7022-92-6Relevant academic research and scientific papers
Parahydrogen-Induced Polarization in Hydrogenation Reactions Mediated by a Metal-Free Catalyst
Chernichenko, Konstantin,Repo, Timo,Sorochkina, Kristina,Telkki, Ville-Veikko,Yang, Shengjun,Zakharov, Danila O.,Zhivonitko, Vladimir V.
, (2022/01/22)
We report nuclear spin hyperpolarization of various alkenes achieved in alkyne hydrogenations with parahydrogen over a metal-free hydroborane catalyst (HCAT). Being an intramolecular frustrated Lewis pair aminoborane, HCAT utilizes a non-pairwise mechanism of H2 transfer to alkynes that normally prevents parahydrogen-induced polarization (PHIP) from being observed. Nevertheless, the specific spin dynamics in catalytic intermediates leads to the hyperpolarization of predominantly one hydrogen in alkene. PHIP enabled the detection of important HCAT-alkyne-H2 intermediates through substantial 1H, 11B and 15N signal enhancement and allowed advanced characterization of the catalytic process.
Generation of a Sulfinamide Species from Facile N-O Bond Cleavage of Nitrosobenzene by a Thiolate-Bridged Diiron Complex
Xu, Sunlin,Yang, Dawei,Wang, Baomin,Chen, Yifeng,Ye, Shengfa,Qu, Jingping
, p. 17374 - 17387 (2021/10/25)
The activation of nitrosobenzene promoted by transition-metal complexes has gained considerable interest due to its significance for understanding biological processes and catalytic C-N bond formation processes. Despite intensive studies in the past decades, there are only limited cases where electron-rich metal centers were commonly employed to achieve the N-O or C-N bond cleavage of the coordinated nitrosobenzene. In this regard, it is significant and challenging to construct a suitable functional system for examining its unique reactivity toward reductive activation of nitrosoarene. Herein, we present a {Fe2S2} functional platform that can activate nitrosobenzene via an unprecedented iron-directed thiolate insertion into the N-O bond to selectively generate a well-defined diiron benzenesulfinamide complex. Furthermore, computational studies support a proposal that in this concerted four-electron reduction process of nitrosobenzene the iron center serves as an important electron shuttle. Notably, compared to the intact bridging nitrosoarene ligand, the benzenesulfinamide moiety has priority to convert into aniline in the presence of separate or combined protons and reductants, which may imply the formation of the sulfinamide species accelerates reduction process of nitrosoarene. The reaction pattern presented here represents a novel activation mode of nitrosobenzene realized by a thiolate-bridged diiron complex.
Structures of silver nitrate complexes with quinolines according to NMR data
Sakharov,Kovalev,Gorbunova, Yu. E.,Tokmakov,Skabitskii,Kokunov, Yu. V.
, p. 75 - 81 (2017/03/01)
Silver(I) nitrate complexes [AgNO3(L)2], where L is quinoline or 2-, 4-, and 8-methylquinoline, are synthesized and studied by the multinuclear NMR (1H, 13C, 15N) method in acetonitrile. The influence
A stable isotope labeling prohibited pigment synthesis method
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Paragraph 0069; 0070; 0076; 0077, (2017/10/13)
The invention relates to a synthesizing method for a prohibited pigment labeled by a stable isotope. According to the synthesizing method, bromobenzene labeled by a stable isotope D or 13C is aminated and sulfonated to synthesize an intermediate sodium sulfanilate labeled by the stable isotope D or 13C, or the bromobenzene is taken as the raw materials and then aminated and sulfonated with an ammoniation reagent labeled by a stable isotope 15 N to synthesize the intermediate sodium sulfanilate labeled by the stable isotope 15N, and then diazotizing and coupling are performed to synthesize the prohibited pigment labeled by the stable isotope D or 15N or 13C. Compared with the prior art, the synthesizing method has the advantages that the process route is simple, the prohibited pigment labeled by the stable isotope is easy to synthesize, the product is easy to separate and purify, the chemical purity of the product is more than 99.0 percent, the isotope abundance is more than 98.0 percent, the requirements of trace detection in the field of food safety can be fully met, and the good economical efficiency and use value are achieved.
Study of the Beckmann rearrangement of acetophenone oxime over porous solids by means of solid state NMR spectroscopy
Fernandez, Ana Belen,Lezcano-Gonzalez, Ines,Boronat, Mercedes,Blasco, Teresa,Corma, Avelino
experimental part, p. 5134 - 5141 (2011/06/21)
The Beckmann rearrangement of acetophenone oxime using zeolite H-beta and silicalite-N as catalysts has been investigated by means of 15N and 13C solid state NMR spectroscopy in combination with theoretical calculations. The results obtained show that the oxime is N-protonated at room temperature on the acid sites of zeolite H-beta. At reaction temperatures of 423 K or above, the two isomeric amides, acetanilide and N-methyl benzamide (NMB) are formed, and interact with the Bronsted acid sites of zeolite H-beta through hydrogen bonds. The presence of residual water hydrolyzes the two amides, while larger amounts inhibit the formation of NMB and cause the total hydrolysis of the acetanilide. Over siliceous zeolite silicalite-N, containing silanol nests as active sites, the oxime is adsorbed through hydrogen bonds and only acetanilide is formed at reaction temperatures of 423 K or above. In the presence of water, the reaction starts at 473 K, still being very selective up to 573 K, and the amide is partially hydrolyzed only above this temperature. the Owner Societies 2009.
Chloroaniline/lignin conjugates as model system for nonextractable pesticide residues in crop plants
Lange, B. Markus,Hertkorn, Norbert,Sandermann Jr., Heinrich
, p. 2113 - 2118 (2007/10/03)
In vitro lignins formed by the peroxidase/H2O2-mediated polymerization of coniferyl alcohol in the presence of 3,4-dichloroaniline or [15N]aniline were studied by 1H, 13C, and 15N NMR spectroscopy. The anilines were >95% bound to the benzylic α-position of lignin side chains. Mild acid hydrolysis under simulated stomach conditions (0.1 M HCl, 37 °C) was studied as a first estimate of animal bioavailability. The two extremes of facile or slow acid hydrolysis that are known for chloroaniline/lignin complexes could be reproduced by using low or high incorporation ratios of aniline to coniferyl alcohol (10 or 40 mol %, respectively). The case of facile acid hydrolysis and high animal bioavailability may be due to the high mole ratios used and may not be relevant for pesticidal crop plant residue levels of 3,4- dichloroaniline. The latter are typically in the parts per million range. On the basis of 15N NMR spectral fine structure, we propose that the acid- labile linkage may be due to anchimeric assistance in conformers formed at the high aniline molar ratio. The optimized methods presented here allow the use of in vitro lignin copolymers as a reference system for the structural features and the bioavailability of nonextractable pesticide residues in crop plants. In vitro lignins formed by the peroxidase/H2O2-mediated polymerization of coniferyl alcohol in the presence of 3,4-dichloroaniline or [15N]aniline were studied by 1H,13C, and 15N NMR spectroscopy. The anilines were >95% bound to the benzylic α-position of lignin side chains. Mild acid hydrolysis under simulated stomach conditions (0.1 M HCl, 37 °C) was studied as a first estimate of animal bioavailability. The two extremes of facile or slow acid hydrolysis that are known for chloroaniline/lignin complexes could be reproduced by using low or high incorporation ratios of aniline to coniferyl alcohol (10 or 40 mol %, respectively). The case of facile acid hydrolysis and high animal bioavailability may be due to the high mole ratios used and may not be relevant for pesticidal crop plant residue levels of 3,4-dichloroaniline. The latter are typically in the parts per million range. On the basis of 15N NMR spectral fine structure, we propose that the acid-labile linkage may be due to anchimeric assistance in conformers formed at the high aniline molar ratio. The optimized methods presented here allow the use of in vitro lignin copolymers as a reference system for the structural features and the bioavailability of nonextractable pesticide residues in crop plants.
Effect of Molecular Motion and Solvent Interactions on Nitrogen-15 Relaxation in Anilines
Lambert, Joseph B.,Daniel Stec, III
, p. 301 - 307 (2007/10/02)
Dipolar relaxation of 15N in anilines and anilinium ions is influenced by overall motion of the molecule, by rotation about the aryl-nitrogen bond, by inversion of the aniline nitrogen and by interactions of the NH2 or NH3+ group with the solve
