623-50-7Relevant academic research and scientific papers
A continuous process for glyoxal valorisation using tailored Lewis-acid zeolite catalysts
Dapsens, Pierre Y.,Mondelli, Cecilia,Kusema, Bright T.,Verel, Rene,Perez-Ramirez, Javier
, p. 1176 - 1186 (2014)
The aqueous-phase heterogeneously catalysed isomerisation of bio-oil derived glyoxal is herein introduced as a novel route for the sustainable production of glycolic acid. While commercial ultra-stable Y zeolites displayed only moderate performance, their evaluation enabled us to highlight the crucial role of Lewis acidity in the reaction. Gallium incorporation into these zeolites boosted the glycolic acid yield, although the best catalytic results were obtained over tin-containing MFI-type zeolites, reaching 91% yield of the desired product at full conversion. These materials comprised hydrothermally-synthesised Sn-MFI as well as a novel catalyst obtained by the introduction of tin into silicalite-1 by means of a simpler and more scalable method, i.e. alkaline-assisted metallation. In-depth spectroscopic characterisation of these systems uncovered a substantial similarity of the tin centres obtained by the top-down and bottom-up synthetic approaches. NMR spectroscopic studies gave evidence that the reaction follows a 1,2-hydride shift mechanism solely catalysed by Lewis-acid sites. The Sn-MFI analogue could be reused in 5 cycles without the need for intermediate calcination, did not evidence any tin leaching, and demonstrated suitability for utilisation under continuous-flow operation. The tin-based zeolites exhibited remarkable performance also in alcoholic solvents, leading to the one-pot production of relevant alkyl glycolates.
Demethylative Alkylation of Methionine Residue by Employing the Sulfonium as the Key Intermediate
Chan, Albert S. C.,Ge, Yang,Hu, Qi-Long,Li, Jian,Liu, Jia-Tian,Song, Zhendong,Xiong, Xiao-Feng
supporting information, p. 8543 - 8548 (2021/11/13)
Methionine (Met) offers a valuable handle to achieve peptide chemical modification owing to its unique thioether functional group. In contrast with cysteine, the site-selective functionalization of the hydrophobic and redox-sensitive thioether motif on peptides is still challenging, and strategies for diversification on the Met residue are rarely disclosed. Herein we report a transition-metal-free and redox-neutral approach for Met diversification with substrate diversity, which could be applied to synthesize cyclic peptides.
Preparation method of levocetirizine
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Paragraph 0021-0022, (2020/04/17)
The invention provides a preparation method of levocetirizine. The method comprises the following steps of: the step 1, carrying out a cyclization reaction on (R)-4-chlorodiphenyl methylamine and tris(2-chloroethyl)amine to obtain a compound represented by a formula (I); 2, performing condensation reaction of the compound shown in the formula (I) and 2-ethyl glycolate to obtain a compound shown ina formula (II); and the step 3, converting the compound shown in the formula (II) into levocetirizine. According to the preparation method, (R)-4-chlorodiphenyl methylamine and tris(2-chloroethyl)amine are taken as the initial raw materials, and cyclization reaction, condensation reaction and hydrolysis reaction are carried out so as to obtain levocetirizine. The synthetic route provided by the invention is short, the yield is high, and experimental results show that the yield of the levocetirizine prepared by the method provided by the invention can reach 47%, and the purity can reach 99.7%.
A Reversible Liquid-to-Liquid Organic Hydrogen Carrier System Based on Ethylene Glycol and Ethanol
Zhou, Quan-Quan,Zou, You-Quan,Ben-David, Yehoshoa,Milstein, David
, p. 15487 - 15490 (2020/10/02)
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.
Preparation method of glycolic acid or glycolate
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Paragraph 0152-0154, (2020/09/20)
The invention discloses a preparation method of glycolic acid or glycolate. The method comprises the following steps of: formaldehyde and carbon monoxide are introduced into a reactor containing a reaction solution to carry out polymerization reaction, wherein the reaction solution contains an acid catalyst; after the relative molecular mass of a polymer generated by the polymerization reaction reaches 2,000 and above, the polymerization reaction system is cooled to crystallize and precipitate the generated polymer; solid-liquid separation is carried out on the material in the reactor; and excessive water or alcohol is added into the obtained solid phase to carry out a depolymerization reaction to obtain glycolic acid or glycolate. Compared with the prior art, the method disclosed by the invention is good in process stability, low in energy consumption, good in economic practicability and high in product yield, and has a very good application prospect.
Ru-Catalyzed Transfer Hydrogenation of Nitriles, Aromatics, Olefins, Alkynes and Esters
Alshakova, Iryna D.,Gabidullin, Bulat,Nikonov, Georgii I.
, p. 4860 - 4869 (2018/10/02)
This paper reports the preparation of new ruthenium(II) complexes supported by a pyrazole-phosphine ligand and their application to transfer hydrogenation of various substrates. These Ru complexes were found to be efficient catalysts for the reduction of nitriles and olefins. Heterocyclic compounds undergo transfer hydrogenation with good to moderate yields, affording examples of unusual hydrogenation of all-carbon-rings. Internal alkynes with bulky substituents show selective reduction to olefins with the unusual E–selectivity. Esters with strong electron-withdrawing groups can be reduced to the corresponding alcohols, if ethanol is used as the solvent. Possible mechanisms of hydrogenation and olefin isomerization are suggested on the basis of kinetic studies and labelling experiments.
Preparation method of chlorophenoxyacetic ester
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Paragraph 0064; 0065, (2019/01/08)
The invention provides a preparation method of chlorophenoxyacetic ester, wherein the preparation method comprises the following steps: A) carrying out reaction of glycolic acid and alcohol in tolueneto obtain glycolic ester; B) carrying out reaction of glycolic ester and metal alkoxide to obtain a metal salt of glycolic ester; and C) carrying out reaction of the metal salt of glycolic ester andchlorobenzene to obtain the chlorophenoxyacetic ester. The chlorophenoxyacetic ester is synthesized by condensation of chlorobenzene with the metal salt of glycolic ester, the use of chlorophenol withunpleasant odor is effectively avoided, the production of highly toxic dioxins is eliminated, and the product quality and the operating environment of the production site are greatly improved. Motherliquor containing effective ingredients cannot be produced, so the loss of effective ingredients is effectively avoided and the yield of the product is improved.
Silica-supported HClO4 promotes catalytic solvent- and metal-free O-H insertion reactions with diazo compounds
Gallo, Rafael Douglas C.,Burtoloso, Antonio C. B.
, p. 4547 - 4556 (2018/10/17)
Solvent-free O-H insertion reactions in the presence of diazo carbonyl compounds were carried-out in very mild conditions. Unlike the traditional metal-catalysed version, employing rhodium acetate dimer, this method uses eco-friendly silica-supported HClO4 as the catalyst. Only 0.3 mol% of this Br?nsted acid catalyst, that can also be recycled several times, is necessary to guarantee very good yields (up to 97%) in the O-H insertion reactions. Reaction set-up is simple and permitted the preparation of forty-three α-hydroxy and α-alkoxy esters/ketones in just 1 h and at room temperature.
ARTIFICIAL METALLOENZYMES CONTAINING NOBLE METAL-PORPHYRINS
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Paragraph 0338, (2018/11/21)
The present invention is drawn to artificial metalloenzymes for use in cyclopropanation reactions, amination and C—H insertion.
Generation and Reactivity of Electron-Rich Carbenes on the Surface of Catalytic Gold Nanoparticles
Oliver-Meseguer, Judit,Boronat, Mercedes,Vidal-Moya, Alejandro,Concepción, Patricia,Rivero-Crespo, Miguel ángel,Leyva-Pérez, Antonio,Corma, Avelino
supporting information, p. 3215 - 3218 (2018/03/13)
The reactive nature of carbenes can be modulated, and ultimately reversed, by receiving additional electron density from a metal. Here, it is shown that Au nanoparticles (NPs) generate an electron-rich carbene on surface after transferring electron density to the carbonyl group of an in situ activated diazoacetate, as assessed by Fourier transformed infrared (FT-IR) spectroscopy, magic angle spinning nuclear magnetic resonance (MAS NMR), and Raman spectroscopy. Density functional theory (DFT) calculations support the observed experimental values and unveil the participation of at least three different Au atoms during carbene stabilization. The surface stabilized carbene shows an extraordinary stability against nucleophiles and reacts with electrophiles to give new products. These findings showcase the ability of catalytic Au NPs to inject electron density in energetically high but symmetrically allowed valence orbitals of sluggish molecules.
