, and thiols with acetic anhydride (Ac2O) in the presence of 0.1mol% (13mg) anhydrous NiCl2, an inexpensive and easily available catalyst, is described. Excellent yields, short reaction time, and mild reaction conditions are important features of this method.
- Meshram, Gangadhar,Patil, Vishvanath D.
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experimental part
p. 4384 - 4395
(2010/04/29)
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- A diazonium ion cascade from the nitrosation of tolazoline, an imidazoline-containing drug
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Tolazoline (1-benzylimidazoline), a representative imidazoline-containing drug, reacts readily with nitrite in acetic acid to produce a complex product mixture. Fourteen compounds have been identified as products of this transformation when an 8-fold excess of HNO2 is used. The products, which include N-nitrosoamides, esters, alcohols, and phenylacetic acid, are rationalized as arising from a cascade of reactive diazonium ions. N-Nitrosotolazoline can be isolated from the nitrosation reaction in good yield when the mixture is extracted with CH2Cl2 as the transformation progresses. It nitrosates much more rapidly (50x) than tolazoline to give, among other products, the oxime [1-(N-nitroso-2-imidazolinyl) benzylidene]hydroxylamine, which can also be produced in good yield from the reaction of tolazoline with isopropyl nitrite. At low substrate and nitrite concentrations, the main reaction products are N-nitrosotolazoline, its decomposition product N-2-hydroxyethylphenylacetamide, the above-mentioned oxime, phenyl acetic acid, and 2-hydroxyethyl phenylacetate. The tolazoline nitrosation rate in three buffer systems has been determined at pH 3.4 and 37°C (kobs = 6.25 × 10-5 s-1 in 0.5 M acetate buffer with a 10 * [NO2-] = 250 mM). Because N-nitrosotolazoline exhibits the chemical properties of a direct-acting mutagen and carcinogen, we have used the rate data to estimate its level of formation at nitrite concentrations 3 mM. Cursory examination of the nitrosation chemistry of oxymetazoline, a related drug, is primarily focused at its electron-rich aromatic ring.
- Loeppky, Richard N.,Shi, Jianzheng,Barnes, Charles L.,Geddam, Sailaja
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p. 295 - 307
(2008/12/22)
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- Al(OTf)3 as a highly efficient catalyst for the rapid acetylation of alcohols, phenols and thiophenols under solvent-free conditions
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Aluminium triflate (0.01-0.1 mol %) was found to be an efficient catalyst for the acylation of alcohols, phenols, thiols and sugars with acetic anhydride in high yields under solvent-free conditions in a short reaction time at room temperature. Racemization of optically active alcohols and epimerization of sugars were not observed. The acylation efficacy of various acyl donors was also investigated.
- Kamal, Ahmed,Khan, M. Naseer A.,Reddy, K. Srinivasa,Srikanth,Krishnaji
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p. 3813 - 3818
(2008/02/06)
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- SO42-/SnO2: Efficient, chemoselective, and reusable catalyst for acylation of alcohols, phenols, and amines at room temperature
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SO42-/SnO2 was employed for the acylation of a variety of alcohols, phenols, and amines under solvent-free conditions at room temperature. This method showed preferential selectivity for acetylation of the amino group in the presence of a hydroxyl group. The reported method is simple, mild, and environmentally viable, using several other acid anhydrides at room temperature. Copyright Taylor & Francis Group, LLC.
- Satam, Jitendra R.,Gawande, Manoj B.,Deshpande, Sameer S.,Jayaram, Radha V.
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p. 3011 - 3020
(2008/02/12)
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- Modified Marcelin-de Donder equations for the kinetics of one-and two-step reversible chemical reactions in nonideal solutions
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An approach to a unified description of the kinetics of reversible chemical reactions on both sides of the equilibrium state was suggested. The description was based on the dynamic equilibrium principle, the isotherm-isobar equation for a chemical reaction, and the volume densities of the thermodynamic activities of the reagents (normalized by the pure component states). The equations obtained were applied to describe our own and literature data on the kinetics of acid-catalyzed transesterification reaction between butyl acetate and methanol at 298 K and esterification of ethylene glycol with acetic acid at 313 K. It was shown that the observed rate constant could be represented in the form of the sum of partial contributions describing the reactions in the presence of a large excess of one of the reagents. Nauka/Interperiodica 2006.
- Povarov,Sokolova,Karpova
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p. 1874 - 1879
(2007/10/03)
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- Molecular iodine in isopropenyl acetate (IPA): a highly efficient catalyst for the acetylation of alcohols, amines and phenols under solvent free conditions
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Iodine in isopropenyl acetate (IPA) is a highly efficient catalyst for the acetylation of a variety of alcohols, phenols and amines under solvent free conditions. Primary, secondary, tertiary alcohols, amines and mono to polyhydroxy phenols and anilines with electron donating or withdrawing substituents can be easily acetylated in good to excellent yield at 85-90 °C.
- Ahmed, Naseem,van Lier, Johan E.
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p. 5345 - 5349
(2007/10/03)
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- Kinetics and quantitative structure-activity relationships for pseudomonas sp. Lipase-catalyzed hydrolysis of both monoesters and diesters of ethylene glycol
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The goal of this work is to study kinetics and quantitative structure-activity relationships for steady states of Pseudomonas sp. lipase-catalyzed hydrolysis of both diesters and monoesters of ethylene glycol. Based on the steady-state kinetics of the enzyme-catalyzed hydrolysis of the diesters of ethylene glycol, the diesters and the monoesters react simultaneously as soon as monoester has started to build up in the reaction medium. In other words, the apparent Km values of the diesters are the Km values of the diesters (KmA) plus the Km values of the monoesters (KmB), and all Vmax values are about the same. Moreover, the pH-stat titration curve of the enzyme-catalyzed hydrolysis of the diesters of ethylene glycol is initially hyperbolic, then there is a sharp falloff in the hydrolysis rate. The abrupt stoppage of the reaction (relaxation stage) may be due to the existence of two phases in the reaction medium, that is, the product (ethylene glycol) and the substrates (the diesters of ethylene glycol) are not miscible. Furthermore, quantitative structure-activity relationships for varied acyl groups of mono- and diesters of ethylene glycol are studied. The fact that both pKmA and pK mB values are linearly correlated with the hydrophobicity constant (π) but not with the electronic substituent constants (σ*) indicates that the affinity of these substrates for the enzyme depends only on the hydrophobicitv of substrates. Copyright
- Chiou, Shyh-Ying,Cheng, Yu-Ru,Lu, Chun-Ping,Lin, Yan-Fu,Lin, Long-Yau,Lin, Gialih
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p. 201 - 207
(2007/10/03)
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- A cheap, simple, and versatile method for acetylation of alcohols and phenols and selective deprotection of aromatic acetates under solvent-free condition
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Acyclic and cyclic acetates of various alcohols and phenols were obtained in excellent yields under mild reaction conditions in the presence of a catalytic amount of sodium hydroxide under solvent-free conditions and microwave irradiation. Selective deprotection of acetate group from the corresponding phenolic compounds was carried out in the presence of LiClO4· 2H2O. Copyright Taylor & Francis, Inc.
- Rajabi, Fatemeh,Saidi, Mohammad R.
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p. 483 - 491
(2007/10/03)
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- Zinc oxide (ZnO) as a new, highly efficient, and reusable catalyst for acylation of alcohols, phenols and amines under solvent free conditions
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Zinc oxide (ZnO) is a highly efficient catalyst for the acylation of a variety of alcohols, phenols and amines with acid chlorides or acid anhydrides under solvent free conditions. Primary, secondary, tertiary, allylic and benzylic alcohols, diols and phenols with electron donating or withdrawing substituents can be easily acylated in good to excellent yield.
- Hosseini Sarvari, Mona,Sharghi, Hashem
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p. 10903 - 10907
(2007/10/03)
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