2503-46-0Relevant articles and documents
Molybdate Stabilized Magnesium‐Iron Hydrotalcite Materials: Potential Catalysts for Isoeugenol to Vanillin and Olefin Epoxidation
Neethu, P. P.,Sakthivel, A.,Sreenavya, A.
, (2021/08/03)
A series of molybdate-intercalated and stabilized magnesium‐iron hydrotalcite (HMFeMo) materials with different molybdate loadings were successfully prepared by an in-situ hydrothermal method. The prepared HMFeMo materials were systematically characterized using Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), Ultraviolet-visible spectroscopy, scanning electron microscopy, thermo-gravimetric analysis, nitrogen adsorption-desorption and X-ray photoelectron spectroscopy (XPS) experiments. The XRD results demonstrated the successful intercalation of molybdate ions in the interlayer space of magnesium-iron hydrotalcite and the stabilization of the layered structure. In addition, the XPS spectra of the HMFeMo materials revealed the presence of molybdenum in a higher-valent oxidation state. The calcination of HMFeMo materials led to the formation of solid solution of mixed metal oxides. Both the as-prepared and calcined HMFeMo catalysts showed promising activity for the epoxidation of cyclooctene, as a model reaction. Furthermore, the performance of the as-prepared and calcined HMFeMo catalysts for the oxidation of a biomass model compound, namely isoeugenol to vanillin, was evaluated. The isoeugenol conversion over the as-prepared HMFeMo catalysts under solvent-free conditions and using tertiary-butyl hydroperoxide in decane as the oxidant was good. Moreover, the isoeugenol conversion and selectivity toward vanillin of HMFeMo0.1, with a molybdate loading of 0.1 mol %, were the highest (86.2% and 83.1%, respectively) of all HMFeMo catalysts in this study at 80 °C for 5 hr. HMFeMo0.1 presented the best catalytic activity for both the epoxidation of cyclooctene and oxidation of isoeugenol to vanillin, and its activity remained unchanged after several runs.
Continuous flow study of isoeugenol to vanillin: A bio-based iron oxide catalyst
Filiciotto, Layla,Márquez-Medina, María Dolores,Pineda, Antonio,Balu, Alina M.,Romero, Antonio A.,Angelici, Carlo,de Jong, Ed,van der Waal, Jan C.,Luque, Rafael
, p. 281 - 290 (2019/12/25)
The use of a biorefinery co-product, such as humins, in combination with an iron precursor in a solvent-free method yields a catalytic material with potential use in selective oxidative cleavage reactions. In particular, this catalyst was found active in the hydrogen-peroxide assisted oxidation of a naturally extracted molecule, isoeugenol, to high added-value flavouring agent, vanillin. By carrying out the reaction in continuous flow, not only a better understanding of the reaction mechanism and of the catalyst deactivation can be achieved, but also important insights for optimised conditions can be developed. The findings of this paper could pave the way to a more sustainable process for the production of a valuable food and perfume additive, vanillin.
Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment
Cheng, Xi-Chuang,Guo, Xin-Ran,Liu, Hua-Min,Liu, Yu-Lan,Qin, Zhao,Wang, Xue-De
, p. 4348 - 4358 (2020/09/22)
Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4′ linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry.
MnO2as a terminal oxidant in Wacker oxidation of homoallyl alcohols and terminal olefins
Fernandes, Rodney A.,Ramakrishna, Gujjula V.,Bethi, Venkati
, p. 6115 - 6125 (2020/10/27)
Efficient and mild reaction conditions for Wacker-type oxidation of terminal olefins of less explored homoallyl alcohols to β-hydroxy-methyl ketones have been developed by using a Pd(ii) catalyst and MnO2 as a co-oxidant. The method involves mild reaction conditions and shows good functional group compatibility along with high regio- and chemoselectivity. While our earlier system of PdCl2/CrO3/HCl produced α,β-unsaturated ketones from homoallyl alcohols, the present method provided orthogonally the β-hydroxy-methyl ketones. No overoxidation or elimination of benzylic and/or β-hydroxy groups was observed. The method could be extended to the oxidation of simple terminal olefins as well, to methyl ketones, displaying its versatility. An application to the regioselective synthesis of gingerol is demonstrated.
Stereoselective Synthesis of 1-Arylpropan-2-amines from Allylbenzenes through a Wacker-Tsuji Oxidation-Biotransamination Sequential Process
González-Martínez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
, p. 2582 - 2593 (2019/05/15)
Herein, a sequential and selective chemoenzymatic approach is described involving the metal-catalysed Wacker-Tsuji oxidation of allylbenzenes followed by the amine transaminase-catalysed biotransamination of the resulting 1-arylpropan-2-ones. Thus, a series of nine optically active 1-arylpropan-2-amines were obtained with good to very high conversions (74–92%) and excellent selectivities (>99% enantiomeric excess) in aqueous medium. The Wacker-Tsuji reaction has been exhaustively optimised searching for compatible conditions with the biotransamination experiments, using palladium(II) complexes as catalysts and iron(III) salts as terminal oxidants in aqueous media. The compatibility of palladium/iron systems for the chemical oxidation with commercially available and made in house amine transaminases was analysed, finding ideal conditions for the development of a general and stereoselective cascade sequence. Depending on the selectivity displayed by selected amine transaminase, it was possible to produce both 1-arylpropan-2-amines enantiomers under mild reaction conditions, compounds that present therapeutic properties or can be employed as synthetic intermediates of chiral drugs from the amphetamine family. (Figure presented.).
Method for preparing medical intermediate 4-hydroxy-3-methoxyphenylacetone
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Paragraph 0029-0036, (2018/06/15)
The invention discloses a method for preparing a medical intermediate 4-hydroxy-3-methoxyphenylacetone. The method comprises steps as follows: firstly, a catalyst containing graphene, zirconia and Ptis prepared, 2-methoxy-4-(2-nitro-1-allyl) phenol is prepared from vanillic aldehyde and nitroethane as raw materials under the catalysis of glacial acetic acid and n-butylamine, and 2-methoxy-4-(2-oximido propyl) phenol is prepared from 2-methoxy-4-(2-nitro-1-allyl) phenol as a reaction raw material by adding ammonium formate and the self-made catalyst through stirring reaction; finally, 2-methoxy-4-(2-oximido propyl) phenol and a sulfuric acid solution are subjected to the stirring reaction for 1-3 h at the room temperature, after the reaction, a reaction liquid is left to stand for layering, a xylene layer is separated out and dried with anhydrous sodium sulfate, a solvent is removed through reduced-pressure concentration, fractions at 150-151 DEG C are collected, and 4-hydroxy-3-methoxyphenylacetone is obtained. The method is simple to operate, purity of a target product is high, yield is high, and cost is low.
Benign-by-design preparation of humin-based iron oxide catalytic nanocomposites
Filiciotto, Layla,Balu, Alina M.,Romero, Antonio A.,Rodríguez-Castellón, Enrique,Van Der Waal, Jan C.,Luque, Rafael
, p. 4423 - 4434 (2017/09/27)
The current acid-catalyzed conversion of biomass feedstocks yields substantial quantities of undesired by-products called humins, for which applications are yet to be found. This work aims to provide a starting point for valorisation of humins via preparation of humin-based iron oxide catalytic nanocomposites from humins and thermally treated humins (foams) via solvent-free methodologies including ball milling and thermal degradation. The prepared materials were found to be active in the microwave-assisted selective oxidation of isoeugenol (conversions >87%) to vanillin, proving the feasibility to use humin by-products as template/composite materials.
Correlating lignin structural features to phase partitioning behavior in a novel aqueous fractionation of softwood Kraft black liquor
Stoklosa, Ryan J.,Velez, Julian,Kelkar, Shantanu,Saffron, Christopher M.,Thies, Mark C.,Hodge, David B.
supporting information, p. 2904 - 2912 (2013/10/08)
In this work, a set of softwood lignins were recovered from a Kraft black liquor using a novel pH-based fractionation process involving sequential CO 2 acidification and separation of the solvated aqueous lignin fraction. These recovered lignin fractions were characterized with respect to properties that may be responsible for their phase partitioning behavior as well as properties that may render the lignins more suitable for materials applications. Lignin fractions were recovered between a pH range of 12.8 and 9.5 with the bulk of the lignin (90%) recovered between a pH of 11.1 and 10.0. While all the fractions were found to consist primarily of lignin as validated by sample methoxyl content, the first fractions to phase separated were found to be especially enriched in aliphatic extractives and polysaccharides. From the bulk of the lignin that was recovered between a pH of 11.1 and 10.0 a number of noteworthy trends were discernible from the data. Specifically, the phenolic hydroxyl content was found to exhibit a strong negative correlation to the fractionation pH and exhibited a nearly 50% increase with recovery at decreasing pH, while the GPC-estimated molecular weights and 13C NMR-estimated β-O-4 content showed strong positive correlations to the pH at recovery. The aliphatic hydroxyl content exhibited minimal differences between recovery conditions. Overall, these results suggest that this fractionation approach can generate lignin fractions enriched in select physical or structural properties that may be important for their application as feedstocks for renewable chemicals or materials.
DEPOLYMERIZATION OF LIGNIN USING SOLID ACID CATALYSTS
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Page/Page column 6; 7, (2012/12/13)
The invention provides for a process for the depolymerization of lignin in an inert atmosphere to result in substituted phenolic monomer compounds. The process is catalysed by heterogeneous solid acid catalysts and is carried out in batch or continuous mode.
Oxidation of isoeugenol to vanillin by the "h2O 2-vanadate-pyrazine-2-carboxylic acid" reagent
Gusevskaya, Elena V.,Menini, Luciano,Parreira, Luciana A.,Mesquita, Rafaela A.,Kozlov, Yuriy N.,Shul'Pin, Georgiy B.
, p. 140 - 147,8 (2020/08/20)
Isoeugenol [2-methoxy-4-(prop-1-en-1-yl)phenol; compound 1] can be oxidized to vanillin (4-hydroxy-3-methoxybenzaldehyde, compound 2) by H 2O2 in the presence of the n-Bu4NVO 3/pyrazine-2-carboxylic acid catalyt
