- Reactions of methoxycarbonylcarbene with 3-ethyl-2-phenyl- and 2,3-diphenyloxazolidines
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The reactions of methoxycarbonylcarbene, which was generated by catalytic thermal decomposition of methyl diazoacetate, with 3-ethyl-2-phenyl- or 2,3-diphenyloxazolidines resulted in the insertion of the former predominantly at the C - N bond of the oxazo
- Molchanov,Stepakov,Kopf,Zenkevich,Kostikov
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- Long-lived 1H nuclear spin singlet in dimethyl maleate revealed by addition of thiols
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Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) have become important techniques in many research areas. One major limitation is the relatively low sensitivity of these methods, which recently has been addressed by hyperpolarization. However, once hyperpolarization is imparted on a molecule, the magnetization typically decays within relatively short times. Singlet states are well isolated from the environment, such that they acquire long lifetimes. We describe herein a model reaction for read-out of a hyperpolarized long-lived state in dimethyl maleate using thiol conjugate addition. This type of reaction could lend itself to monitoring oxidative stress or hypoxia by sensitive detection of thiols. Similar reactions could be used in biosensors or assays that exploit molecular switching. Singlet lifetimes of about 4.7 min for 1H spins in [D4]MeOH are seen in this system. Hyperpolarized singlet states are well isolated from the environment, such that they acquire long lifetimes. Here, we used the thiol conjugate addition to unveil the hyperpolarized long-lived singlet state in deuterated dimethyl maleate (see picture). Singlet lifetimes of 4.7 min for 1H spins in [D4]MeOH are seen in this system.
- Zhang, Yuning,Soon, Pei Che,Jerschow, Alexej,Canary, James W.
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- Bichromophoric Compounds. Photophysics and Photochemistry of (1-Naphthyl)alkyl Esters of Fumaric, Maleic, and Oxalic Acids
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Fumarate, maleate, and oxalate groups quench the excited singlet state of naphthalene.When the naphthalene chromophore is combined in the same molecule with one of these quenching groups, its fluorescence quantum yield is reduced to about 1percent of that of the corresponding (1-naphthyl)alkyl acetate as a result of efficient electron transfer to the diester.No exciplex emission is observed from the bichromophoric compounds.Although the rate of quenching is only weakly dependent on the number of atoms linking the two groups, ground-state charge-transfer interactions between the two groups were observed only in the di-1-naphthyl esters and were absent when the groups were separated by longer chains. (1-Naphthyl)alkyl fumarates and maleates undergo photochemical cis-trans isomerization with quantum yields on the order of 0.04.This photoisomerization was shown to proceed via the electron-transfer pathway and not by direct triplet energy transfer from the naphthalene chromophore to the unsaturated diester.The 1-naphthylmethyl esters yield 1-naphthaldehyde with quantum yields of 0.001.Free-radical chain addition to the fumarate double bond occurs on prolonged irradiation in solvents containing abstractable H, particularly in the presence of acetophenone or radical sources such as tert-butyl hydroperoxide.Even in thoroughly degassed benzene oligomerization of the fumarate group leads to partial loss of the double bond at long irradiation times.
- Holden, David A.,Gray, J. Bradley,McEwan, Ian
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- Cu(OAc)2-2,4-lutidine-ZnCl2 as an effective catalyst of functionalization of isobutylene oligomers and 1,2-polybutadiene with methyl diazoacetate
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The possibility of [1+2]-cycloaddition of methoxycarbonylcarbene generated by catalytic decomposition of methyl diazoacetate in the presence of the Cu(OAc)2-2,4-lutidine-ZnCl2 system to the carbon-carbon double bound in isobutylene o
- Gareev,Yangirov,Volodina,Sultanova,Biglova,Dokichev
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- o-Fluoranil: Stereochemistry and mechanism of its Diels-Alder reactions
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(Chemical Equation Presented) In the absence of significant steric effects, Diels-Alder reactions of the title quinone generally take place with preservation of configuration, and are therefore probably concerted. However, hybrid density functional calcul
- Lemal, David M.,Sang, Dayong,Ramanathan, Sudharsanam
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- Limits in Proton Nuclear Singlet-State Lifetimes Measured with para-Hydrogen-Induced Polarization
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The synthesis of a hyperpolarized molecule was developed, where the polarization and the singlet state were preserved over two controlled chemical steps. Nuclear singlet-state lifetimes close to 6 min for protons are reported in dimethyl fumarate. Owing to the high symmetry (AA′X3X3′ and A2 systems), the singlet-state readout requires either a chemical desymmetrization or a long and repeated spin lock. Using DFT calculations and relaxation models, we further determine nuclear spin singlet lifetime limiting factors, which include the intramolecular dipolar coupling mechanism (proton–proton and proton–deuterium), the chemical shift anisotropy mechanism (symmetric and antisymmetric), and the intermolecular dipolar coupling mechanism (to oxygen and deuterium). If the limit of paramagnetic relaxation caused by residual oxygen could be lifted, the intramolecular dipolar coupling to deuterium would become the limiting relaxation mechanism and proton lifetimes upwards of 26 min could become available in the molecules considered here (dimethyl maleate and dimethyl fumarate).
- Zhang, Yuning,Duan, Xueyou,Soon, Pei Che,Canary, James W.,Jerschow, Alexej,Sychrovsky, Vladimír
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- Method for preparing diacid diester compound under catalysis of deep eutectic solvent
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The invention belongs to the technical field of organic synthesis, and discloses a method for preparing a diacid diester compound through catalysis of a deep eutectic solvent, wherein the deep eutectic solvent takes ammonium salt and ferric salt as hydrogen acceptors, takes p-toluenesulfonic acid as a hydrogen donor, takes diacid or anhydride of the diacid and an alcohol compound as raw materials, and adopts a one-pot method to prepare the diacid diester compound; and under the catalysis of the deep eutectic solvent, the esterification reaction is performed to generate the diester product. The selected deep eutectic solvent has characteristics of environmental protection, easy preparation, cheap components and easy recovery; the preparation method has characteristics of simple operation, simple separation, no water-carrying agent, repeated use of the deep eutectic solvent, and high diester yield.
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Paragraph 0055-0058
(2021/05/19)
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- Self-Assembled Open Porous Nanoparticle Superstructures
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Imparting porosity to inorganic nanoparticle assemblies to build up self-assembled open porous nanoparticle superstructures represents one of the most challenging issues and will reshape the property and application scope of traditional inorganic nanoparticle solids. Herein, we discovered how to engineer open pores into diverse ordered nanoparticle superstructures via their inclusion-induced assembly within 1D nanotubes, akin to the molecular host-guest complexation. The open porous structure of self-assembled composites is generated from nonclose-packing of nanoparticles in 1D confined space. Tuning the size ratios of the tube-to-nanoparticle enables the structural modulation of these porous nanoparticle superstructures, with symmetries such as C1, zigzag, C2, C4, and C5. Moreover, when the internal surface of the nanotubes is blocked by molecular additives, the nanoparticles would switch their assembly pathway and self-assemble on the external surface of the nanotubes without the formation of porous nanoparticle assemblies. We also show that the open porous nanoparticle superstructures can be ideal candidate for catalysis with accelerated reaction rates.
- Liu, Rongjuan,Wei, Jingjing,Wei, Yanze,Yang, Zhijie,Zhang, Fenghua
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supporting information
(2021/08/20)
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- Chemical Reaction Monitoring using Zero-Field Nuclear Magnetic Resonance Enables Study of Heterogeneous Samples in Metal Containers
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We demonstrate that heterogeneous/biphasic chemical reactions can be monitored with high spectroscopic resolution using zero-field nuclear magnetic resonance spectroscopy. This is possible because magnetic susceptibility broadening is negligible at ultralow magnetic fields. We show the two-step hydrogenation of dimethyl acetylenedicarboxylate with para-enriched hydrogen gas in conventional glass NMR tubes, as well as in a titanium tube. The low frequency zero-field NMR signals ensure that there is no significant signal attenuation arising from shielding by the electrically conductive sample container. This method paves the way for in situ monitoring of reactions in complex heterogeneous multiphase systems and in reactors made of conductive materials while maintaining resolution and chemical specificity.
- Blanchard, John W.,Budker, Dmitry,Burueva, Dudari B.,Eills, James,Garcon, Antoine,Koptyug, Igor V.,Kovtunov, Kirill V.,Picazo-Frutos, Román
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p. 17026 - 17032
(2020/07/30)
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- A Br?nsted acidic, ionic liquid containing, heteropolyacid functionalized polysiloxane network as a highly selective catalyst for the esterification of dicarboxylic acids
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A Br?nsted acidic, ionic liquid containing, heteropolyanion functionalized polysiloxane network was formed by self-condensation of dodecatungstophosphoric acid and a zwitterionic organosilane precursor containing both imidazolinium and sulfonate groups. The resulting hybrid material POS-HPA-IL was investigated as a catalyst for the selective esterification of dicarboxylic acids.
- Rajabi, Fatemeh,Wilhelm, Christian,Thiel, Werner R.
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supporting information
p. 4438 - 4444
(2020/08/10)
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- Method for preparing maleate by catalyzing maleic anhydride with ionic liquid
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The invention discloses a method for preparing maleate by catalyzing maleic anhydride with ionic liquid. The preparation method is characterized by comprising the following steps: mixing ionic liquidwith maleic anhydride and fatty alcohol, carrying out heating to 80-140 DEG C, and performing a reaction for 0.5-4 h to obtain maleate, wherein the usage amount of the ionic liquid accounts for 0.1-10% by mol of the maleic anhydride, and a molar ratio of fatty alcohol to maleic anhydride is 2-12. A high-added-value chemical with the completely-esterified maleate as a main product is prepared in the invention. The method is simple in process, mild in conditions, friendly to environment and high in double esterification degree; and the ionic liquid is high in activity, not prone to inactivationand capable of being cyclically used.
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Paragraph 0025; 0030; 0031; 0036
(2020/02/29)
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- Study of the Oxidative Cleavage Proposed in the Biogenesis of Transtaganolides/Basiliolides: Pyran-2-one Aromaticity-Mediated Regioselective Control and Biogenetic Implications
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The synthetic feasibility of the oxidative cleavage: epoxidation of 7-O-geranylscopoletin followed by electrocyclic ring-opening, proposed in the biogenesis of transtaganolides/basiliolides is studied. Unlike the proposed pericyclic reactions, this pathway has not yet been addressed. Three synthetic strategies have been tested consisting of: i) Baeyer–Villiger oxidation of p-quinoids, ii) hydrolysis of quinone monoketals, or iii) direct fragmentation by using oxygen donors. Oxidation of the benzene ring of hydroxylated coumarins has been achieved using peroxyacids, but cleavage took place between undesired positions. The aromaticity conservation of the pyran-2-one cycle during oxidation is the controlling factor of these observed regioselectivities. The use of a 4,5-dihydroxy-2-methoxycinnamate model, in which the pyran-2-one ring does not exert influence on oxidation, has allowed the design of a synthetic sequence toward an analogue of the natural pyran-2-one isolated from Thapsia transtagana, key in the biogenesis. Mechanistic proposals for the obtained results as well as their biogenetic implications are raised.
- álvarez, José María,Jorge, Zacarías D.,Massanet, Guillermo M.
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- Substituent Effects on Reactions of [RhCl(COD)]2 with Diazoalkanes
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The reactions of [RhCl(COD)]2 with a series of diazoalkanes with different substitutents were investigated. The outcomes of the reactions were found to be substituent-dependent via four different pathways. (1) The reactions with diazoindenes produced ??5-cyclopentadienyl complexes. (2) The reaction with diazofluorene produced a mixture of olefin and azine compounds. (3) The reactions with monosubstituted diazoalkanes RCHN2 (R = Ph, MeO2C) produced olefins RCHa?CHR. (4) The reaction with the disubstituted diazoalkane Ph2CN2 produced the azine Ph2Ca?N-Na?CPh2 only. Computational studies have been carried out to understand the interesting substituent effect by comparing the kinetics and thermodynamics of the reaction pathways. It was found that the reactions with diazocyclopentadiene, diazoindene, and Ph2CN2 are kinetically controlled, while the reactions with RCHN2 and diazofluorene are both thermodynamically and kinetically controlled.
- Cui, Mingxu,Lin, Shujuan,Sung, Herman H. Y.,Williams, Ian D.,Lin, Zhenyang,Jia, Guochen
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p. 905 - 915
(2019/03/04)
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- Palladium nanodendrites uniformly deposited on the surface of polymers as an efficient and recyclable catalyst for direct drug modification via Z-selective semihydrogenation of alkynes
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The preparation of new monodisperse polycrystalline palladium nanoparticles uniformly distributed on the surface of polymers, by simply adding a palladium(ii) solution in water to the polymers, is described. The polymer supported palladium nanoparticles material was used as an efficient portable and reusable catalyst for the stereoselective semihydrogenation reaction of internal alkynes to (Z)-alkenes in green solvents.
- García-Calvo, José,Calvo-Gredilla, Patricia,Vallejos, Saúl,García, José Miguel,Cuevas-Vicario, José Vicente,García-Herbosa, Gabriel,Avella, Manuel,Torroba, Tomás
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supporting information
p. 3875 - 3883
(2018/08/21)
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- Cuboidal Mo3S4 Clusters as a Platform for Exploring Catalysis: A Three-Center Sulfur Mechanism for Alkyne Semihydrogenation
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We report a trinuclear Mo3S4 diamino cluster that promotes the semihydrogenation of alkynes. Based on experimental and computational results, we propose an unprecedented mechanism in which only the three bridging sulfurs of the cluster act as the active site for this transformation. In the first step, two of these μ-S ligands react with the alkyne to form a dithiolene adduct; this process is formally analogous to the olefin adsorption on MoS2 surfaces. Then, H2 activation occurs in an unprecedented way that involves the third μ-S center, in cooperation with one of the dithiolene carbon atoms. Notably, this step does not imply any direct interaction between H2 and the metal centers, and directly results in the formation of an intermediate featuring one (μ-S)-H and one C-H bond. Finally, such half-hydrogenated intermediate can either undergo a reductive elimination step that results in the Z-alkene product, or evolve into an isomerized analogue whose subsequent reductive elimination generates the E-alkene product. Interestingly, the substituents on the alkynes have a major impact on the relative barriers of these two processes, with the semihydrogenation of dimethyl acetylenedicarboxylate (dmad) resulting in the stereoselective formation of dimethyl maleate, whereas that of diphenylacetylene (dpa) leads to mixtures of Z- and E-stilbene. The results herein could have significant implications on the understanding of the catalytic properties of MoS2-based materials.
- Algarra, Andrés G.,Guillamón, Eva,Andrés, Juan,Fernández-Trujillo, M. Jesús,Pedrajas, Elena,Pino-Chamorro, Jose ángel,Llusar, Rosa,Basallote, Manuel G.
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p. 7346 - 7350
(2018/07/21)
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- Photoorganocatalytic synthesis of lactones: Via a selective C-H activation-alkylation of alcohols
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Selective C-H activation is an area of growing importance in modern organic chemistry. Herein, we report our efforts in combining organocatalysis and photocatalysis for the development of a highly efficient and selective visible-light mediated protocol for the C-H activation and addition of various alcohols to a plethora of Michael acceptors, followed by a cyclization reaction leading to lactones, a repeatedly occurring motif in nature. Utilizing phenylglyoxylic acid as the photocatalyst and common household bulbs as the light source, we describe a versatile α-alkylation/lactonization of alcohols with α,β-unsaturated esters leading to products in excellent yields. The reaction mechanism was extensively studied.
- Kaplaneris, Nikolaos,Bisticha, Aikaterini,Papadopoulos, Giorgos N.,Limnios, Dimitris,Kokotos, Christoforos G.
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supporting information
p. 4451 - 4456
(2017/09/29)
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- A new synthon for the synthesis of aminoinositol derivatives
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The regio- and stereoselective synthesis of a new synthon, trans-3,8-dioxatricyclo[3.2.1.02,4]octane-6,7-diamine, from 7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate is reported. Transformation of the acid functionalities to acyl azides followed by Curtius rearrangement gave the corresponding trans-diisocyanate, which was reacted with HCl to produce a trans-diamino compound that is a potentially important synthon for the versatile synthesis of aminocyclitols.
- Cokol, Nalan Korkmaz,Kaya, Serdal,Balci, Metin
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p. 2732 - 2735
(2017/06/23)
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- The MOF-driven synthesis of supported palladium clusters with catalytic activity for carbene-mediated chemistry
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The development of catalysts able to assist industrially important chemical processes is a topic of high importance. In view of the catalytic capabilities of small metal clusters, research efforts are being focused on the synthesis of novel catalysts bearing such active sites. Here we report a heterogeneous catalyst consisting of Pd4 clusters with mixed-valence 0/+1 oxidation states, stabilized and homogeneously organized within the walls of a metal-organic framework (MOF). The resulting solid catalyst outperforms state-of-the-art metal catalysts in carbene-mediated reactions of diazoacetates, with high yields (>90%) and turnover numbers (up to 100,000). In addition, the MOF-supported Pd4 clusters retain their catalytic activity in repeated batch and flow reactions (>20 cycles). Our findings demonstrate how this synthetic approach may now instruct the future design of heterogeneous catalysts with advantageous reaction capabilities for other important processes.
- Fortea-Pérez, Francisco R.,Mon, Marta,Ferrando-Soria, Jesús,Boronat, Mercedes,Leyva-Pérez, Antonio,Corma, Avelino,Herrera, Juan Manuel,Osadchii, Dmitrii,Gascon, Jorge,Armentano, Donatella,Pardo, Emilio
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p. 760 - 766
(2017/07/04)
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- Method for synthesizing carboxylic methyl ether by reaction between acid anhydrides and dimethyl carbonate
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The invention discloses a method for synthesizing carboxylic methyl ether by a reaction between acid anhydrides and dimethyl carbonate. The method is characterized by comprising the following steps: taking raw materials acid anhydride, dimethyl carbonate and a catalyst, wherein molar ratio of acid anhydride to dimethyl carbonate is 1:1-1:100, the catalyst accounts for 1-20 wt% of mass of acid anhydride, acid anhydride is aliphatic acid anhydride or aromatic acid anhydride, and the catalyst is Lewis acid or protonic acid; adding acid anhydride, dimethyl carbonate and the catalyst into a high-pressure reaction vessel, reacting at 80-350 DEG C for 1-8h, cooling to room temperature, discharging gas, and fetching a material obtained after the reaction; pouring the material into a saturated sodium bicarbonate aqueous solution, extracting with ethyl acetate or dichloromethane, merging extract liquor, drying, filtering, and distilling a filtrate to remove a solvent. The remaining product is prepared carboxylic methyl ether. By the method, no additional organic solvent is required. The method is green and environment-friendly, is simple to operate, has short reaction time, has high acid anhydride conversion rate, and has a good application prospect.
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Paragraph 0016
(2017/08/28)
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- Method of selectively catalytically oxidizing biomass-based furan compound
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The invention discloses a method of selectively catalytically oxidizing a biomass-based furan compound. The method comprises the following step of: by taking a heteropolyacid functional ionic liquid as a catalyst and an alcohol solution as a reaction medium, obtaining dicarboxylic acid or dicarboxylate in the conditions that the reaction temperature is 100-150 DEG C, the reaction time is 1-3h and the oxygen pressure is 0.5-1.0MPa, wherein over 62.35% of difumarate selectivity is obtained. The single chemical yield and selectivity for oxidizing preparation of a biomass-based furan derivative are far higher than those of the prior art. The method has the remarkable advantage that an ionic liquid catalyst can be recovered and recycled by simply adjusting the temperature. The method disclosed by the invention is mild in reaction condition, green and safe in process and simple to operate, and can realize intermittent and continuous production.
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Paragraph 0110-0113
(2017/07/19)
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- Synthesis process of dimethyl maleate
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The invention discloses a synthesis process of dimethyl maleate. The synthesis process comprises steps as follows: maleic anhydride and methanol are subjected to a reaction in a mono-esterification reaction kettle at the temperature of 70-100 DEG C, and monomethyl maleate is generated; monomethyl maleate enters a catalytic esterification tower from a tower, methanol steam enters the catalytic esterification tower from the position below upper liquid level of each layer of tower plate and is contacted with monomethyl maleate and a solid catalyst on the tower plate, and dimethyl maleate is generated. With the adoption of continuous production, energy utilization rate is increased by full use of waste heat of the esterification reaction; with the adoption of multiple methanol steam inputs, methanol steam is distributed on each tower plate, each tower plate forms one small reactor in a boiling state, the contact area of monomethyl maleate and methyl alcohol is increased, the contact time of monomethyl maleate and methyl alcohol is prolonged, the problem of uneven distribution of methanol in the tower due to liquefied reflow of the methyl alcohol steam in a rising process is solved, the reaction efficiency and the esterification rate are increased, the methanol utilization rate is increased, the production cost is reduced while the yield is increased, and the synthesis process is suitable for industrial application.
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Paragraph 0010
(2017/07/01)
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- Selective partial hydrogenation of alkynes to (Z)-alkenes with ionic liquid-doped nickel nanocatalysts at near ambient conditions
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A selective hydrogenation method for forming (Z)-alkenes from alkynes has been developed using a catalyst system of cheap Ni-NPs in a nitrile functionalised imidazolium based ionic liquid (IL) operating under very mild reaction conditions of 30-50 °C and 1-4 bar H2 pressure.
- Konnerth, Hannelore,Prechtl, Martin H. G.
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supporting information
p. 9129 - 9132
(2016/07/22)
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- Template-free sol–gel synthesis of high surface area mesoporous silica based catalysts for esterification of di-carboxylic acids
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High surface area mesoporous silica based catalysts have been prepared by a simple hydrolysis/sol–gel process without using any organic template and hydrothermal treatment. A controlled hydrolysis of ethyl silicate-40, an industrial bulk chemical, as a silica precursor, resulted in the formation of very high surface area (719?m2/g) mesoporous (pore size 67?? and pore volume 1.19?cc/g) silica. The formation of mesoporous silica has been correlated with the polymeric nature of the ethyl silicate-40 silica precursor which on hydrolysis and further condensation forms long chain silica species which hinders the formation of a close condensed structure thus creating larger pores resulting in the formation of high surface mesoporous silica. Ethyl silicate-40 was used further for preparing a solid acid catalyst by supporting molybdenum oxide nanoparticles on mesoporous silica by a simple hydrolysis sol–gel synthesis procedure. The catalysts showed very high acidity as determined by NH3-TPD with the presence of Lewis as well as Br?nsted acidity. These catalysts showed very high catalytic activity for esterification; a typical acid catalyzed organic transformation of various mono- and di-carboxylic acids with a range of alcohols. The in situ formed silicomolybdic acid heteropoly-anion species during the catalytic reactions were found to be catalytically active species for these reactions. Ethyl silicate-40, an industrial bulk silica precursor, has shown a good potential for its use as a silica precursor for the preparation of mesoporous silica based heterogeneous catalysts on a larger scale at a lower cost.
- More, Pavan M.,Umbarkar, Shubhangi B.,Dongare, Mohan K.
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p. 1247 - 1253
(2016/10/13)
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- Catalytic oxidative C-C bond cleavage route of levulinic acid and methyl levulinate
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Recently, obtaining value-added chemicals from biomass resources has attracted considerable attention. Levulinic acid is one of the most important biomass platform compounds, which could be obtained from carbohydrate biomass. In this work, levulinic acid was selectively converted into C4 product, including succinic anhydride, via catalytic oxidation with a manganese catalyst in acetic anhydride. Moreover, an unexpected product of maleic anhydride was obtained, which greatly differs from that of levulinate ester. The pathway for formation of maleic anhydride was studied by monitoring and confirming intermediates α-angelica lactone and its derivative 2-methyl-5-oxotetrahydro-2-furanyl acetate. Based on the obtained mechanistic information, the different behaviour between the oxidative cleavage of levulinic acid and levulinate ester was further discussed.
- Xia, Fei,Du, Zhongtian,Liu, Junxia,Ma, Yangyang,Xu, Jie
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p. 72744 - 72749
(2016/08/09)
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- Versatile PdTe/C catalyst for liquid-phase oxidations of 1,3-butadiene
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A commercial Pd catalyst based on Sibunit carbon support was treated with H6TeO6 in a reducing media to obtain a Te coating on the surface of Pd particles. The PdTe/C catalyst prepared in this way showed the ability to control the radical chain oxidation of 1,3-butadiene by promoting the selective formation of 2-butene-1,4-diol, 4-hydroxybut-2-enal and furan in DMA (total selectivity of 61% and yield of 7%). At the same time, the catalyst induced oxidation of 1,3-butadiene by a non-radical heterolytic mechanism involving the formation of two groups of primary products: (1) crotonaldehyde and methyl vinyl ketone and (2) the products of oxygenation at the 1,4-positions. The compounds of the second group including 1,4-dimethoxy-2-butene and maleic acid dimethyl ester were formed on PdTe centers in MeOH. Increasing the Te concentration in the PdTe/C catalyst forced the conversion of 1,3-butadiene toward 1,4-oxygenation and simultaneously decreased the intensity of secondary oxidation, resulting in the selective formation of derivatives of the 1,4-oxygenation - 1,4-dimethoxy-2-butene and allenic alcohol methyl ether (total selectivity of 84% and yield of 48%).
- Kuznetsova,Zudin,Kuznetsova,Zaikovskii,Kajitani,Utsunomiya,Takahashi
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- PROCESS FOR CARRYING OUT A REACTION IN A REACTION COLUMN
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A process for carrying out a reaction in a reaction column, said process comprising: providing a first reactant to the reaction column in the liquid phase; contacting said first reactant with an excess of a second reactant such that reaction takes place within the reaction column to form a low boiling product and a high boiling product, at least a portion of said second reactant being provided to the reaction column in the vapour phase; recovering an overhead stream from at, or near, the top of the reaction column, said overhead stream comprising unreacted second reactant and the low boiling product; and recovering a bottoms stream from at, or near, the bottom of the reaction column comprising the high boiling product; wherein at least a portion of the heat required to vaporise the second reactant provided to the reaction column in the vapour phase is provided by heat exchange in a heat exchanger with a hot stream generated within the process other than a hot stream generated within the reaction column.
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Page/Page column 14-15
(2016/10/11)
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- POLYGLYOXYLATES, MANUFACTURE AND USE THEREOF
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Self-immolative polymers degrade by an end-to-end depolymerisation mechanism in response to the cleavage of a stabilizing end-cap from the polymer terminus. Examples include homopolymers, mixed polymers including block copolymers, suitable for a variety of applications. A polyglyoxylate can be end-capped or capped with a linker as in a block copolymer.
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Page/Page column 23
(2015/11/27)
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- New reactions of terminal hydrides on a diiron dithiolate
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Mechanisms for biological and bioinspired dihydrogen activation and production often invoke the intermediacy of diiron dithiolato dihydrides. The first example of such a Fe2(SR)2H2 species is provided by the complex [(term-H)(μ-H)Fe2(pdt)(CO)(dppv) 2] ([H1H]0). Spectroscopic and computational studies indicate that [H1H]0 contains both a bridging hydride and a terminal hydride, which, notably, occupies a basal site. The synthesis begins with [(μ-H)Fe2(pdt)(CO)2(dppv)2]+ ([H1(CO)]+), which undergoes substitution to afford [(μ-H)Fe 2(pdt)(CO)(NCMe)(dppv)2]+ ([H1(NCMe)] +). Upon treatment of [H1(NCMe)]+ with borohydride salts, the MeCN ligand is displaced to afford [H1H]0. DNMR (EXSY, SST) experiments on this complex show that the terminal and bridging hydride ligands interchange intramolecularly at a rate of 1 s-1 at -40 °C. The compound reacts with D2 to afford [D1D]0, but not mixed isotopomers such as [H1D]0. The dihydride undergoes oxidation with Fc+ under CO to give [1(CO)]+ and H2. Protonation in MeCN solution gives [H1(NCMe)]+ and H2. Carbonylation converts [H1H]0 into [1(CO)]0.
- Wang, Wenguang,Rauchfuss, Thomas B.,Zhu, Lingyang,Zampella, Giuseppe
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p. 5773 - 5782
(2014/05/06)
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- Polyglyoxylates: A versatile class of triggerable self-immolative polymers from readily accessible monomers
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Self-immolative polymers, which degrade by an end-to-end depolymerization mechanism in response to the cleavage of a stabilizing end-cap from the polymer terminus, are of increasing interest for a wide variety of applications ranging from sensors to controlled release. However, the preparation of these materials often requires expensive, multistep monomer syntheses, and the degradation products such as quinone methides or phthalaldehydes are potentially toxic to humans and the environment. We demonstrate here that polyglyxoylates can serve as a new and versatile class of self-immolative polymers. Polymerization of the commercially available monomer ethyl glyoxylate, followed by end-capping with a 6-nitroveratryl carbonate, provides a poly(ethyl glyoxylate) that depolymerizes selectively upon irradiation with UV light, ultimately generating ethanol and the metabolic intermediate glyoxylic acid hydrate. To access polyglyoxylates with different properties, the polymerization and end-capping approach can also be extended to other glyoxylate monomers including methyl glyoxylate, n-butyl glyoxylate, and benzyl glyoxylate, which can be easily prepared from their corresponding fumaric or maleic acid derivatives. Random copolymers of these monomers with ethyl glyoxylate can also be prepared. Furthermore, using a multifunctional end-cap that is UV-responsive and also enables the conjugation of another polymer block via an azide-alkyne "click" cycloaddition, amphiphilic self-immolative block copolymers are also prepared. These block copolymers self-assemble into micelles in aqueous solution, and their poly(ethyl glyoxylate) blocks rapidly depolymerize upon UV irradiation. Overall, these strategies are expected to greatly expand the utility of self-immolative polymers by providing access for the first time to self-immolative polymers with tunable properties that can be readily obtained from simple monomers and can be designed to depolymerize into nontoxic products.
- Fan, Bo,Trant, John F.,Wong, Andrew D.,Gillies, Elizabeth R.
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supporting information
p. 10116 - 10123
(2014/08/05)
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- Cross-metathesis of methyl 10-undecenoate with dimethyl maleate: An efficient protocol with nearly quantitative yields
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In this cross metathesis of the renewable raw material methyl 10-undecenoate with dimethyl maleate, an α,ω-difunctional product was produced. Detailed optimizations led to nearly quantitative yields of the desired product. The cross metathesis of methyl 10-undecenoate with methyl acrylate yielded high conversions of the substrate. The product was accessed under mild reaction conditions with the use of a small amount of a commercially available homogeneous ruthenium catalyst. The in situ synthesis of dimethyl maleate from maleic anhydride was also possible in this reaction system. This journal is the Partner Organisations 2014.
- Behr,Toepell,Harmuth
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p. 16320 - 16326
(2014/05/06)
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- Promoted role of Cu(NO3)2 on aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran over VOSO4
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The promoted effect of Cu(NO3)2 on aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) catalyzed by VOSO4 in acetonitrile was intensively investigated. It was revealed that Cu(NO3)2 facilitated the activation of VOSO 4 to generate active V5+ species via the generation of NOx gas. The high DFF selectivity is ascribed to Cu2+ cation which can effectively prohibit oxidative CC bond cleavage reaction of HMF and prevent radical reaction of DFF to humins. In addition, the polarity of solvent plays a great role on high selectivity of DFF.
- Jia, Xiuquan,Ma, Jiping,Wang, Min,Du, Zhongtian,Lu, Fang,Wang, Feng,Xu, Jie
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p. 231 - 236
(2014/07/08)
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- METHOD FOR CONTINUOUSLY PREPARING CARBOXYLIC ACID ESTER
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A method for continuously preparing a carboxylic acid ester is disclosed. In the method of the present invention, a vertical reactor is filled with a solid catalyst, a carboxylic acid and an alcohol are introduced into a lower part of the vertical reactor, esterification is performed to form an esterized mixture, the esterized mixture is output from an upper part of the vertical reactor, and distillation is performed to isolate the carboxylic acid ester. The method of the present invention is simple, easily controlled and environmental friendly, and has significantly high conversion rate and selectivity.
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Paragraph 0032; 0034
(2013/11/19)
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- Palladium phthalocyaninesulfonate functionalized mesoporous polymer: A highly efficient photocatalyst for degradation of 4-chlorophenol under visible light irradiation
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A novel sulfonated palladium phthalocyanine (PdPcS) modified FDU-15 mesoporous polymer (FDU-PdPcS) has been prepared by rationally chemical modification process. The PdPcS molecules were highly dispersed inside the confined mesopores, and were further stabilized through a π-π interaction with mesopolymer, which may prevent the PdPcS molecules from agglomerating and deactivating in photodegradation reactions. The physicochemical properties of thus prepared FDU-PdPcS material were characterized by XRD, N2 adsorption-desorption, UV-vis and inductively coupled plasma techniques. FDU-PdPcS proved to be highly efficient heterogeneous photocatalyst for the degradation of 4-chlorophenol (4-CP) in the presence of H2O 2 under visible light irradiation. The photodegradation of 4-CP with an initial concentration 0.6 mM was completed within 5 h at pH 11 using a dose of 0.2 g/L of the 0.12 wt% FDU-PdPcS photocatalyst. The photodegradation intermediates were identified by GC-MS. A possible mechanism involved in the photodegradation of 4-CP has also been discussed.
- Xing, Rong,Wu, Lin,Fei, Zhenghao,Wu, Peng
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- Gold-catalyzed dehydrogenative cycloaddition of tethered 1,n-dihydrodisilanes to alkynes
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Gold nanoparticles supported on TiO2 (0.1-2% mol) catalyze at mild conditions the dehydrogenative addition of tethered 1,n-dihydrodisilanes, such as 1,1,3,3-tetramethyldisiloxane (1), 1,1,3,3-tetraphenyldisiloxane (2), 1,1,1,3,5,7,7,7-octamethyltetrasiloxane (3), 1,1,3,3,5,5-hexamethyltrisiloxane (4), and 1,2-bis(dimethylsilyl)benzene (5), to alkynes, forming cycloadducts and releasing H2. Under the same conditions, polymeric methylhydrosiloxane is completely unreactive. For the majority of terminal alkynes and 1,n-dihydrodisilanes the yields are excellent (up to 99%). In general, terminal alkynes are more reactive as compared to internal. The reaction tolerates several functional groups and can be performed in a variety of solvents. In the case of 1,1,3,3-tetramethyldisiloxane, it is proposed that gold nanoparticles form intermediate cyclo-gold-tetramethyldisiloxane via a dehydrogenative pathway, which undergoes a formal [3+2] cycloaddition to alkynes.
- Kotzabasaki, Vasiliki,Lykakis, Ioannis N.,Gryparis, Charis,Psyllaki, Androniki,Vasilikogiannaki, Eleni,Stratakis, Manolis
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p. 665 - 672
(2013/03/14)
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- Mechanisms by which alkynes react with CpCr(CO)3H. Application to radical cyclization
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The reaction of CpCr(CO)3H with activated alkynes in benzene has been examined. The kinetics of these reactions have been studied with various alkynes, along with the stereochemistry with which the alkynes are hydrogenated. The hydrogenation of phenyl acetylene and diphenyl acetylene with CpCr(CO) 3H has been shown to occur by a hydrogen atom transfer (HAT) mechanism. The reaction of CpCr(CO)3H with dimethyl acetylenedicarboxylate (DMAD) produced hydrogenated products as well as phenyl substitution from reaction with solvent. On the basis of kinetic data, it is thought that the reaction of DMAD may proceed via a single electron transfer (SET) as the rate-determining step. The radical anion of dimethylfumarate was observed by EPR spectroscopy during the course of the reaction, supporting this claim. The aromatic 1,6 eneyne (8) gave cyclized products in 78% yield under catalytic conditions (35 psi H2), presumably by the 5-exo-trig cyclization of the vinyl radical arising from H? transfer. Using a cobaloxime catalyst (12) hydrogenation was completely eliminated to yield 100% cyclized products.
- Estes, Deven P.,Norton, Jack R.,Jockusch, Steffen,Sattler, Wesley
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p. 15512 - 15518
(2012/11/13)
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- A convenient procedure for bis-esterification of cyclic anhydrides
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Aromatic and aliphatic cyclic anhydrides are chemoselectively and conveniently transformed to the corresponding diesters by the use of DBU and appropriate alkyl/allyl halides. This bis-esterification reaction has been exemplified mostly with dimethyl esters. But in some cases, mixed dialkyl esters are also prepared.
- Jana, Amit Kumar,Karmakar, Raju,Dinda, Bidyut Kumar,Mitra, Prithiba,Ghosh, Ketaki,Karmakar, Rajdip,Mal, Dipakranjan
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p. 975 - 979
(2012/10/29)
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- Highly selective iron-catalyzed synthesis of alkenes by the reduction of alkynes
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Herein, the iron-catalyzed reduction of a variety of alkynes with silanes as a reductant has been examined. With a straightforward catalyst system composed of diiron nonacarbonyl and tributyl phosphane, excellent yields and chemoselectivities (>99 %) were obtained for the formation of the corresponding alkenes. After studying the reaction conditions, and the scope and limitations of the reaction, several attempts were undertaken to shed light on the reaction mechanism. Im Rahmen dieser Arbeit wird die Eisen-katalysierte Reduktion von Alkinen zu den entsprechenden Alkenen mit Hilfe von Silanen vorgestellt. Hierbei konnten exzellente Ausbeuten und Selektivitaeten (>99 %) durch die Modifikation des eingesetzten Eisenkatalysators mit Phosphanen beobachtet werden. Nach genauer Untersuchung verschiedenster Reaktionsparameter wurden die hervorragenden Eigenschaften des Katalysatorsystems in der Reduktion zahlreicher Alkine gezeigt. Zum besseren Verstaendnis der Reaktion wurden verschiedene mechanistische Experimente durchgefuehrt. Iron Made′m: In situ generated iron complexes catalyze the reduction of alkynes with silanes as a hydride source with excellent selectivity (>99 %). Copyright
- Enthaler, Stephan,Haberberger, Michael,Irran, Elisabeth
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experimental part
p. 1613 - 1623
(2012/06/04)
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- Polymer-mounted N3=P(MeNCH2CH2) 3N: A green, efficient and recyclable catalyst for room-temperature transesterifications and amidations of unactivated esters
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Merrifield resin-supported N3P(MeNCH2CH 2)3N shows excellent activity in the transesterification of higher esters such as glyceryl tribenzoate to methyl esters. The catalyst was successfully cycled 20 times (albeit with an increase in reaction time) without compromising yield up to the 20th cycle. The catalyst also showed good performance in amidation reactions of unactivated esters with amino alcohols.
- Chintareddy, Venkat Reddy,Ho, Hung-An,Sadow, Aaron D.,Verkade, John G.
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experimental part
p. 6523 - 6529
(2011/12/21)
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- One-pot esterification and Ritter reaction: Chemo- and regioselectivity from tert-butyl methyl ether
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tert-Butyl methyl ether (TBME) has been effectively used as a reagent for esterification of carboxylic acids. By varying amounts of sulfuric acid, a remarkable regioselectivity in esterification has been demonstrated. Additionally, under the present reaction conditions, one-pot esterification and Ritter reaction are achieved in almost quantitative yield.
- Dawar, Pankaj,Bhagavan Raju,Ramakrishna, Ramesha A.
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supporting information; experimental part
p. 4262 - 4265
(2011/08/21)
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- Oxidative cycloaddition of 1,1,3,3-Tetramethyldisiloxane to alkynes catalyzed by supported gold nanoparticles
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Gold nanoparticles supported on TiO2 (0.1-1% mol) catalyze at room temperature and at extremely mild conditions the unprecedented oxidative cycloaddition of 1,1,3,3-tetramethyldisiloxane to alkynes, forming substituted 2,5-dihydro-1,2,5-oxadisiloles, with concomitant evolution of hydrogen gas. For the majority of the substrates, the yields are exceptional (up to 99%). The reaction proceeds at room temperature, tolerates a variety of functional groups, and can be performed in several solvents.
- Lykakis, Ioannis N.,Psyllaki, Androniki,Stratakis, Manolis
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experimental part
p. 10426 - 10429
(2011/08/05)
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- Effect of imidazolium salts on the catalytic reaction of 1,3-dioxolanes with methyl diazoacetate
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Effect of imidazolium salts, [bmim]+Cl-, [bmim] +BF4 -, and [bmim]+PF6 -, on the reaction of 1,3-dioxolanes with methyl diazoacetate in the presence of copper-containing catalysts was studied. The product composition was found to depend on the reaction conditions and the nature and ratio of components of the catalytic system.
- Ivanova,Sultanova,Zlotskii
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experimental part
p. 106 - 108
(2011/06/18)
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- Oxidation of 5-hydroxymethylfurfural to maleic anhydride with molecular oxygen
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5-Hydroxymethylfurfural (HMF) was converted to maleic anhydride in 52% yield via selective oxidation with molecular oxygen using VO(acac)2 as catalyst in liquid phase. The Royal Society of Chemistry.
- Du, Zhongtian,Ma, Jiping,Wang, Feng,Liu, Junxia,Xu, Jie
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supporting information; experimental part
p. 554 - 557
(2011/05/11)
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- A selective Ru-catalyzed semireduction of alkynes to Z olefins under transfer-hydrogenation conditions
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By using a readily available, air- and moisture-stable dihydrido-Ru complex, a variety of Z olefins are accessible under transfer-hydrogenation conditions with formic acid as the hydrogen source in excellent yields and Z/E selectivities. A discerning transformation: Z-Configured C=C bonds are stereoselectively formed from alkynes in the presence of a Ru catalyst with formic acid as the sole H2 source at room temperature (see scheme). A variety of functional groups are compatible with this novel procedure. Operational simplicity and the lack of overreduction products are characteristics for this unprecedented process.
- Belger, Christian,Neisius, N. Matthias,Plietker, Bernd
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supporting information; experimental part
p. 12214 - 12220
(2011/03/17)
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- Resolution of 5-oxo-1-phenylpyrazolidine-3-carboxylic acid and synthesis of novel enantiopure amide derivatives
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The synthesis is reported of (±)-5-oxo-1-phenylpyrazolidine-3- carboxylic acid, (±)-3, via nucleophilic addition of phenylhydrazine to dimethyl maleate, followed by cyclization of the resulting hydrazine-diester. The resolution of (±)-3 was achieved via diastereomeric salts employing (R)- and (S)-a-methylbenzylamine as resolving agent. Preferential crystallization of the like (R,R)- and (S,S)- salts allowed the isolation of the desired enantiomerically pure (R)- and (S)- target compounds in up to 87-89 % of the theoretical yield. An X-ray structure of the (S,S)- salt allowed secure assignment of its relative configuration, and thus unequivocal assignment of the absolute configuration in the enantiomeric heterocycles.
- Melgar-Fernandez, Roberto,Gonzalez-Olvera, Rodrigo,Vargas-Caporali, Jorge,Perez-Isidoro, Rosendo,Juaristi, Eusebio
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experimental part
p. 55 - 75
(2010/09/03)
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- Role of the succinate skeleton in the disorder-order transition of AOT and its analogous molecules: Detection by infrared absorption spectra of the configurations arising from the difference in torsion angles of the succinate skeleton
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The IR spectra in the 13001450 cm-1 region, which reflect the CH and CH2 deformation vibrational modes of the succinate skeleton, have been investigated in detail for sodium dialkylsulfonates (alkyl groups: Ethyl, n-propyl, n-butyl, n-hexyl, n-heptyl, n-octyl, n-decyl, and n-dodecyl) and sodium 1,2-bis(2-ethylhexyl)sulfosuccinate (sodium 1,2-bis(2- ethylhexyloxycarbonyl)ethanesulfonate) (AOT). The results have provided clear evidence that two configurations, arising from the difference in the torsion angles of the succinate skeleton, are preferentially stabilized in aqueous solution as well as in the solid state, depending upon the concentration. Thus, the IR spectra of this region can be used as a powerful tool for elucidation of the mechanism of the disorderorder transition in aggregate systems of AOT or its homologs at the molecular level.
- Okabayashi, Hiro-Fumi,Izawa, Ken-Ichi,Sumiya, Akiko,Eastoe, Julian,O'Connor, Charmian J.
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experimental part
p. 651 - 659
(2010/08/08)
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- An easy one-pot procedure for the synthesis of N-sulfonyl phosphorous ylides and sulfonyl iminophosphoranes
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Reaction of triphenylphosphine and an electron deficient acetylenic ester in the presence of strong N-H acid such as alkyl and aryl sulfamides or acetamide produces phosphorous ylides at room temperature in CH 2Cl2. The aryl sulfamide phosphoranes undergo a smooth transformation reaction in boiling toluene and produce iminophosphoranes. Springer-Verlag 2007.
- Shaabani, Ahmad,Rahmati, Abbas,Naderi, Soheila
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p. 553 - 557
(2008/02/03)
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- Synthesis and activity studies of analogues of the rat selective toxicant norbormide
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Norbormide [5-(α-hydroxy-α-2-pyridylbenzyl)-7-(α-2-pyridylbenzylidene)-5-norbornene-2,3-dicarboximide] (NRB, 1), an existing but infrequently used rodenticide, is known to be uniquely toxic to rats but relatively harmless to other rodents and mammals. A series of NRB-related analogues were prepared to investigate the structural features responsible for, and the in vitro biological markers indicative of, in vivo lethality of the parent molecule in rats. Their synthesis and biological evaluation (vasoconstriction, vasodilation, mitochondrial dysfunction, cardiotoxicity and lethality) is described.
- Rennison, David,Bova, Sergio,Cavalli, Maurizio,Ricchelli, Fernanda,Zulian, Alessandra,Hopkins, Brian,Brimble, Margaret A.
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p. 2963 - 2974
(2008/02/01)
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- Selective monoesterification of malonic acid catalyzed by boric acid
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Boric acid catalyzes the monoesterification of malonic acid, likely through a chelation mechanism that is not available to the monoester product. Under more forcing conditions, diesters form to some extent, but conditions can be optimized to favour the monoester product (56?80%). With the easily handled solid acid catalyst, these reactions can be run with excess alcohol as solvent or with stoichiometric amounts of alcohol in acetonitrile with moderate heating. CSIRO 2007.
- Levonis, Stephan M.,Bornaghi, Laurent F.,Houston, Todd A.
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p. 821 - 823
(2008/03/12)
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- Semi-hydrogenation of alkynes using phosphinated polymer incarcerated (PI) palladium catalysts
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Phosphinated polymer incarcerated (PI) palladium catalysts prepared from a palladium(0) complex and phosphinated styrene-based polymers were found to show good selectivity in semi-hydrogenation of alkynes without strict control of H2 consumption. Moreover, these catalysts could be removed by simple filtration and without any leaching of Pd. The Royal Society of Chemistry 2006.
- Nishio, Ryo,Sugiura, Masaharu,Kobayashi, Shu
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p. 992 - 995
(2007/10/03)
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- A two-step four-component queuing cascade involving a Heck coupling, π-allylpalladium trapping and Diels-Alder reaction
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Palladium-catalyzed cross-coupling of bicyclopropylidene (1) with iodoethene (11) in the presence of a secondary amine 12 provides allylidenecyclopropanes 13 which undergo immediate Diels-Alder reactions upon addition of dienophiles 14-18 to provide 8-(1′-aminoethyl)-substituted spiro[2.5]oct-7-ene derivatives 23a-26a in 29-66% yield. The same one-pot, two-step queuing cascade can be carried out with other iodoalkenes including cyclic ones and with cyclic dienophiles such as N-arylmaleinamides 19-22 and N-phenyl-triazolinedione 37 to furnish highly substituted spiro[2.5]oct-4-enes and spirocyclopropanated heterobicycles 47a-49a, 41a-46a (17-50%). Spirocyclopropanated heterobicycles such as 55, 56 (25 and 38% yield, respectively) can also be obtained by an inter-intra-intra-intermolecular version of this queuing cascade involving 1-hydroxyethyl- and 1-aminoethyl-substituted iodoethenes 53, 54.
- Yücel, Baris,Arve, Lars,De Meijere, Armin
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p. 11355 - 11373
(2007/10/03)
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- Palladium-(N-heterocyclic carbene) hydrogenation catalysts
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(Chemical Equation Presented) Low-valent palladium compounds with N-heterocyclic carbenes (NHCs) formed from [Pd(NHC)(η2-alkene) 2] (see example) are amazingly selective catalysts for the hydrogenation of several alkynes to Z alkenes. One such complex, [Pd{1,3-(2,6-diethylphenyl)imidazol-2-ylidene}], has been employed for the selective (95%) hydrogenation of 1-phenyl-1-propyne to (Z)-1-phenyl-1-propene.
- Sprengers, Jeroen W.,Wassenaar, Jeroen,Clement, Nicolas D.,Cavell, Kingsley J.,Elsevier, Cornells J.
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p. 2026 - 2029
(2007/10/03)
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- PROCESS FOR THE PRODUCTION OF ESTERS OF MONO-,DI-OR POLYCARBOXYLIC ACIDS
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A process for the production of carboxylic acid esters by reaction of a carboxylic acid selected from mono-, di- and polycarboxylic acids, with an alcohol in the presence of water of solution comprising the steps of: (a) providing a solution comprising the carboxylic acid and the water of solution; (b) reacting the solution of the carboxylic acid in an esterification zone with an alcohol to form an ester and water of esterification; (c) removing the water of solution and the water of esterification; and (d) recovering the ester.
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Page/Page column 20-24
(2008/06/13)
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