758-12-3Relevant articles and documents
Kinetic understanding using NMR reaction profiling
Susanne, Flavien,Smith, David S.,Codina, Anna
, p. 61 - 64 (2012)
The combination of kinetic understanding and reaction modeling has been successfully applied to the development of processes from laboratory to manufacturing plant. Although extensively used in bulk chemistry, polymers, and the oil industry [ Bayer Technology Services, http://www.bayertechnology.cn/ uploads/media/0707-e-300dpi.pdf, July 2011; Lawrence Livermore National Laboratory, http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit-review-2011/ fuel-technologies/ft010-pitz-2 011-o.pdf,July 2011; Shin, S. B.; Han, S. P.; Lee, W. J.; Chae, J. H.; Lee, D. I.; Lee, W. H.; Urban, Z.Hydrocarbon Process. 2007, April) 83; Baumer, C.; Urban, Z.Hydrocarbon Process. 2007, June) 71 ], it has not been exploited to its full potential in the pharmaceutical industry. We present a fast and efficient methodology for kinetic modeling of chemical reactions using 1H NMR reaction monitoring that can be used for the process understanding and development of active pharmaceutical ingredients. The parameters that are important for the development of a good, reliable model for the prediction and optimization of reaction conditions are discussed. The hydrolysis of acetic anhydride was chosen to illustrate the methodology because it is mechanistically and kinetically well established.
Efficient generation of an oxidopyrylium ylide using a Pd catalyst and its [5+2] cycloadditions with several dipolarophiles
Suga, Hiroyuki,Iwai, Taichi,Shimizu, Masahiro,Takahashi, Kie,Toda, Yasunori
, p. 1109 - 1112 (2018)
An efficient method for the generation of an oxidopyrylium ylide from 6-acetoxy-6-acetoxymethyl-2H-pyran-3(6H)-one using a Pd catalyst and [5+2] cycloadditions of the resulting ylide are described. Among substituted styrene derivatives as dipolarophiles, electron-rich styrenes showed higher yield (up to 80%). The [5+2] cycloaddition reactions can also be applied to exo-methylene cyclic compounds, and an improved method for the synthesis of polygalolide intermediate has been demonstrated.
One-pot synthesis of microporous and mesoporous (NH4) 3PW12O40 by reaction of in-situ generated PW12O403- with NH4+ in a strongly acidic solution
Sahiro, Koichi,Ide, Yusuke,Sano, Tsuneji,Sadakane, Masahiro
, p. 4157 - 4162 (2013)
A simple synthesis of microporous and micro/meso bimodal porous (NH 4)3PW12O40 by reaction of in-situ generated [PW12O40]3- with NH4 + in a strongly acidic
Late-Stage β-C(sp3)-H Deuteration of Carboxylic Acids
Mal, Sourjya,Uttry, Alexander,Van Gemmeren, Manuel
supporting information, p. 10895 - 10901 (2021/08/03)
Carboxylic acids are highly abundant in bioactive molecules. In this study, we describe the late-stage β-C(sp3)-H deuteration of free carboxylic acids. On the basis of the finding that C-H activation with our catalysts is reversible, the de-deuteration process was first optimized. The resulting method uses ethylenediamine-based ligands and can be used to achieve the desired deuteration when using a deuterated solvent. The reported method allows for the functionalization of a wide range of free carboxylic acids with diverse substitution patterns, as well as the late-stage deuteration of bioactive molecules and related frameworks and enables the functionalization of nonactivated methylene β-C(sp3)-H bonds for the first time.
Stepwise Iodide-Free Methanol Carbonylation via Methyl Acetate Activation by Pincer Iridium Complexes
Yoo, Changho,Miller, Alexander J. M.
supporting information, p. 12633 - 12643 (2021/08/23)
Iodide is an essential promoter in the industrial production of acetic acid via methanol carbonylation, but it also contributes to reactor corrosion and catalyst deactivation. Here we report that iridium pincer complexes mediate the individual steps of methanol carbonylation to methyl acetate in the absence of methyl iodide or iodide salts. Iodide-free methylation is achieved under mild conditions by an aminophenylphosphinite pincer iridium(I) dinitrogen complex through net C-O oxidative addition of methyl acetate to produce an isolable methyliridium(III) acetate complex. Experimental and computational studies provide evidence for methylation via initial C-H bond activation followed by acetate migration, facilitated by amine hemilability. Subsequent CO insertion and reductive elimination in methanol solution produced methyl acetate and acetic acid. The net reaction is methanol carbonylation to acetic acid using methyl acetate as a promoter alongside conversion of an iridium dinitrogen complex to an iridium carbonyl complex. Kinetic studies of migratory insertion and reductive elimination reveal essential roles of the solvent methanol and distinct features of acetate and iodide anions that are relevant to the design of future catalysts for iodide-free carbonylation.
Highly efficient visible-light photocatalytic ethane oxidation into ethyl hydroperoxide as a radical reservoir
Zhu, Yao,Fang, Siyuan,Chen, Shaoqin,Tong, Youjie,Wang, Chunling,Hu, Yun Hang
, p. 5825 - 5833 (2021/05/07)
Photocatalytic ethane conversion into value-added chemicals is a great challenge especially under visible light irradiation. The production of ethyl hydroperoxide (CH3CH2OOH), which is a promising radical reservoir for regulating the oxidative stress in cells, is even more challenging due to its facile decomposition. Here, we demonstrated a design of a highly efficient visible-light-responsive photocatalyst, Au/WO3, for ethane oxidation into CH3CH2OOH, achieving an impressive yield of 1887 μmol gcat?1in two hours under visible light irradiation at room temperature for the first time. Furthermore, thermal energy was introduced into the photocatalytic system to increase the driving force for ethane oxidation, enhancing CH3CH2OOH production by six times to 11?233 μmol gcat?1at 100 °C and achieving a significant apparent quantum efficiency of 17.9% at 450 nm. In addition, trapping active species and isotope-labeling reactants revealed the reaction pathway. These findings pave the way for scalable ethane conversion into CH3CH2OOH as a potential anticancer drug.
Production of Pure Aqueous13C-Hyperpolarized Acetate by Heterogeneous Parahydrogen-Induced Polarization
Kovtunov, Kirill V.,Barskiy, Danila A.,Shchepin, Roman V.,Salnikov, Oleg G.,Prosvirin, Igor P.,Bukhtiyarov, Andrey V.,Kovtunova, Larisa M.,Bukhtiyarov, Valerii I.,Koptyug, Igor V.,Chekmenev, Eduard Y.
supporting information, p. 16446 - 16449 (2016/11/09)
A supported metal catalyst was designed, characterized, and tested for aqueous phase heterogeneous hydrogenation of vinyl acetate with parahydrogen to produce13C-hyperpolarized ethyl acetate for potential biomedical applications. The Rh/TiO2catalyst with a metal loading of 23.2 wt % produced strongly hyperpolarized13C-enriched ethyl acetate-1-13C detected at 9.4 T. An approximately 14-fold13C signal enhancement was detected using circa 50 % parahydrogen gas without taking into account relaxation losses before and after polarization transfer by magnetic field cycling from nascent parahydrogen-derived protons to13C nuclei. This first observation of13C PHIP-hyperpolarized products over a supported metal catalyst in an aqueous medium opens up new possibilities for production of catalyst-free aqueous solutions of nontoxic hyperpolarized contrast agents for a wide range of biomolecules amenable to the parahydrogen induced polarization by side arm hydrogenation (PHIP-SAH) approach.
Degradation of 2,5-dihydroxy-1,4-benzoquinone by hydrogen peroxide: A combined kinetic and theoretical study
Hosoya, Takashi,Rosenau, Thomas
, p. 3176 - 3182 (2013/07/04)
2,5-Dihydroxy-1,4-benzoquinone (DHBQ) is one of the key chromophores formed upon aging in cellulosic materials. This study addresses the degradation mechanism of DHBQ by hydrogen peroxide to provide a solid knowledge base for optimization of bleaching sequences aiming at DHBQ removal. Kinetic analysis provided an activation energy (Ea) of 20.4 kcal/mol. Product analyses indicated the product mixture to contain malonic acid, acetic acid, and carbon dioxide. DFT(B3LYP) computation presented a plausible mechanism for the formation of these products from DHBQ. DHBQ forms intermediate I2k, having an intramolecular O-O bridge between C-2 and C-5 of the 1,4-cyclohexadione structure. This O-O bond is homolytically cleaved, and the subsequent β-fragmentation of the resulting radical forms ketene and oxaloacetic acid. While ketene yields acetic acid, oxaloacetic acid then gives malonic acid and carbon dioxide through further attack of hydrogen peroxide via an intermediate that is oxidatively decarboxylated. The calculated Ea value (23.3 kcal/mol) in the rate-determining step, i.e., the homolysis of I2k, agreed well with the experimental value. There is also a minor pathway in which the spin state changes to triplet during the homolysis of I2k; in this way two malonyl radicals are formed that are converted to two molecules of malonic acid.
Oxidative functionalization of methane in the presence of a homogeneous rhodium-copper-chloride catalytic system: Transformation of acetic and propionic acids as solvent components
Chepaikin,Bezruchenko,Menchikova,Moiseeva,Gekhman,Moiseev
scheme or table, p. 133 - 142 (2012/01/13)
The oxidative functionalization of methane (O2, CO, 95°C, Rh III/CuI, II/Cl- catalytic system) was studied in an aqueous acetic or propionic acid medium. It was shown that oxidative decarbonylation of carboxylic acids takes place along with methanol and methyl carboxylate formation.
