- Phosphoric acid-modified commercial kieselguhr supported palladium nanoparticles as efficient catalysts for low-temperature hydrodeoxygenation of lignin derivatives in water
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Efficient production of high value-added chemicals and biofuels via low-temperature chemoselective HDO of lignin derivatives in water is still a challenge. Here, we construct a low-cost, active and stable Pd/PCE catalyst using phosphoric acid-modified commercial Celite (PCE) as the support, and this catalyst exhibits excellent activity in low-temperature HDO of vanillin as well as other lignin derivatives in water. The superior catalytic performance is due to the presence of P species on the surface of Pd/PCE, accelerating the selective conversion of the intermediate into the final product. Detailed experimental and mechanistic studies reveal that the rapid conversion of the intermediate to the final product proceeds via a free-radical process in an interfacial microenvironment created by intimate interacting between the P species and Pd NPs. The insights of this work provide a new low-cost catalytic system for efficient production of valuable chemicals and future biofuels from lignin derivatives. This journal is
- Cui, Yuntong,Liu, Zhaohui,Ran, Jiansu,Wang, Jianjian,Yangcheng, Ruixue
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p. 1570 - 1577
(2022/03/14)
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- Highly efficient Meerwein-Ponndorf-Verley reductions over a robust zirconium-organoboronic acid hybrid
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The Meerwein-Ponndorf-Verley (MPV) reaction is an attractive approach to selectively reduce carbonyl groups, and the design of advanced catalysts is the key for these kinds of interesting reactions. Herein, we fabricated a novel zirconium organoborate using 1,4-benzenediboronic acid (BDB) as the precursor for MPV reduction. The prepared Zr-BDB had excellent catalytic performance for the MPV reduction of various biomass-derived carbonyl compounds (i.e., levulinate esters, aldehydes and ketones). More importantly, the number of borate groups on the ligands significantly affected the catalytic activity of the Zr-organic ligand hybrids, owing to the activation role of borate groups on hydroxyl groups in the hydrogen source. Detailed investigations revealed that the excellent performance of Zr-BDB was contributed by the synergetic effect of Zr4+and borate. Notably, this is the first work to enhance the activity of Zr-based catalysts in MPV reactions using borate groups.
- Song, Jinliang,Hua, Manli,Huang, Xin,Visa, Aurelia,Wu, Tianbin,Fan, Honglei,Hou, Minqiang,Zhang, Zhaofu,Han, Buxing
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p. 1259 - 1265
(2021/02/26)
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- Unusual transformation of 4-hydroxy/methoxybenzylic alcohols via C[sbnd]C ipso-substitution reaction using proton-exchanged montmorillonite as media
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We present here proton-exchanged montmorillonite-mediated an unusual transformation of 4-hydroxy and 4-methoxybenzylic alcohols to form symmetrical benzylic ethers and diarylmethanes under mild conditions. Nuclear magnetic resonance spectroscopy and density functional theory calculations support a plausible mechanism, which includes a distinctive aromatic C[sbnd]C ipso-substitution reaction with a hydroxymethyl group as the C-based leaving group.
- Chen, Dongyin,Chen, Xuan,Dong, Zezhong,Jiang, Nan,Li, Fei,Yun, Yangfang,Zhou, Yu
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supporting information
(2020/11/12)
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- Polypyridyl iridium(III) based catalysts for highly chemoselective hydrogenation of aldehydes
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Iridium-catalyzed transfer hydrogenation (TH) of carbonyl compounds using HCOOR (R = H, Na, NH4) as a hydrogen source is a pivotal process as it provides the clean process and is easy to execute. However, the existing highly efficient iridium catalysts work at a narrow pH; thus, does not apply to a wide variety of substrates. Therefore, the development of a new catalyst which works at a broad pH range is essential as it can gain a broader scope of utilization. Here we report highly efficient polypyridyl iridium(III) catalysts, [Ir(tpy)(L)Cl](PF6)2 {where tpy = 2,2′:6′,2′'-Terpyridine, L = phen (1,10-Phenanthroline), Me2phen (4,7-Dimethyl-1,10-phenanthroline), Me4phen (3,4,7,8-Tetramethyl-1,10-phenanthroline), Me2bpy (4,4′-Dimethyl-2–2′-dipyridyl)} for the chemoselective reduction of aldehydes to alcohols in aqueous ethanol and sodium formate as the hydride source. The reaction can be carried out efficiently in broad pH ranges, from pH 6 to 11. These catalysts are air stable, easy to prepare using commercially available starting materials, and are highly applicable for a wide range of substrates, such as electron-rich or deficient (hetero)arenes, halogens, phenols, alkoxy, ketones, esters, carboxylic acids, cyano, and nitro groups. Particularly, acid and hydroxy groups containing aldehydes were reduced successfully in basic and acidic reaction conditions, demonstrating the efficiency of the catalyst in a broad pH range with high conversion rates under microwave irradiation.
- Pandrala, Mallesh,Resendez, Angel,Malhotra, Sanjay V.
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p. 283 - 288
(2019/09/30)
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- Thioether type compound as well as synthesis method and application thereof
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The invention provides a thioether type compound and also relates to a synthesis method of the thioether type compound and application of the thioether type compound. A chemical structure of the thioether type compound enables the thioether type compound to have a relatively high melting point and be not easily sublimated, so that the thioether type compound has relatively good thermal stability;the thioether type compound has an excellent anti-oxidization capability and has no toxic and side effects, so that the thioether type compound has relatively high utilization safety; secondly, a target compound is synthesized by the synthesis method of the thioether type compound, provided by the invention, by adopting one-step reaction; visibly, the synthesis method is simple to operate, moderate in technological conditions, green and environmentally friendly, and is very suitable for large-scale industrial production. A series of experiments prove that the thioether type compound has an obvious inhibition effect on oxidization of various foods and an anti-oxidization effect of the compound has a certain dose-effect relationship with the concentration of the compound; therefore, the thioether type compound provided by the invention has a wide application prospect and a good market potential.
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Paragraph 0056-0059
(2018/09/13)
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- CSJ acting as a versatile highly efficient greener resource for organic transformations
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Simple, new, greener and efficient alternatives to the existing protocols have been developed for the reduction of aromatic aldehydes to their corresponding alcohols, decarboxylation of substituted benzoic acids (C6-C1) and substituted cinnamic acids (C6-C3) with a hydroxyl group at the para position with respect to the acid group to corresponding phenolic compounds and vinyl phenols respectively by using a natural feedstock, cucumber juice (CSJ), which acts as a greener solvent system, performing a substrate-selective reaction. Additionally, the hydrolysis of the acetyl as well as the benzoyl group of aromatic compounds has been carried out to afford excellent yield by CSJ.
- Maity, Himadri Sekhar,Misra, Kaushik,Mahata, Tanushree,Nag, Ahindra
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p. 24446 - 24450
(2016/03/15)
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- Synthesis and antioxidant activities of 3,5-dialkoxy-4-hydroxycinnamamides
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A series of 3,5-dialkoxy-4-hydroxycinnamamides 6 and 7 was synthesized, and their antioxidant activity was assessed using the thiobarbituric acid reactive substance (TBARS) assay. Interestingly, cinnamamides with longer alkoxy groups on the C-3 and C-5 positions display enhanced inhibition, and most of the compounds in the series tested exhibit excellent lipid peroxidation inhibitory activities. Some cinamamides bearing hexyloxy or 2,6-di-tert-butyl-4-methyl phenol groups have submicromolar inhibitory activities.
- Kang, Tae-Souk,Jo, Hyang-Ok,Park, Woo-Kyu,Kim, Jong-Pyung,Konishi, Yasuo,Kong, Jae-Yang,Park, No-Sang,Jung, Young-Sik
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p. 1663 - 1667
(2008/12/21)
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- Biotransformation of sinapic acid by the green algae Stichococcus bacillaris 155LTAP and Ankistrodesmus braunii C202.7a
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Sinapic acid was bioconverted by the green alga Stichococcus bacillaris into 4-hydroxy-3,5-dimethoxybenzoic acid, 4-hydroxy-3,5-dimethoxybenzaldehyde and 4-hydroxy-3,5-dimethoxybenzylic alcohol. Incubation of sinapic acid in a culture of the alga Ankistrodesmus braunii gave 3,6-dihydroxy-2,4-dimethoxy-7H-benzocyclohepten-7-one, a new compound formed by bioconversion of thomasidioic acid, the primary oxidative product of sinapic acid.
- DellaGreca, Marina,Pinto, Gabriele,Pollio, Antonino,Previtera, Lucio,Temussi, Fabio
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p. 2779 - 2780
(2007/10/03)
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- Fourier transform Raman assignment of guaiacyl and syringyl marker bands for lignin determination
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A near infrared fourier transform Raman (NIR-FTR) spectroscopic technique was utilized to characterize lignin in wood. The Raman bands for C=C stretching derived from 4-hydroxy-3-methoxyphenyl (guaiacyl) nuclei and from 3,5-dimethoxy-4-hydroxyphenyl (syringyl) nuclei exist independently. The NIR-FTR analysis of a series of lignin model compounds indicated that a syringyl band was shifted to a lower frequency compared to a guaiacyl band. This shift was also observed in chemically synthesized lignin (DHP). Syringyl DHP, in which all the aromatic nuclei consist of syringyl type, exhibited a C=C stretching band at 1594 cm-1, while guaiacyl DHP exhibited the band at 1599 cm-1. These bands were designated as syringyl and guaiacyl marker bands, respectively. Chemical and physical treatment of hardwood and softwood exhibited different characteristics. One of the reasons is the chemical structure of lignin. Softwood mainly contains only guaiacyl lignin, while hardwood contains both guaiacyl and syringyl lignin, and the syringyl/guaiacyl (S/G) ratio varies among species. Under high-resolution conditions (1 cm-1), the NIR-FTR spectra of 10 hardwoods (wood meal samples) revealed that both syringyl and guaiacyl marker bands existed. On the other hand, the spectra of softwoods contained only a guaiacyl marker bands existed. On the other hand, the spectra of softwoods contained only a guaiacyl marker band. The S/G ratio in hardwood calculated from the peak area intensity ratio of two marker bands shows a linear relationship with the S/G ratio obtained from conventional nitrobenzene oxidation analysis with the correlation factor > 0.96. Furthermore, if peak component separation analysis was combined, low-resolution spectral data gave a similar S/G ratio. Either syringyl of guaiacyl marker bands can be assigned in the NIR-FTR spectra of wood blocks (saw-cut surface). This spectral technique may provide an easy-handling and non-destructive analytical method for lignin determination.
- Takayama, Miyuki,Johjima, Toru,Yamanaka, Takeshi,Wariishi, Hiroyuki,Tanaka, Hiroo
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p. 1621 - 1628
(2007/10/03)
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- Synthesis of 1,2-dihydronaphthalenes and spiro[4.5]-deca-3,6,9-trien-8-ones from benzylic alcohols
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The synthesis of 1,2-dihydronaphthalenes and spiro[4.5]decatrienones via reaction of an allenyl-silane and a benzylic cation is reported.
- Angle,Arnaiz
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p. 2327 - 2330
(2007/10/02)
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- Electron-Transfer Reactions in Pulping Systems. 5. Application of an Intramolecular Cyclization Reaction as a Detector of the Formation of Quinonemethide Radical Anions
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Compound 6, which incorporates a hex-5-enyl group on a quinonemethide precursor, has been synthesized and reacted in 1 M NaOH at 135 deg C in the presence of various pulping additives.Reduction of 6 either prior to or after cyclization to a five-membered ring provides evidence that a quinonemethide radical anion intermediate had formed.Some additives such as anthrahydroquinone and glucose were effective electron-transfer agents for the probe quinonemethide, while others such as sodium sulfide and sulfite were ineffective.The probe, therefore, provides information on the nature of chemical reactions that may be occurring during the pulping of wood.Anthrahydroquinone and glucose provided significantly different amounts of cyclized products.Glucose gave high yields of cyclized products, including three unique tricyclo2,7>dodecatrienes.Apparently glucose reduces the radical intermediates relatively slowly, providing time for cyclization to occur.With no additives, other than 1 M NaOH, and long reaction times, the probe compound 6 provided some cyclized products; the electron-transfer agent in this case presumably is a phenolate ion.
- Smith, Dean A.,Dimmel, Donald R.
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p. 5428 - 5434
(2007/10/02)
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- Process for producing alkylphenols
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There is disclosed a process for producing an alkylphenol comprising reacting a phenol with an aldehyde and hydrogen in the presence of (a) an alkaline or alkaline earth metal catalyst selected from a hydroxide of an alkaline metal, hydroxide of an alkaline earth metal, a carbonate of an alkaline metal, and a hydrogencarbonate of an alkaline metal and (b) a hydrogenation catalyst. By the use of the process, the alkylphenols can be produced in good yield in one stage method.
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- Process for producing alkylphenols
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There is disclosed a process for producing an alkylphenol comprising reacting a phenol with an aldehyde and hydrogen in the presence of (a) an alkaline or alkaline earth metal catalyst selected from a hydroxide of an alkaline metal, hydroxide of an alkaline earth metal, a carbonate of an alkaline metal, and a hydrogencarbonate of an alkaline metal and (b) a hydrogenation catalyst. By the use of the process, the alkylphenols can be produced in good yield in one stage method.
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- BENZYL ETHERS OF METHYL α-D-GLUCOPYRANOSIDE
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Methyl 4-O-(3-methoxy-4-hydroxybenzyl) and methyl 4-O-(3,5-dimethoxy-4-hydroxybenzyl)-α-D-glucopyranoside and their 6-O-isomers were prepared as model substances for the ether lignin-saccharide bond by reductive cleavage of corresponding 4,6-O-benzylidene derivatives.Kinetic study of acid-catalyzed hydrolysis of the compounds prepared was carried out by spectrophotometric determination of the benzyl alcoholic groups set free, after their reaction with quinonemonochloroimide, and it showed the low stability of the p-hydroxybenzyl ether bond.
- Joniak, Dusan,Kosikova, Bozena,Kosakova, Ludmila
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p. 1959 - 1963
(2007/10/02)
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