624-48-6Relevant articles and documents
Reactions of methoxycarbonylcarbene with 3-ethyl-2-phenyl- and 2,3-diphenyloxazolidines
Molchanov,Stepakov,Kopf,Zenkevich,Kostikov
, p. 2144 - 2148 (2001)
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
Long-lived 1H nuclear spin singlet in dimethyl maleate revealed by addition of thiols
Zhang, Yuning,Soon, Pei Che,Jerschow, Alexej,Canary, James W.
, p. 3396 - 3399 (2014)
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.
Bichromophoric Compounds. Photophysics and Photochemistry of (1-Naphthyl)alkyl Esters of Fumaric, Maleic, and Oxalic Acids
Holden, David A.,Gray, J. Bradley,McEwan, Ian
, p. 866 - 873 (1985)
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.
Cu(OAc)2-2,4-lutidine-ZnCl2 as an effective catalyst of functionalization of isobutylene oligomers and 1,2-polybutadiene with methyl diazoacetate
Gareev,Yangirov,Volodina,Sultanova,Biglova,Dokichev
, p. 1305 - 1309 (2009)
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
o-Fluoranil: Stereochemistry and mechanism of its Diels-Alder reactions
Lemal, David M.,Sang, Dayong,Ramanathan, Sudharsanam
, p. 7804 - 7811 (2009)
(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
Limits in Proton Nuclear Singlet-State Lifetimes Measured with para-Hydrogen-Induced Polarization
Zhang, Yuning,Duan, Xueyou,Soon, Pei Che,Canary, James W.,Jerschow, Alexej,Sychrovsky, Vladimír
, p. 2967 - 2971 (2016)
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).
Method for preparing diacid diester compound under catalysis of deep eutectic solvent
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Paragraph 0055-0058, (2021/05/19)
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.
Self-Assembled Open Porous Nanoparticle Superstructures
Liu, Rongjuan,Wei, Jingjing,Wei, Yanze,Yang, Zhijie,Zhang, Fenghua
supporting information, (2021/08/20)
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.
Chemical Reaction Monitoring using Zero-Field Nuclear Magnetic Resonance Enables Study of Heterogeneous Samples in Metal Containers
Blanchard, John W.,Budker, Dmitry,Burueva, Dudari B.,Eills, James,Garcon, Antoine,Koptyug, Igor V.,Kovtunov, Kirill V.,Picazo-Frutos, Román
, p. 17026 - 17032 (2020/07/30)
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.
A Br?nsted acidic, ionic liquid containing, heteropolyacid functionalized polysiloxane network as a highly selective catalyst for the esterification of dicarboxylic acids
Rajabi, Fatemeh,Wilhelm, Christian,Thiel, Werner R.
supporting information, p. 4438 - 4444 (2020/08/10)
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.
