- Production of Plant Phthalate and its Hydrogenated Derivative from Bio-Based Platform Chemicals
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Direct transformation of bio-based platform chemicals into aromatic dicarboxylic acids and their derivatives, which are widely used for the manufacture of polymers, is of significant importance for the sustainable development of the plastics industry. However, limited successful chemical processes have been reported. This study concerns a sustainable route for the production of phthalate and its hydrogenated derivative from bio-based malic acid and erythritol. The key Diels–Alder reaction is applied to build a substituted cyclohexene structure. The dehydration reaction of malic acid affords fumaric acid with 96.6 % yield, which could be used as the dienophile, and 1,3-butadiene generated in situ through erythritol deoxydehydration serves as the diene. Starting from erythritol and dibutyl fumarate, a 74.3 % yield of dibutyl trans-4-cyclohexene-1,2-dicarboxylate is obtained. The palladium-catalyzed dehydrogenation of the cycloadduct gives a 77.8 % yield of dibutyl phthalate. Dibutyl trans-cyclohexane-1,2-dicarboxylate could be formed in nearly 100 % yield under mild conditions by hydrogenation of the cycloadduct. Furthermore, fumaric acid and fumarate, with trans configurations, were found to be better dienophiles for this Diels–Alder reaction than maleic acid and maleate, with cis configuration, based on the experimental and computational results. This new route will pave the way for the production of environmental friendly plastic materials from plants.
- Lu, Rui,Lu, Fang,Si, Xiaoqin,Jiang, Huifang,Huang, Qianqian,Yu, Weiqiang,Kong, Xiangtao,Xu, Jie
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- An efficient and practical system for the catalytic oxidation of alcohols, aldehydes, and α,β-unsaturated carboxylic acids
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(Chemical Equation Presented) Upon exposure to commercial bleach (～5% aqueous sodium hypochlorite), nickel(II) chloride or nickel(II) acetate is transformed quantitatively into an insoluble nickel species, nickel oxide hydroxide. This material consists of high surface area nanoparticles (ca. 4 nm) and is a useful heterogeneous catalyst for the oxidation of many organic compounds. The oxidation of primary alcohols to carboxylic acids, secondary alcohols to ketones, aldehydes to carboxylic acids, and α,β- unsaturated carboxylic acids to epoxy acids is demonstrated using 2.5 mol % of nickel catalyst and commercial bleach as the terminal oxidant. We demonstrate the controlled and selective oxidation of several organic substrates using this system affording 70-95% isolated yields and 90-100% purity. In most cases, the oxidations can be performed without an organic solvent, making this approach attractive as a "greener" alternative to conventional oxidations.
- Grill, Joseph M.,Ogle, James W.,Miller, Stephen A.
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- TAN-1323 C and D, new concanamycin-group antibiotics; Detection of the angiostatic activity with a wide range of macrolide antibiotics
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We detected potent angiostatic activity in a MrOH extract from the mycelia of microbial strain S-45628 in the chick chorioallantoic membrane (CAM) assay. The producer was taxonomically characterized as Streptomyces purpurascens. Active principles designated TAN-1323 A~D were isolated and determined to be 18-membered macrolide antibiotics; components C and D are new members of this group, while components A and B are identical to concansmycins C and A, respectively. When tested in the CAM assay, components B and D gave huge avascular zones at the extremely low doses of 10~100ng/disk, although components A and C showed far weaker activity due to their preferential tissue-damaging effect on the CAM. The discovery that these 18-membered macrolide antibiotics are angiostatic substances prompted us to examine other types of macrolide antibiotics, leading to the discovery that 18-membered macrolide antibiotics such as bafilomycin C1, tylosin and leucomycin also show angiostatic activity on the CAM. Thus, angiostatic potential is widely distributed among macrolide antibiotics. The mechanism of action of these macrolide antibiotics is also discussed.
- Ishii,Hida,Iinuma,Muroi,Nozaki
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- Potent covalent inhibitors of bacterial urease identified by activity-reactivity profiling
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Covalent enzyme inhibitors constitute a highly important group of biologically active compounds, with numerous drugs available on the market. Although the discovery of inhibitors of urease, a urea hydrolyzing enzyme crucial for the survival of some human pathogens, is a field of medicinal chemistry that has grown in recent years, covalent urease inhibitors have been rarely investigated until now. Forty Michael acceptor-type compounds were screened for their inhibitory activities against bacterial urease, and several structures exhibited high potency in the nanomolar range. The correlation between chemical reactivity towards thiols and inhibitory potency indicated the most valuable compound — acetylenedicarboxylic acid, with Ki?=42.5 nM and logkGSH=-2.14. Molecular modelling studies revealed that acetylenedicarboxylic acid is the first example of highly effective mode of binding based on simultaneous bonding to a cysteine residue and interaction with nickel ions present in the active site. Activity-reactivity profiling of reversible covalent enzyme inhibitors is a general method for the identification of valuable drug candidates.
- Macegoniuk, Katarzyna,Kowalczyk, Rafa?,Rudzińska, Anna,Psurski, Mateusz,Wietrzyk, Joanna,Berlicki, ?ukasz
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- Purification and characterization of a lyase from the EDTA-degrading bacterial strain DSM 9103 that catalyzes the splitting of [S,S]-ethylenediaminedisuccinate, a structural isomer of EDTA
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The bacterial strain DSM 9103, able to utilize EDTA as a sole source of carbon, nitrogen, and energy, is also capable to grow with [S,S]-ethylenediaminedisuccinate ([S,S]-EDDS), a structural isomer of EDTA. In cell-free extracts of [S,S]-EDDS-grown bacteria, [S,S]-EDDS degradation was observed in the absence of any cofactors. An enzyme was purified 41-fold that catalyzed the non-hydrolytic splitting of [S,S]-EDDS leading to the formation of fumarate and N-(2-aminoethyl) aspartic acid. These data strongly suggest that the enzyme belongs to the group of carbon-nitrogen lyases. The splitting reaction was reversible, and an equilibrium constant of approximately 43.0 10-1 M was determined. Out of the three stereo-isomers of EDDS, [S,S]- and [R,S]-EDDS were accepted as substrates by the lyase, whereas [R,R]-EDDS remained unchanged in assays with both cell-free extracts and pure enzyme. The enzyme catalyzed the transformation of free [S,S]-EDDS and of [S,S]-EDDS-metal complexes with stability constant lower than 10, namely of MgEDDS, CaEDDS, BaEDDS and to a small extent also of MnEDDS; Fe(III)EDDS, NiEDDS, CuEDDS, CoEDDS and ZnEDDS were not transformed.
- Witschel, Margarete,Egli, Thomas
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- Structural and kinetic studies on adenylosuccinate lyase from Mycobacterium smegmatis and Mycobacterium tuberculosis provide new insights on the catalytic residues of the enzyme
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Adenylosuccinate lyase (ASL), an enzyme involved in purine biosynthesis, has been recognized as a drug target against microbial infections. In the present study, ASL from Mycobacterium smegmatis (MsASL) and Mycobacterium tuberculosis (MtbASL) were cloned, purified and crystallized. The X-ray crystal structure of MsASL was determined at a resolution of 2.16 A. It is the first report of an apo-ASL structure with a partially ordered active site C3 loop. Diffracting crystals of MtbASL could not be obtained and a model for its structure was derived using MsASL as a template. These structures suggest that His149 and either Lys285 or Ser279 of MsASL are the residues most likely to function as the catalytic acid and base, respectively. Most of the active site residues were found to be conserved, with the exception of Ser148 and Gly319 of MsASL. Ser148 is structurally equivalent to a threonine in most other ASLs. Gly319 is replaced by an arginine residue in most ASLs. The two enzymes were catalytically much less active compared to ASLs from other organisms. Arg319Gly substitution and reduced flexibility of the C3 loop might account for the low catalytic activity of mycobacterial ASLs. The low activity is consistent with the slow growth rate of Mycobacteria and their high GC containing genomes, as well as their dependence on other salvage pathways for the supply of purine nucleotides.
- Banerjee, Sanchari,Agrawal, Monika J.,Mishra, Diptimayee,Sharan, Siddharth,Balaram, Hemalatha,Savithri, Handanhal S.,Murthy, Mathur R. N.
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- Microflow photochemistry - A reactor comparison study using the photochemical synthesis of terebic acid as a model reaction
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The continuous-microflow photochemical synthesis of terebic acid from maleic acid was investigated in two different microreactor set-ups. The results were subsequently compared to analogue experiments in a conventional chamber reactor. Based on conversion rates, reactor design and energy efficiency calculations, the simple microcapillary reactor showed the best overall performance.
- Aida, Shin,Terao, Kimitada,Nishiyama, Yasuhiro,Kakiuchi, Kiyomi,Oelgem?ller, Michael
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- Mechanism of the Enzymic Elimination of Ammonia from 3-Substituted Aspartic Acids by 3-Methylaspartase
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Kinetic experiments with 3-methylaspartase, using aspartic, 3-methylaspartic, and 3-ethylaspartic acid and the appropriate C-3 deuteriated isotopomers as substrates, reveal that C(3)-H bond cleavage is partially rate-limiting for 3-methylaspartic acid, much less rate-limiting for 3-ethylaspartic acid, and not rate-limiting at all for aspartic acid.
- Botting, Nigel P.,Akhtar, Mahmoud,Cohen, Mark A.,Gani, David
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- The 3-methylaspartase reaction probed using 2H- and 15N-Isotope effects for three substrates: A flip from a concerted to a carbocationic amino-enzyme elimination mechanism upon changing the C-3 stereochemistry in the substrate from R to S
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The mechanisms of the elimination of ammonia from (2S,3S)-3-methylaspartic acid, (2S)-aspartic acid and (2S,3R)-3-methylaspartic acid, catalysed by the enzyme l-threo-3-methylaspartase ammonia-lyase (EC 4.3.1.2) have been probed using 15N-isotope effects. The 15N-isotope effects for V/K for both (2S,3S)-3-methylaspartic acid and aspartic acid are 1.0246±0.0013 and 1.0390±0.0031, respectively. The natural substrate, (2S,3S)-3-methylaspartic acid, is eliminated in a concerted fashion such that the C(β)-H and C(α)-N bonds are cleaved in the same transition state. (2S)-Aspartic acid appears to follow the same mechanistic pathway, but deprotonation of the conjugate acid of the base for C-3 is kinetically important and influences the extent of 15N-fractionation. (2S,3R)-3-Methylaspartic acid is deaminated via a stepwise carbocationic mechanism. Here we elaborate on the proposed model for the mechanism of methylaspartase and propose that a change in stereochemistry of the substrate induces a change in the mechanism of ammonia elimination. Copyright (C) 1999 Elsevier Science B.V.
- Gani, David,Archer, Catherine H.,Botting, Nigel P.,Pollard, John R.
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- ELIMINATION OF HYDROGEN FLUORIDE FROM FLUORINATED SUCCINIC ACIDS.(II) KINETICS OF DEHYDROFLUORINATION OF FLUORO-, 2,2-DIFLUORO-, MESO- AND DL-2,3-DIFLUORO-, AND TRIFLUOROSUCCINIC ACIDS
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Elimination of hydrogen fluoride from fluorosuccinic acid gave fumaric acid, from 2,2-difluorosuccinic acid, meso- and DL-2,3-difluorosuccinic acid fluorofumaric acid, and dehydrofluorination of trifluorosuccinic acid afforded difluoromaleic acid.Kinetic data based on 1H NMR measurements are presented for temperatures of 60 deg C, 75 deg C and 90 deg C.All the dehydrofluorinations follow second order kinetics.Activation energies for the dehydrofluorination of the above acids were found to be: 19.3, 17.3, 18.8, 17.9 and 18.3 kcal, respectively.Since both diastereomeric 2,3-difluorosuccinic acids give fluorofumaric acid as the only product of dehydrofluorination, one of them (DL) undergoes trans elimination while the other (meso) must undergo cis elimination.
- Hudlicky, M.,Glass, T. E.
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- On chemical reactions in the laser-induced breakdown of a liquid
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It is shown experimentally that a laser-induced breakdown of a liquid is accompanied by chemical reactions initiated by radicals and excited species formed in the spark. It is found that, in water, the laser-induced breakdown is accompanied by the dissociation of water and dissolved nitrogen molecules with the formation of HNO2 and HNO3, while, in a FeSO 4 aqueous solution, by the Fe2+ → Fe3+ oxidation reaction. It is assumed that the mechanism of the process is analogous to that of the action of ionizing radiations and the chemical action of ultrasonically induced cavitation (it is proposed that this mechanism of chemical action of a laser-induced spark proposed be termed indirect). Energy yields of these reactions are found to be of the same order of magnitude as for sonochemical redox reactions. It is shown that the laser-induced breakdown of an aqueous solution of maleic acid is accompanied by its stereoisomerization into fumaric acid, a process catalyzed by small amounts of an alkyl bromide. It is established that, for the formation of fumaric acid in a laser-induced spark, the energy yield is about five orders of magnitude higher than that typical of the above-mentioned redox reactions in the laser-induced spark. Nauka/Interperiodica 2006.
- Margulis,Ovchinnikov,Margulis
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- Asymmetric Synthesis of (S)- and (R)-Malic Acid from Ketene and Chloral
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Quinidine (5) catalyzes the addition of ketene (1) to chloral (2) at -50 deg C in toluene.The β-(trichloromethyl)-β-propiolactone 3 is formed virtually optically pure (98percent enantiomeric excess).A mechanism for this reaction, accounting for the high enantiomeric excess, is proposed.Known hydrolytic procedures convert the lactone 3 to malic acid (6).By proper choice of catalyst both (R)- and (S)-malic acid can be obtained optically pure.
- Wynberg, Hans,Staring, Emiel G. J.
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- N-terminal truncation of a maleate cis-trans isomerase from Rhodococcus jostii RHA1 results in a highly active enzyme for the biocatalytic production of fumaric acid
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As part of the project to develop an efficient biocatalytic process for the production of fumaric acid, a full-length putative maleate cis-trans isomerase gene from Rhodococcus jostii RHA1 was synthesized and expressed in Escherichia coli Rosetta2 (DE3) pLysS, but the protein was not soluble and showed no catalytic activity. Bioinformatics analysis of the protein sequence indicated that there were two hydrophilic and two hydrophobic amino acid clusters in an alternate arrangement at the N-terminus, and 50 extra amino acid residues at the N-terminus were not present in the known maleate cis-trans isomerases. The alternate hydrophilic and hydrophobic clusters at the N-terminus were thus truncated one by one to evaluate their effect on the gene expression and enzyme activity. Three mutants (MaiR-D41/42-304AA, MaiR-D48/49-304AA and MaiR-D52/53-304AA) without the hydrophilic and hydrophobic clusters were expressed as soluble protein with maleate cis-trans isomerase activity. Among them, MaiR-D48 was purified and its properties were studied. The purified enzyme had a temperature optimum of 40 C and a wide pH range (5.0-9.0) with the optimum pH being 8.0. The whole cells of E. coli expressing MaiR-D48 catalyzed the isomerization of maleic acid to fumaric acid at 1 M substrate concentration, showing its potential for industrial use.
- Liu, Xiangtao,Zhao, Qing,Ren, Jie,Dong, Wenyue,Wu, Qiaqing,Zhu, Dunming
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- Mechanism of 3-methylaspartase probed using deuterium and solvent isotope effects and active-site directed reagents: Identification of an essential cysteine residue
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The mechanism of the l-threo-3-methylaspartate ammonia-lyase (EC 4.3.1.2) reaction has been probed using deuterium and solvent isotope effects with three different substrates, (2S,3S)-3-methylaspartic acid, (2S)-aspartic acid and (2S,3R)-3-methylaspartic acid. Each substrate appears to form a covalent adduct with the enzyme through the amination of a dehydroalanine (DehydAla-173) residue. The true substrates are N-protonated and at low pH, the alkylammonium groups are deprotonated internally in a closed solvent-excluded pocket after K+ ion, an essential cofactor, has become bound to the enzyme. At high pH, the amino groups of the substrates are able to react with the dehydroalanine residue prior to K+ ion binding. This property of the system gives rise to complex kinetics at pH 9.0 or greater and causes the formation of dead-end complexes which lack Mg2+ ion, another essential cofactor. The enzyme-substrate adduct is subsequently deaminated in two elimination processes. Hydrazines act as alternative substrates in the reverse reaction direction in the presence of fumaric acid derivatives, but cause irreversible inhibition in their absence. Borohydride and cyanide are not inhibitors. N-Ethylmaleimide also irreversibly inactivates the enzyme and labels residue Cys-361. The inactivation process is enhanced in the presence of cofactor Mg2+ ions and Cys-361 appears to serve as a base for the removal of the C-3 proton from the natural substrate, (2S,3S)-3-methylaspartic acid. The dehydroalanine residue appears to be protected in the resting form of the enzyme by generation of an internal thioether cross-link. The binding of the substrate and K+ ion appear to cause a conformational change which requires hydroxide ion. This is linked to reversal of the thioether protection step and generation of the base for substrate deprotonation at C-3. The deamination reaction displays high reverse reaction commitments and independent evidence from primary deuterium isotope effect data indicates that a thiolate acts as the base for deprotonation at C-3. Copyright (C) 1999 Published by Elsevier Science Ltd.
- Pollard, John R.,Richardson, Susan,Akhtar, Mahmoud,Lasry, Philippe,Neal, Tracy,Botting, Nigel P.,Gani, David
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- Poly (4-vinylpyridine) catalyzed isomerization of maleic acid to fumaric acid
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Fumaric acid is an important industrial intermediate compound that is mostly produced by isomerization of maleic acid under the catalysis of thiourea. In this study, a solid catalyst, poly (4-vinylpyridine) resin, was firstly used instead of thiourea for the catalytic isomerization of maleic acid because of its ease of separation and reusability. A high isomerization conversion rate of 86% was obtained for 100 mL of 200 mg/L maleic acid solution with resin dosage of 0.1 g under 353 K. This high isomerization conversion was due to the high nucleophilicity of PVP molecules. The optimum pH of 1.5 was determined by the degree of ionization of maleic acid. In the kinetics study, the conversion of maleic acid exhibited a second-order kinetic equation with apparent activation energy of 226.06 kJ/mol. Furthermore, the regenerated resin demonstrated no loss of catalytic activity. The excellent catalytic performance and high recyclability suggest that PVP resin has promising application in the isomerization of maleic acid to fumaric acid.
- Li, Qiang,Tao, Weihua,Li, Aimin,Zhou, Qing,Shuang, Chendong
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- Study on the Isomerization of Maleic Acid to Fumaric Acid without Catalyst
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Fumaric acid is an important food additive and industrial intermediate compound. The traditional methods of producing fumaric acid were catalyzed by maleic acid isomerization. In this study, isomerization of maleic acid in water without catalyst was inves
- Gao, Zhuo,Chen, Wangmi,Chen, Xiaoting,Wang, Dali,Yi, Shouzhi
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- The Structure of Chalybaeizanic Acid and Quaesitic Acid, Two New Lichen Depsidones Related to Salazinic Acid
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The depsidones chalybaeizanic acid (1,4,10-trihydroxy-8-methyl-3,7-dioxo-1,3-dihydro-7H-isobenzofuro[4,5-b][1,4]benzodioxepin-5,11-dicarbaldehyde) (4) and quaesitic acid (11-formyl-1,4,10-trihydroxy-8-methyl-3,7-dioxo-1,3-dihydro-7H-isobenzofuro[4,5-b][1,4]benzodioxepin-5-methyl hydrogen fumarate) (5) have been isolated from the lichens Xanthoparmelia amphianthoides and Hypotrachyna quaesita respectively, and their structures determined by a combination of spectroscopic evidence, partial synthesis, derivatization or degradation reactions.
- Elix, John A.,Wardlaw, Judith H.
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- Oxidation of aliphatic side chains in anthracene Diels-Alder adducts
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An efficient oxidation of methyl and primary side chains of anthracene Diels Alder adducts with KMnO4 is reported. The oxidation leaves the bridgehead methines intact providing Diels-Alder adducts of anthracenecarboxylic acids. Retro Diels-Alder reaction allows for the preparation of the parent anthracenecarboxylic acids.
- McCormick, Frankie A.,Marquardt, Donald J.
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- A covalent succinylcysteine-like intermediate in the enzyme-catalyzed transformation of maleate to fumarate by maleate isomerase
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Maleate isomerase (MI), a member of the Asp/Glu racemase superfamily, catalyzes cis-trans isomerization of the C2-C3 double bond in maleate to yield fumarate. Mutational studies, in conjunction with the structure of the C194A mutant of Nocardia farcinica MI cocrystallized with maleate, have revealed an unprecedented mode of catalysis for the superfamily in which the isomerization reaction is initiated by nucleophilic attack of cysteine at the double bond, yielding a covalent succinylcysteine-like intermediate.
- Fisch, Florian,Fleites, Carlos Martinez,Delenne, Marie,Baudendistel, Nina,Hauer, Bernhard,Turkenburg, Johan P.,Hart, Sam,Bruce, Neil C.,Grogan, Gideon
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- Purification and characterization of fumarase from Corynebacterium glutamicum
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Fumarase (EC 4.2.1.2) from Corynebacterium glutamicum (Brevibacterium flavum) ATCC 14067 was purified to homogeneity. Its amino-terminal sequence (residues 1 to 30) corresponded to the sequence (residues 6 to 35) of the deduced product of the fumarase gene of C. glutamicum (GenBank accession no. BAB98403). The molecular mass of the native enzyme was 200 kDa. The protein was a homotetramer, with a 50-kDa subunit molecular mass. The homotetrameric and stable properties indicated that the enzyme belongs to a family of Class II fumarase. Equilibrium constants (Keq) for the enzyme reaction were determined at pH 6.0, 7.0, and 8.0, resulting in Keq = 6.4, 6.1, and 4.6 respectively in phosphate buffer and in 16, 19, and 17 in non-phosphate buffers. Among the amino acids and nucleotides tested, ATP inhibited the enzyme competitively, or in mixed-type, depending on the buffer. Substrate analogs, meso-tartrate, D-tartrate, and pyromellitate, inhibited the enzyme competitively, and D-malate in mixed-type.
- Genda, Tomoko,Watabe, Shoji,Ozaki, Hachiro
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- Pompon Dahlia-like Cu2O/rGO Nanostructures for Visible Light Photocatalytic H2 Production and 4-Chlorophenol Degradation
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Hierarchical Cu2O nanospheres with a Pompon Dahlia-like morphology were prepared by a one-pot synthesis employing electrostatic self-assembly. Nanocomposite analogues were also prepared in the presence of reduced graphene oxide (rGO). Photophysical properties of the hierarchical Cu2O nanospheres and Cu2O/rGO nanocomposite were determined, and their photocatalytic applications evaluated for photocatalytic 4-chlorophenol (4-CP) degradation and H2 production. Introduction of trace (2O for H2 production from 2.23 % to 3.35 %, giving an increase of evolution rate from 234 μmol.g?1.h?1 to 352 μmol.g?1.h?1 respectively. The AQE for 4-CP degradation also increases from 52 % to 59 %, with the removal efficiency reaching 95 % of 10 ppm 4-CP within 1 h. Superior performance of the hierarchical Cu2O/rGO nanocomposite is attributable to increased visible light absorption, reflected in a greater photocurrent density. Excellent catalyst photostability for >6 h continuous reaction is observed.
- Karthikeyan, Sekar,Ahmed, Kassam,Osatiashtiani, Amin,Lee, Adam F.,Wilson, Karen,Sasaki, Keiko,Coulson, Ben,Swansborough-Aston, Will,Douthwaite, Richard E.,Li, Wei
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- Characterization of the cross-linked structure of fumarate-based degradable polymer networks
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A new method was developed to examine networks formed with linear macromers of fumaric acid and diacrylate cross-linking agents in order to analyze their cross-linked structure. This method involved the accelerated degradation of the networks and the analysis of the degradation products. Two model networks of poly(propylene fumarate) (PPF) cross-linked with poly(propylene fumarate)-diacrylate (PPF-DA) and oligo(poly(ethylene glycol) fumarate) (OPF) cross-linked with poly(ethylene glycol)-diacrylate (PEG-DA) were evaluated with this method to determine the macromer and cross-linking agent conversions, the network cross-linking density, and an estimate of the molecular weight between crosslinks. The validity of the method was confirmed by the analysis of the composition of the un-cross-linked macromers and the correlation of the mechanical properties of the cross-linked polymers with the macromer/cross-linking agent double bond ratio. The results showed that acrylate species had participated more than fumarates in network formation. Furthermore, the structure of PPF/PPF-DA networks was influenced by the amount of cross-linking agent in the polymer formulation, and the OPF/PEG-DA network structure was controlled by the number of repeating fumarate units in the macromer. This method provides a new means to characterize the macromolecular structure of fumarate-based networks.
- Timmer, Mark D.,Jo, Seongbong,Wang, Chuanyue,Ambrose, Catherine G.,Mikos, Antonios G.
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- Size-Dependent Visible Light Photocatalytic Performance of Cu2O Nanocubes
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Well-defined Cu2O nanocubes with tunable dimensions and physicochemical properties have been prepared using a simple one-pot reaction. Reduction of Cu(II) salts by ascorbic acid in the presence of PEG as a structure-directing agent affords crystalline Cu2O nanocubes of between 50 to 500 nm. Optical band gap, band energies, charge-carrier lifetimes and surface oxidation state systematically evolve with nanocube size, and correlate well with visible light photocatalytic activity for aqueous phase phenol degradation and H2 production which are both directly proportional to size (doubling between 50 and 500 nm). HPLC reveals fumaric acid as the primary organic product of phenol degradation, and selectivity increases with nanocube size at the expense of toxic catechol. Apparent quantum efficiencies reach 26 % for phenol photodegradation and 1.2 % for H2 production using 500 nm Cu2O cubes.
- Karthikeyan, Sekar,Kumar, Santosh,Durndell, Lee J.,Isaacs, Mark A.,Parlett, Christopher M. A.,Coulson, Ben,Douthwaite, Richard E.,Jiang, Zhi,Wilson, Karen,Lee, Adam F.
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- Ionic liquids breakdown by Fenton oxidation
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Fenton oxidation has proved to be an efficient treatment for the degradation of ionic liquids (ILs) of different families viz. imidazolium, pyridinium, ammonium and phosphonium, in water. The intensification of the process, defined as the improvement on the efficiency of H2O2 consumption, by increasing the temperature is necessary to avoid high reaction times and the need of large excess of H2O2. In this work, temperatures within the range of 70-90°C have been used, which allowed an effective breakdown of the ILs tested (1 g L-1 initial concentration) with the stoichiometric amount of H2O2 and a relatively low Fe3+dose (50 mg L-1). Under these conditions conversion of the ILs was achieved in less than 10 min, with TOC reductions higher than 60% upon 4 h reaction time, except for the phosphonium IL. The remaining TOC corresponded mainly to short-chain organic acids. The treatment reduced substantially the ecotoxicity up to final values below 0.01 TU in most cases and a significant improvement of the biodegradability was achieved. Upon Fenton oxidation of the four ILs tested hydroxylated compounds of higher molecular weight than the starting ILs, fragments of ILs partially oxidized and short-chain organic acids were identified as reaction by-products. Reaction pathways are proposed.
- Munoz, Macarena,Domínguez, Carmen M.,De Pedro, Zahara M.,Quintanilla, Asunción,Casas, Jose A.,Rodriguez, Juan J.
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- Ordered mesoporous carbon as an efficient heterogeneous catalyst to activate peroxydisulfate for degradation of sulfadiazine
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Catalytic potential of carbon nanomaterials in peroxydisulfate (PDS) advanced oxidation systems for degradation of antibiotics remains poorly understood. This study revealed ordered mesoporous carbon (type CMK) acted as a superior catalyst for heterogeneous degradation of sulfadiazine (SDZ) in PDS system, with a first-order reaction kinetic constant (k) and total organic carbon (TOC) mineralization efficiency of 0.06 min?1 and 59.67% ± 3.4% within 60 min, respectively. CMK catalyzed PDS system exhibited high degradation efficiencies of five other sulfonamides and three other types of antibiotics, verifying the broad-degradation capacity of antibiotics. Under neutral pH conditions, the optimal catalytic parameters were an initial SDZ concentration of 44.0 mg/L, CMK dosage of 0.07 g/L, and PDS dosage of 5.44 mmol/L, respectively. X-ray photoelectron spectroscopy and Raman spectrum analysis confirmed that the defect structure at edge of CMK and oxygen-containing functional groups on surface of CMK were major active sites, contributing to the high catalytic activity. Free radical quenching analysis revealed that both SO4?? and ?OH were generated and participated in catalytic reaction. In addition, direct electron transfer by CMK to activate PDS also occurred, further promoting catalytic performance. Configuration of SDZ molecule was optimized using density functional theory, and the possible reaction sites in SDZ molecule were calculated using Fukui function. Combining ultra-high-performance liquid chromatography (UPLC)–mass spectrometry (MS)/MS analysis, three potential degradation pathways were proposed, including the direct removal of SO2 molecules, the 14S-17 N fracture, and the 19C-20 N and 19C-27 N cleavage of the SDZ molecule. The study demonstrated that ordered mesoporous carbon could work as a feasible catalytic material for PDS advanced oxidation during removal of antibiotics from wastewater.
- Cao, Di,Chen, Fan,Cheng, Hao,Huang, Cong,Li, Zhi-Ling,Liang, Bin,Nan, Jun,Sun, Kai,Wang, Ai-Jie
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supporting information
(2022/01/26)
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- Preparation method of succinic acid
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The invention discloses a preparation method of succinic acid. The preparation method comprises the following step: with malic acid as a raw material, carrying out one-step reaction in a hydrogen atmosphere in the presence or absence of a non-polar medium and under the action of a metal-solid acid bifunctional catalyst to obtain succinic acid. In the preparation method, the above raw materials can be derived from biomass resources, so dependence on petroleum resources is reduced. By controlling process conditions, succinic acid can be obtained with high yield. The preparation method is simple in process and mild in conditions.
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Paragraph 0028-0076
(2021/06/22)
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- Biosynthesis ofl-alanine fromcis-butenedioic anhydride catalyzed by a triple-enzyme cascadeviaa genetically modified strain
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In industry,l-alanine is biosynthesized using fermentation methods or catalyzed froml-aspartic acid by aspartate β-decarboxylase (ASD). In this study, a triple-enzyme system was developed to biosynthesizel-alanine fromcis-butenedioic anhydride, which was cost-efficient and could overcome the shortcomings of fermentation. Maleic acid formed bycis-butenedioic anhydride dissolving in water was transformed tol-alanineviafumaric acid andl-asparagic acid catalyzed by maleate isomerase (MaiA), aspartase (AspA) and ASD, respectively. The enzymatic properties of ASD from different origins were investigated and compared, as ASD was the key enzyme of the triple-enzyme cascade. Based on cofactor dependence and cooperation with the other two enzymes, a suitable ASD was chosen. Two of the three enzymes, MaiA and ASD, were recombinant enzymes cloned into a dual-promoter plasmid for overexpression; another enzyme, AspA, was the genomic enzyme of the host cell, in which AspA was enhanced by a T7promoter. Two fumarases in the host cell genome were deleted to improve the utilization of the intermediate fumaric acid. The conversion of whole-cell catalysis achieved 94.9% in 6 h, and the productivity given in our system was 28.2 g (L h)?1, which was higher than the productivity that had been reported. A catalysis-extraction circulation process for the synthesis ofl-alanine was established based on high-density fermentation, and the wastewater generated by this process was less than 34% of that by the fermentation process. Our results not only established a new green manufacturing process forl-alanine production fromcis-butenedioic anhydride but also provided a promising strategy that could consider both catalytic ability and cell growth burden for multi-enzyme cascade catalysis.
- Cui, Ruizhi,Liu, Zhongmei,Yu, Puyi,Zhou, Li,Zhou, Zhemin
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p. 7290 - 7298
(2021/09/28)
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- Preparation method of fumaric acid
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The invention discloses a preparation method of fumaric acid. The preparation method is characterized in that malic acid is used as a raw material, and under a solvent-free condition or in a hydrocarbon medium, malic acid is catalyzed to undergo a dehydration reaction so as to generate fumaric acid. The preparation method provided by the invention is simple in reaction process, and the key raw material malic acid can be obtained by fermenting biomass, so the preparation method is a supplement to a existing production route and relieve dependence on fossil resources; and besides, compared with a traditional fumaric acid production method, the method of the invention has the advantages that the use of high-pollution catalysts such as thiourea and oxybromide is avoided, and the method is green and safe since a dehydration reaction can be carried out under a normal-pressure condition. A catalyst used in the invention and a reaction process thereof are efficient and clean.
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Paragraph 0031-0095
(2021/06/22)
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- Fabrication of a stable Ti/Pb-TiOxNWs/PbO2 anode and its application in benzoquinone degradation
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To delay passivation of a titanium (Ti) substrate as well as enhance adhesion between an electrodeposited PbO2 coating and the Ti substrate, a titanium-lead composite oxide nanowire (Pb-TiOxNWs) intermediate layer was formed in situ on the surface of porous Ti by alkali etching, ion substitution, and high-temperature calcination. At the same time, Ti/PbO2 and Ti/TiO2NWs/PbO2 electrodes with porous Ti as a matrix were prepared for comparison. The surface structure and morphology of the prepared intermediate layer and the PbO2 coating were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The influences of the composite oxide intermediate layer on the electrochemical performance of the PbO2 electrode were analyzed by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and AC impedance spectroscopy (EIS). Accelerated lifetime tests were performed for electrodes with and without different intermediate layers. The results showed that PbOx was incorporated into the titanium dioxide three-dimensional network structure, resulting in formation of Pb-TiOxNWs. The surface of the Ti/Pb-TiOxNWs/PbO2 electrode was denser due to the smaller particle size of PbO2. The preferred crystal orientation of β(110) was observed for PbO2 deposited on Ti/Pb-TiOxNWs. The oxygen evolution potential reached a maximum of 2.19 V for Ti/Pb-TiOxNWs/PbO2. Accelerated life tests showed that compared with Ti/PbO2 and Ti/TiO2NWs/PbO2, the electrode life of Ti/Pb-TiOxNWs/PbO2 was increased by 91.7% and 35.3%, respectively. Therefore, it can be concluded that significantly improved morphology and electrochemical performance were achieved for titanium-based PbO2 electrodes by the addition of a Pb-TiOxNWs intermediate layer. In particular, the electrochemical stability of the PbO2 coating electrodes was improved markedly by the Pb-TiOxNWs intermediate layer. The electrodes were used for electrochemical oxidation of benzoquinone in wastewater (100 mg/L). It was found that chloride ions played a critical role in improving the current efficiency of electro-oxidative degradation. Under the same conditions, the COD removal rate in the presence of NaCl was 45% higher than in the presence of sulfate. The results of HPLC analysis of the intermediate products indicated that the oxidants electro-generated by chloride ions had stronger ring-opening and mineralization capabilities than those electro-generated by sulfate ions.
- Guo, Yingjuan,Tang, Changbin,Xue, Juanqin,Yu, Lihua,Zhang, Lihua
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- Selective C?O Bond Cleavage of Bio-Based Organic Acids over Palladium Promoted MoOx/TiO2
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Hydrodeoxygenation chemistries play a key role in the upgrading of biomass-derived feedstocks. Among these, the removal of targeted hydroxyl groups through selective C?O bond cleavage from molecules containing multiple functionalities over heterogeneous catalysts has shown to be a challenge. Herein, we report a highly selective and stable heterogeneous catalyst for hydrodeoxygenation of tartaric acid to succinic acid. The catalyst consists of reduced Mo5+ centers promoted by palladium, which facilitate selective C?O bond cleavage, while leaving intact carboxylic acid end groups. Stable catalytic performance over multiple cycles is demonstrated. This catalytic system opens up opportunities for selective processing of biomass-derived sugar acids with a high degree of chemical functionality.
- Albarracín-Suazo, Sandra,Nacy, Ayad,Nikolla, Eranda,Pagán-Torres, Yomaira J.,Roberts, Charles A.,Ruiz-Valentín, Génesis,de Lima e Freitas, Lucas Freitas
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p. 1294 - 1298
(2020/12/29)
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- Heterogeneous Fenton-like oxidative degradation of sulfanilamide catalyzed by RuO2-rectorite composite
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RuO2-rectorite (RuO2-Rec) was prepared by intercalation, deposition and calcination. Its structure was characterized by XRD, XPS, SEM and EDS. It was used as a catalyst for the sulfanilamide (SA) degradation in the presence of H2O2. Unlike sodium-rectorite and RuO2 which couldn’t catalyze the degradation of SA, RuO2-Rec could effectively catalyze the decomposition of H2O2 into hydroxyl radicals to degrade SA. The degradation rate could reach ~ 100% under the optimal conditions of 58?μmol/L of SA, 1.16?mmol/L of H2O2, 0.133?g/L of RuO2-Rec, pH 3.5 and 25?°C in 5?h. The degradation process conformed to pseudo-first-order kinetic correlation. This degradation was affected by pH, the amount of RuO2-Rec and the concentrations of H2O2 and SA. However, under the optimal pH value of 3.5, a high degradation rate could be achieved with the increase in SA concentration from 58?μmol/L to 290?μmol/L as long as the optimal ratio of RuO2-Rec, H2O2 and SA kept unchanged. In addition, RuO2-Rec was stable and possessed low ruthenium leaching rate and excellent reusability. Therefore, RuO2-Rec is expected to be an active catalyst for the pollutant removal in the heterogeneous Fenton-like system.
- Pan, Feifei,Yang, Jianhong,Cai, Jun,Liu, Lianye
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p. 4595 - 4611
(2021/07/26)
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- A plug-and-play chemobiocatalytic route for the one-pot controllable synthesis of biobased C4 chemicals from furfural
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Chemobiocatalytic selective transformation is an attractive yet challenging task, due to the incompatibility issues between different types of catalysts. In this work, one-pot, multi-step cascades integrating biocatalysis with organo-, base- and photocatalysis in a plug-and-play fashion were constructed for the controllable synthesis of eight C4 chemicals from furfural. Furfural was converted to 5-hydroxy-2(5H)-furanone (HFO) by sequential biocatalytic oxidation and photooxygenation in phosphate buffer, in >90% yields. Ring opening and concurrent isomerization of HFO to fumaric semialdehyde (FSA) were readily realized under mild conditions by a weakly basic resin (e.g., DVB resin). The versatile intermediate FSA could be oxidized to fumaric acid (FA) using a laccase-2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) system, which was further upgraded to amino acids including l-aspartic acid (l-Asp) and β-alanine (β-Ala) by whole-cell catalysis. Notably, amino acids were obtained from biobased furfural in a one-pot, four-step process with yields of up to 75%, without the isolation of any intermediates. Besides, the scale-up synthesis of l-Asp was demonstrated. This work demonstrates the great potential of the combination of chemo- and biocatalysis for selective furfural valorization.
- Huang, Yi-Min,Lu, Guang-Hui,Zong, Min-Hua,Cui, Wen-Jing,Li, Ning
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supporting information
p. 8604 - 8610
(2021/11/16)
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- Catalytic transfer hydrogenation of maleic acid with stoichiometric amounts of formic acid in aqueous phase: Paving the way for more sustainable succinic acid production
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The aqueous phase hydrogenation of maleic acid (MAc) to succinic acid (SAc) is demonstrated in the absence of any organic solvent and using stoichiometric amount of formic acid (FAc) as source of H2. Among the different noble metals (Pd, Au, Ru, Pt and Rh) and supports investigated (γ-Al2O3, TiO2, CeO2, ZrO2, WO3, CeZrO4, carbon, nicanite, SiO2 and TS-1), Pd/C was identified as the best catalyst. We observe that the undesirable formation of malic acid (MalAc) by hydration of MAc must be prevented. The transformation of MAc to SAc with negligible formation of MalAc is possible by using relatively mild temperature (140-150 °C) and a high catalyst to MAc ratio (i.e. fixed bed continuous flow reactor). Using the carboxylate forms (disodium maleate and sodium formate) instead of the acids results in an increase of the reaction rate. In a fixed bed reactor under a continuous flow of 15 wt% of MAc at a WHSV = 12 h-1 (contact time = 5 min), at 150 °C, 10 bar of N2 and using a formic acid/maleic acid molar ratio = 1, a yield of SAc close to 98% was obtained, equivalent to a productivity of 1.87 g SAc per gcat per·h. Leaching of Pd was below 0.02 ppm. No deactivation was observed in long term experiments at 150 °C (ca. 730 h), although the characterization of the used catalyst by CO chemisorption and TEM and XPS studies showed certain sintering of Pd particles. Regarding the mechanism of the reaction, kinetic isotopic experiments using deuterated DCOOH indicated that the reaction must essentially proceed via catalytic transfer hydrogenation, formyl H of formic acid is involved in the rate determining step of the reaction. When using maleate and formate sodium salts, the second H needed for the reaction is supplied by the solvent (H2O molecules). A preliminary environmental assessment (Life Cycle Analysis, LCA) of this CTH approach indicates that for relevant environmental categories of the LCA (such as climate change and consumption of fossil resources) the CTH process is greener than conventional hydrogenation process; the benefits are even larger if biomass-derived FAc is involved.
- López Granados,Moreno,Alba-Rubio,Iglesias,Martín Alonso,Mariscal
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supporting information
p. 1859 - 1872
(2020/04/07)
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- Study of the Oxidative Cleavage Proposed in the Biogenesis of Transtaganolides/Basiliolides: Pyran-2-one Aromaticity-Mediated Regioselective Control and Biogenetic Implications
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The synthetic feasibility of the oxidative cleavage: epoxidation of 7-O-geranylscopoletin followed by electrocyclic ring-opening, proposed in the biogenesis of transtaganolides/basiliolides is studied. Unlike the proposed pericyclic reactions, this pathway has not yet been addressed. Three synthetic strategies have been tested consisting of: i) Baeyer–Villiger oxidation of p-quinoids, ii) hydrolysis of quinone monoketals, or iii) direct fragmentation by using oxygen donors. Oxidation of the benzene ring of hydroxylated coumarins has been achieved using peroxyacids, but cleavage took place between undesired positions. The aromaticity conservation of the pyran-2-one cycle during oxidation is the controlling factor of these observed regioselectivities. The use of a 4,5-dihydroxy-2-methoxycinnamate model, in which the pyran-2-one ring does not exert influence on oxidation, has allowed the design of a synthetic sequence toward an analogue of the natural pyran-2-one isolated from Thapsia transtagana, key in the biogenesis. Mechanistic proposals for the obtained results as well as their biogenetic implications are raised.
- álvarez, José María,Jorge, Zacarías D.,Massanet, Guillermo M.
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supporting information
(2020/03/05)
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- N,N,O-Coordinated tricarbonylrhenium precatalysts for the aerobic deoxydehydration of diols and polyols
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Rhenium complexes are well known catalysts for the deoxydehydration (DODH) of vicinal diols (glycols). In this work, we report on the DODH of diols and biomass-derived polyols using L4Re(CO)3as precatalyst (L4Re(CO)3= tricarbonylrhenium 2,4-di-tert-butyl-6-(((2-(dimethylamino)ethyl)(methyl)amino)methyl)phenolate). The DODH reaction was optimized using 2 mol% of L4Re(CO)3as precatalyst and 3-octanol as both reductant and solvent under aerobic conditions, generating the active high-valent rhenium speciesin situ. Both diol and biomass-based polyol substrates could be applied in this system to form the corresponding olefins with moderate to high yield. Typical features of this aerobic DODH system include a low tendency for the isomerization of aliphatic external olefin products to internal olefins, a high butadiene selectivity in the DODH of erythritol, the preferential formation of 2-vinylfuran from sugar substrates, and an overall low precatalyst loading. Several of these features indicate the formation of an active species that is different from the species formed in DODH by rhenium-trioxo catalysts. Overall, the bench-top stable and synthetically easily accessible, low-valent NNO-rhenium complex L4Re(CO)3represents an interesting alternative to high-valent rhenium catalysts in DODH chemistry.
- Klein Gebbink, Robertus J. M.,Li, Jing,Lutz, Martin
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p. 3782 - 3788
(2020/06/22)
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- Directly Microwave-Accelerated Cleavage of C?C and C?O Bonds of Lignin by Copper Oxide and H2O2
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Model erythro, phenolic, and nonphenolic lignin β-O-4 dimer compounds are treated with copper oxide and H2O2 at the electronic field maximum position of a single-mode 2.45 GHz microwave system equipped with a cavity resonator. The products obtained through microwave heating and oil-bath heating with the same reaction vessel and temperature profile are quantitatively compared. Dimer degradation is found to proceed through consecutive elementary reactions. The phenolic dimer is dehydroxylated and this is followed by the spontaneous cleavage of Cα?Cβ and C?O?C bonds to produce guaiacol, vanillin, and vanillic acid. The reaction of the nonphenolic dimer produces veratric acid, veratraldehyde, and guaiacol. Microwave irradiation accelerates cleavage of the side chain and the oxidation of vanillin to vanillic acid. However, no acceleration of veratraldehyde oxidation to veratric acid or aromatic ring cleavage to produce dicarboxylic acids is observed. The selective acceleration of elementary reactions during the degradation of model lignin compounds indicates that microwaves interact with reaction intermediates that are sensitive to electromagnetic waves.
- Qu, Chen,Ito, Keigo,Katsuyama, Isamu,Mitani, Tomohiko,Kashimura, Keiichiro,Watanabe, Takashi
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p. 4510 - 4518
(2020/05/18)
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- A cobalt-substituted Keggin-Type polyoxometalate for catalysis of oxidative aromatic cracking reactions in water
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Efficient detoxification of harmful benzene rings into useful carboxylic acids in water is indispensable for achieving a clean water environment. We report herein that oxidative aromatic cracking (OAC) reactions in water were achieved using a catalytic system with a cobalt-substituted Keggin-Type polyoxometalate (Co-POM) as a catalyst, an Oxone monopersulfate compound as a sacrificial oxidant and sodium bicarbonate as an additive under mild conditions. Sodium bicarbonate plays a crucial role in the selective OAC reactions by Co-POM using ethylbenzenesulfonate as a model substrate. The reactive species was characterized to be a cobalt(iii)-oxyl species based on 31P NMR, UV-vis spectroscopic, kinetic, and theoretical analyses. The electrophilicity of the cobalt(iii)-oxyl species was demonstrated by a linear relationship with a negative slope in the Hammett plots of initial rates obtained from the OAC reactions of m-xylenesulfonate derivatives. Besides, we have verified the degradation pathway of the OAC reactions using benzene as a model substrate in the catalytic system. The degradation was initiated by an electrophilic attack of the cobalt(iii)-oxyl species on benzene to yield phenol followed by producing catechol, muconic acid, maleic/fumaric acid, tartaric acid derivatives and formic acid on the basis of 1H NMR spectroscopic analysis.
- Hong, Dachao,Kitagawa, Yasutaka,Kon, Yoshihiro,Shimoyama, Yoshihiro,Tamura, Satoru
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p. 8042 - 8048
(2020/12/28)
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- Deep eutectic solvent (DES) as both solvent and catalyst for oxidation of furfural to maleic acid and fumaric acid
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Efficient conversion of furfural to valuable chemicals is attracting attention because it is one of the bulk feedstocks in biomass refinery. Maleic acid (MA) and fumaric acid (FA) are two types of bulk monomers that can be prepared from furfural. Here, a simple method was developed to oxidize furfural to both MA and FA in a green deep eutectic solvent (DES). DES contained oxalic acid and choline chloride (ChCl); oxalic acid worked as both the main content of the solvent and acidic catalyst for the conversion. It was found that the conversion of furfural could reach 100%, while the yield of MA and FA reached 95.7% under a mild reaction temperature of 50 °C, which provided a green and efficient route for the synthesis of valuable monomers from furfural.
- Ni, Yong,Bi, Zhihao,Su, Hui,Yan, Lifeng
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p. 1075 - 1079
(2019/03/12)
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- Remarkable Reactivity of Boron-Substituted Furans in the Diels-Alder Reactions with Maleic Anhydride
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The reactivity of boron-substituted furans as dienes in the Diels-Alder reaction with maleic anhydride has been investigated. Gratifyingly, the furans with boryl substituents at C-3 gave the exo cycloadduct exclusively with excellent yields. In particular, the potassium trifluoroborate exhibited outstanding reactivity at room temperature. Theoretical calculations suggested that the trifluoroborate group is highly activating and also that the thermodynamics is the main factor that determines whether the products can be obtained efficiently or not.
- Medrán, Noelia S.,Dezotti, Federico,Pellegrinet, Silvina C.
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supporting information
p. 5068 - 5072
(2019/07/03)
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- Template free mild hydrothermal synthesis of core-shell Cu2O(Cu)?CuO visible light photocatalysts for N-acetyl-para-aminophenol degradation
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Solar photocatalytic processes are a promising approach to environmental remediation, however their implementation requires improvements in visible light harvesting and conversion and a focus on low cost, Earth abundant materials. Semiconducting copper oxides are promising visible light photocatalysts for solar fuels and wastewater depollution. Here we report the mild, hydrothermal (template-free) synthesis of core-shell Cu2O(Cu)?CuO photocatalytic architectures for the visible light photocatalytic degradation of N-acetyl-para-aminophenol (APAP). Hollow and rattle-like core-shell nanosphere aggregates with diameters between 200 nm and 2.5 μm formed under different synthesis conditions; all comprised an inner Cu2O shell, formed of 10-50 nm nanoparticles, surrounded by a protective corona of CuO nanoparticles. High reductant and structure-directing agent concentrations promoted the formation of a yolk-like Cu2O/Cu core, associated with improved photophysical properties, notably a high oxidation potential and suppressed charge carrier recombination, that correlated with the highest apparent quantum efficiency (8%) and rate of APAP removal (7 μmol g-1 min-1). Trapping experiments demonstrated hydroxyl radicals were the primary active species responsible for APAP oxidation to quinones and short chain carboxylic acids. Rattle-like core-shell Cu2O/Cu?CuO nanospheres exhibited excellent physiochemical stability and recyclability for APAP photocatalytic degradation.
- Karthikeyan, Sekar,Chuaicham, Chitiphon,Pawar, Radheshyam R.,Sasaki, Keiko,Li, Wei,Lee, Adam F.,Wilson, Karen
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supporting information
p. 20767 - 20777
(2019/09/30)
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- Double-carbonylation preparation method utilizing palladium to catalyze acetylene
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The invention provides a double-carbonylation preparation method utilizing palladium to catalyze acetylene and relates to the field of preparing succinic acid by an acetylene method. According to thedouble-carbonylation preparation method, acetylene, carbon monoxide and water are utilized as raw materials to be catalyzed and synthesized into succinic acid (anhydride) under the conditions of a reaction temperature as 25 to 75 DEG C and a pressure as 0.1 to 5MPa. To the used catalyst, a palladium compound-lithium halide/hydrogen halide-nitrogenous/phosphine ligand is utilized as the catalyst, wherein n (palladium compound) to n (lithium halide/hydrogen hydride) is equal to 1 to (1 to 10), and n (phosphine/nitrogen ligand) to n (palladium compound) is equal to 1 to (1 to 10). Compared with the prior art, the double-carbonylation preparation method disclosed by the invention has the advantages of moderate reaction conditions, quick reaction speed, high selectivity, simpleness and safety in operation, ability in effectively reducing succinic acid production cost and very good industrial market prospect.
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Paragraph 0026; 0028; 0030; 0032; 0034; 0036
(2018/04/03)
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- METHOD FOR MANUFACTURING ORGANIC ACID
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The present invention provides a method for manufacturing organic acids. The method for manufacturing organic acids may comprise a step of forming organic acids by conducting degradation of alginate in water using a catalyst. Otherwise, the method for manufacturing organic acids may comprise the steps of: forming a mixture by mixing water, a catalyst, and alginate; heating the mixture; forming a product containing an organic acid by conducting the degradation of alginate by the catalyst in the heated mixture; and cooling the product. According to embodiments of the present invention, a high-value organic acid can be manufactured by degrading the alginate. In addition, yields by kinds of organic acids can be controlled by varying reaction conditions, so the yield of the desired organic acid can be selectively increased.
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Paragraph 0036-0044
(2018/09/12)
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- Rearrangements and Tautomeric Transformations of Heterocyclic Compounds in Homogeneous Reaction Systems Furfural–Н2О2–Solvent
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General information on the reactions of furfurals with hydrogen peroxide is given. We have discussed the Baeyer–Villiger rearrangement of furan 2-hydroxyhydroperoxides and tautomeric transformations with proton transfer of 2-hydroxyfuran and β-formylacrylic acid formed in a homogeneous reaction system furfural–Н2О2–solvent under the catalysis with the formed acids. The factors affecting these rearrangements and tautomeric transformations as well as their specificity in comparison with benzene type compounds, and the pathway of the reactions of furan aldehydes with Н2О2 in water have been analyzed. Ketoenol tautomerism of cyclic hemiacetal form of β-formylacrylic acid leading to its transformation into succinic anhydride has been described for the first time.
- Badovskaya,Poskonin
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p. 1568 - 1579
(2018/11/10)
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- Adipic acid production via metal-free selective hydrogenolysis of biomass-derived tetrahydrofuran-2,5-dicarboxylic acid
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Biomass-derived furans offer sustainable routes to adipic acid (AA), a key chemical in Nylon-6,6 synthesis. In this work, we show that tetrahydrofuran-2,5-dicarboxylic acid (THFDCA) is a viable precursor for AA production, achieving up to 89% yield in a metal-free system containing HI and molecular H2 in a propionic acid solvent at 160 °C. Reactivity studies demonstrate that the interplay between HI, H2, and the solvent is essential for effective THFDCA ring opening. By measuring the reaction orders of HI and molecular H2 and calculating an acid?base equilibrium constant in a nonaqueous solvent, we show that HI plays a multifaceted role in the reaction by acting both as a proton source and an iodide source to selectively cleave C?O bonds without overhydrogenation of carboxylic acid groups. Using reactivity studies, kinetic measurements, and first-principles computational insights, we demonstrate that metal-free activation of molecular H2 plays a key role in the reaction, following HI-mediated cleavage of the etheric C?O bond in THFDCA.
- Gilkey, Matthew J.,Mironenko, Alexander V.,Vlachos, Dionisios G.,Xu
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p. 6619 - 6634
(2017/11/09)
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- PROCESS FOR THE PREPARATION OF PHARMACEUTICAL GRADE DIMETHYL FUMARATE
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The present invention relates to a process for the preparation of dimethyl fumarate of formula (1) from fumaric acid of formula (3). The present process is simple, cost effective and feasible in large scale production. Dimethyl fumarate obtained by the present process is free of geno toxic impurities.
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Page/Page column 7
(2017/02/09)
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- Synthesis of maleic and fumaric acids from furfural in the presence of betaine hydrochloride and hydrogen peroxide
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Here we report the successful valorisation of furfural into maleic acid (MA) and fumaric acid (FA) with a total yield above 90% using an aqueous solution of betaine hydrochloride (BHC) in the presence of hydrogen peroxide. BHC can be recycled for at least 4 cycles and it can be used to directly convert xylose to MA and FA.
- Araji,Madjinza,Chatel,Moores,Jér?me,De Oliveira Vigier
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- N-Doped graphene as a metal-free catalyst for glucose oxidation to succinic acid
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N-Containing graphenes obtained either by simultaneous amination and reduction of graphene oxide or by pyrolysis of chitosan under an inert atmosphere have been found to act as catalysts for the selective wet oxidation of glucose to succinic acid. Selectivity values over 60% at complete glucose conversion have been achieved by performing the reaction at 160 °C and 18 atm O2 pressure for 20 h. This activity has been attributed to graphenic-type N atoms on graphene. The active N-containing graphene catalysts were used four times without observing a decrease in conversion and selectivity of the process. A mechanism having tartaric and fumaric acids as key intermediates is proposed.
- Rizescu, Cristina,Podolean, Iunia,Albero, Josep,Parvulescu, Vasile I.,Coman, Simona M.,Bucur, Cristina,Puche, Marta,Garcia, Hermenegildo
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p. 1999 - 2005
(2017/06/09)
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- Preparation method of a kind of fumaric acid
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The invention provides a preparation method for fumaric acid, and relates to the production technical field of fumaric acid. The preparation method comprises: adding maleic anhydride into a reaction medium, without any catalyst or adding sulfuric acid and phosphoric acid as catalysts, in an N2 sealed environment, heating to 140 DEG C-220 DEG C and stirring for a reaction, after the reaction is finished, stirring for cooling and crystallization until the temperature is 40 DEG C or less, centrifuging the crystallization liquid to obtain fumaric acid crystal, drying to obtain high-purity fumaric acid. The yield of fumaric acid by employing the preparation method reaches up to 99.5% or more, the mother liquor after the fumaric acid crystal liquid is centrifuged can be subsequently cycled as the reaction work medium, so that no any wastewater or exhaust gas is generated, and the green production of fumaric acid is realized. Fumaric acid prepared by employing the preparation method is accord with national standard of 'GB25546-2010 foodstuff additive fumaric acid' and 'NY-T920-2004 feed grade fumaric acid'.
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Paragraph 0034; 0035
(2017/01/23)
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- PROCESS FOR PREPARATION OF DIMETHYL FUMARATE
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The present invention relates to a process for the preparation of dimethyl fumarate, a compound of formula I, in a purity of at least 99.0% as determined by HPLC, containing less than 400 ppm of an anion of a mineral acid and less than 5 ppm of dimethyl maleate.
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Paragraph 0148
(2016/09/12)
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- Degradation of 2,4-dichlorophenol from aqueous using UV activated persulfate: Kinetic and toxicity investigation
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2,4-DCP is a high-toxicity phenol compound, which is difficult to remove, harmful to the health of people and seriously influences the aquatic ecosystems. In this study, the degradation of 2,4-DCP using UV/persulfate (UV/PS) process was investigated for the first time. The results showed pseudo-first-order rate constants of 2,4-DCP photo-degradation by UV/PS was 35.1 × 10-3 min-1. The reaction rate constants increased with pH increasing from 5 to 7 and then decreased at pH 8. Different anions (Cl-, HCO3- and NO3-) in water presented different effects on the photo-degradation reaction. The photo-degradation rates of 2,4-DCP in three actual water conditions (Xidong water works, Xijiu reservoir, Henshan reservoir) were higher than in the ultrapure water. Two possible (hydroxylated and dechlorinated) pathways for the degradation of 2,4-DCP by UV/PS were proposed. The luminescent bacteria inhibition rate greatly decreased with the concentration of 2,4-DCP decreasing in the reaction process.
- Chen, Juxiang,Gao, Naiyun,Lu, Xian,Xia, Meng,Gu, Zhenchuan,Jiang, Chuang,Wang, Qiongfang
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p. 100056 - 100062
(2016/11/09)
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- Application of anodic oxidation, electro-Fenton and UVA photoelectro-Fenton to decolorize and mineralize acidic solutions of Reactive Yellow 160 azo dye
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The degradation of 100 cm3 of a solution with 0.167 mmol dm-3 Reactive Yellow 160 (RY160) azo dye in sulfate medium at pH 3.0 has been comparatively studied by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF). Trials were carried out with a stirred tank reactor equipped with a boron-doped diamond (BDD) anode and an air-diffusion cathode for H2O2 production, upon addition of 0.50 mmol dm-3 Fe2+ as catalyst in EF and PEF. The solution was slowly decolorized by AO-H2O2 because of the low rate of reaction of the azo dye and its colored products with hydroxyl radicals generated at the BDD anode from water oxidation. The color loss was enhanced in EF by the larger oxidation ability of hydroxyl radicals produced in the bulk from Fenton's reaction between added Fe2+ and generated H2O2, whereas the solution was more rapidly decolorized by PEF owing to the additional generation of hydroxyl radicals from the photolysis of Fe(III)-hydroxy complexes by UVA light. The relative mineralization ability of the processes also increased in the sequence AO-H2O2 -2. The influence of current density and RY160 concentration on the performance of all processes was assessed. Final carboxylic acids like maleic, fumaric, tartronic, acetic, oxalic, oxamic and formic were quantified by ion-exclusion HPLC. All these acids were totally removed by PEF, but the formation of small amounts of other highly recalcitrant products impeded the total mineralization. Chloride, sulfate, ammonium and, to a smaller extent, nitrate ions were released to the solution from the heteroatoms of the azo dye in all cases.
- Bedolla-Guzman, Alejandro,Sirés, Ignasi,Thiam, Abdoulaye,Peralta-Hernández, Juan Manuel,Gutiérrez-Granados, Silvia,Brillas, Enric
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p. 307 - 316
(2016/05/11)
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- Linker Installation: Engineering Pore Environment with Precisely Placed Functionalities in Zirconium MOFs
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Precise placement of multiple functional groups in a highly ordered metal-organic framework (MOF) platform allows the tailoring of the pore environment, which is required for advanced applications. To realize this, we present a comprehensive study on the linker installation method, in which a stable MOF with coordinatively unsaturated Zr6 clusters was employed and linkers bearing different functional groups were postsynthetically installed. A Zr-MOF with inherent missing linker sites, namely, PCN-700, was initially constructed under kinetic control. Twelve linkers with different substituents were then designed to study their effect on MOF formation kinetics and therefore resulting MOF structures. Guided by the geometrical analysis, linkers with different lengths were installed into a parent PCN-700, giving rise to 11 new MOFs and each bearing up to three different functional groups in predefined positions. Systematic variation of the pore volume and decoration of pore environment were realized by linker installation, which resulted in synergistic effects including an enhancement of H2 adsorption capacities of up to 57%. In addition, a size-selective catalytic system for aerobic alcohol oxidation reaction is built in PCN-700 through linker installation, which shows high activity and tunable size selectivity. Altogether, these results exemplify the capability of the linker installation method in the pore environment engineering of stable MOFs with multiple functional groups, giving an unparalleled level of control.
- Yuan, Shuai,Chen, Ying-Pin,Qin, Jun-Sheng,Lu, Weigang,Zou, Lanfang,Zhang, Qiang,Wang, Xuan,Sun, Xing,Zhou, Hong-Cai
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supporting information
p. 8912 - 8919
(2016/07/30)
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- Efficient removal of Orange G using Prussian Blue nanoparticles supported over alumina
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Prussian Blue nanoparticles (PBNP) synthetized and adsorbed onto γ-Al2O3 spheres were prepared and characterized by transition and scanning electron microscopy (TEM, SEM), energy dispersive X-ray spectroscopy (EDS) and sorptometry. Adsorption and reaction runs were performed using aqueous solutions of a model azo dye Orange G. The adsorption capacity of the PBNP/γ-Al2O3 at 323 and 343 K at initial pH 3 and 6 was studied. The presence of PBNP increased the adsorption capacity of the support and this effect was more pronounced at initial pH 6. However, since the adsorbent life time was narrow and its regeneration quite difficult, PBNP/γ-Al2O3 was tested as a heterogeneous Fenton-like catalyst. The catalytic activity and stability for oxidation of Orange G were investigated in terms of discolouration, TOC and oxidant conversion. At the best operating condition studied (343 K and pH0 = 3), complete dye discolouration and 60% of mineralization were attained while reaction largely overcomes adsorption. At this temperature the catalyst activity and its characteristics remained almost invariable during 9 cycles of 5 h each and iron leaching occurred in low extent.
- Doumic,Salierno,Cassanello,Haure,Ayude
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- Facile preparation of a Ti/α-PbO2/β-PbO2 electrode for the electrochemical degradation of 2-chlorophenol
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A Ti/α-PbO2/β-PbO2 electrode with high stability was prepared and examined toward the electrochemical degradation of 2-chlorophenol. Scanning electron microscopy analysis revealed that Ti/α-PbO2/β-PbO2 had a cauliflower morphology comprising small β-PbO2 crystals. The 2-chlorophenol removal rate using the Ti/α-PbO2/β-PbO2 electrode was 100% after 180 min of electrolysis under optimal conditions, which were selected based on the orthogonal test method, i.e., initial concentration of 2-cholorophenol = 50 mg/L, concentration of Na2SO4 = 0.1 mol/L, temperature = 35°C, and anode current density = 20 mA/cm2. Kinetic analyses demonstrated that the electrochemical oxidation of 2-chlorophenol on the Ti/α-PbO2/β-PbO2 electrode followed pseudo-first order kinetics.
- Zhang, Qianli,Guo, Xinyan,Cao, Xiaodan,Wang, Dongtian,Wei, Jie
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p. 975 - 981
(2015/07/01)
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- A novel example of double reactivity by either photochemical [2+2] or thermal additions of an ionic organic supramolecular assembly
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An example of double reactivity in the solid state was achieved from a single binary array directed by charge-assisted hydrogen bonds assembled via mechanochemistry: [(HFu-)(Im+)] (1). The photochemical transformation of 1 occurs via a topotactic fashion with a quantitative yield followed by a second grinding-irradiation cycle. The recrystallisation of the photoproduct produces a novel hydrogen supramolecular isomer of [(rctt-H2Cbtc2-)(Im+)2] (2). Another example of the regioselective and quantitative preparation of rtct-cyclobutane isomers was obtained from the controlled isomerisation of 2 under hydrothermal conditions. Upon heating, 1 produced an unexpected hydroamination product (3) in almost quantitative yield. The stereochemistry of products 2 and 3 was confirmed by X-ray single crystal diffraction analysis.
- Brice?o, Alexander,Leal, Dayana,Díaz De Delgado, Graciela
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p. 4965 - 4971
(2015/06/16)
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- Liquid hydrogenation of maleic anhydride with Pd/C catalyst at low pressure and temperature in batch reactor
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Succinic acid (SA) produced from hydrogenation of maleic anhydride (MAN) is used widely in manufacturing of pharmaceuticals, agrochemicals, surfactants and detergent, green solvent and biodegradable plastic. In this study, we performed that liquid hydrogenation of MAN to SA with 5 wt% Pd supported on activated carbon (Pd/C) at low pressure and temperature. The synthesis of SA was performed in aqueous solution while varying temperature, pressure, catalytic amount and agitation speed. We confirmed that the composition of the products consisting of SA, maleic acid (MA), fumaric acid (FA) and malic acid (MLA) depends on the process. The catalytic characteristics were analyzed by TGA, TEM.
- Kim, Ji Sun,Baek, Jae Ho,Ryu, Young Bok,Hong, Seong-Soo,Lee, Man Sig
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p. 290 - 294
(2015/03/05)
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- Catalytic hydrothermal conversion of macroalgae-derived alginate: Effect of pH on production of furfural and valuable organic acids under subcritical water conditions
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The hydrothermal decomposition of sodium alginate was analyzed in subcritical water as a function of pH in order to investigate the effects of catalysts on the production of value-added chemicals. A base-catalysed reaction at pH 13 promoted the decomposition of alginate, resulting in the production of lactic acid, fumaric acid and malic acid as major species. At pH 1, monomers (mannuronic acid and guluronic acid), furfural and glycolic acid were predominantly produced by the acid-catalysed hydrothermal decomposition of alginate. Increasing the reaction temperature enhanced both the acid- and base-catalysed reactions, albeit by varying degrees dependent upon the catalyst type. Our results demonstrate that optimizing the reaction temperature and pH is critical for the efficient conversion of seaweed-derived biomass into valuable products.
- Jeon, Wonjin,Ban, Chunghyeon,Park, Geonu,Yu, Tae-Kyung,Suh, Jeong-Yong,Woo, Hee Chul,Kim, Do Heui
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p. 106 - 113
(2015/03/05)
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- Acrylates via Metathesis of Crotonates
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Crotonic acid has the potential to be produced from renewable resources at low cost but currently has a limited market. We are investigating catalytic routes to exploit the functionalities of crotonic acid to produce a range of established industrial chemicals. Here we report our work on converting crotonates to acrylates, where a cost-competitive bio-based alternative can provide a market advantage. Our optimized reaction conditions for the cross-metathesis between crotonates and ethylene resulted in an increase in catalyst turnover numbers by 2 orders of magnitude compared with literature values. Control experiments showed the cross-metathesis with ethylene to be an equilibrium reaction. The turnover-number-limiting factor was found to be the stability of the metathesis catalyst.
- Schweitzer, Dirk,Snell, Kristi D.
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supporting information
p. 715 - 720
(2015/07/27)
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- Upgrading malic acid to bio-based benzoates via a Diels-Alder-initiated sequence with the methyl coumalate platform
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The conversion of naturally-occurring malic acid to the 2-pyrone methyl coumalate was optimized using a variety of acid catalysts. Coupling methyl coumalate with electron-rich dienophiles in an inverse electron-demand Diels-Alder (IEDDA)/decarboxylation/elimination domino sequence resulted in an investigation of the scope and limitations of the methodology. The thermal, metal-free, and one-pot procedure allows regioselective access to diverse aromatic compounds including tricyclic, biphenyl, and pyridinyl systems for elaboration. A comparison with analogous pyrones demonstrates the striking efficacy of methyl coumalate as a versatile platform for the generation of biorenewable functionalized benzoates. This journal is
- Lee, Jennifer J.,Pollock Iii, Gerald R.,Mitchell, Donald,Kasuga, Lindsay,Kraus, George A.
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p. 45657 - 45664
(2015/02/19)
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- Renewable production of phthalic anhydride from biomass-derived furan and maleic anhydride
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A route to renewable phthalic anhydride (2-benzofuran-1,3-dione) from biomass-derived furan and maleic anhydride (furan-2,5-dione) is investigated. Furan and maleic anhydride were converted to phthalic anhydride in two reaction steps: Diels-Alder cycloaddition followed by dehydration. Excellent yields for the Diels-Alder reaction between furan and maleic-anhydride were obtained at room temperature and solvent-free conditions (SFC) yielding 96% exo-4,10-dioxa-tricyclo[5.2.1.0]dec-8-ene-3,5-dione (oxanorbornene dicarboxylic anhydride) after 4 h of reaction. It is shown that this reaction is resistant to thermal runaway because of its reversibility and exothermicity. The dehydration of the oxanorbornene was investigated using mixed-sulfonic carboxylic anhydrides in methanesulfonic acid (MSA). An 80% selectivity to phthalic anhydride (87% selectivity to phthalic anhydride and phthalic acid) was obtained after running the reaction for 2 h at 298 K to form a stable intermediate followed by 4 h at 353 K to drive the reaction to completion. The structure of the intermediate was determined. This result is much better than the 11% selectivity obtained in neat MSA using similar reaction conditions.
- Mahmoud, Eyas,Watson, Donald A.,Lobo, Raul F.
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p. 167 - 175
(2014/01/06)
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- Degradation of chlorinated phenols in water in the presence of H 2O2 and water-soluble μ-nitrido diiron phthalocyanine
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Efficient disposal of pollutants is a key problem in the environmental context. In particular, chlorinated aromatic compounds are recalcitrant to biodegradation and conventional treatment methods. Iron phthalocyanines were previously shown to be efficient catalysts for the oxidative degradation of chlorinated phenols considered as priority pollutants. We have recently discovered μ-nitrido diiron phthalocyanines as powerful oxidation catalysts. Herein, we evaluate these emerging catalysts in the oxidation of chlorinated phenols in comparison with conventional mononuclear complex. Catalytic performance of iron tetrasulfophthalocyanine (FePcS) and corresponding μ-nitrido dimer [(FePcS)2N] have been compared in the oxidation of chlorinated phenols by hydrogen peroxide in water. The oxidative degradation of 2,6-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) has been studied. The (FePcS)2N exhibited better catalytic properties than mononuclear FePcS in terms of conversion and mineralization (transformation of organic chlorine to Cl- and decrease of total organic carbon due to the formation of CO2). Kinetics of the DCP oxidation indicated that different reaction mechanisms are involved in the presence of FePcS and (FePcS)2N. The high catalytic activity of (FePcS)2N in the degradation and mineralization of chlorinated phenols make μ-nitrido diiron phthalocyanines promising catalyst to apply also in environmental remediation.
- Colomban, Cédric,Kudrik, Evgeny V.,Afanasiev, Pavel,Sorokin, Alexander B.
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- Synthesis of Pd nanoparticles decorated with graphene and their application in electrocatalytic degradation of 4-chlorophenol
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Pd/graphene catalysts were prepared in situ from graphite oxide and palladium salts by the hydrogen-reduction method and were then used for the construction of Pd/graphene gas-diffusion electrodes (GDE). The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential pulse voltammetry (DPV) techniques. In the Pd/graphene catalysts, Pd particles, with an average size of 3.6 nm and an amorphous structure, were highly dispersed in the graphene. The Pd/graphene catalysts accelerated the two-electron reduction of O2to H2O2by feeding air, which favors the production of hydroxyl radicals (HO?). In the electrolytic system, HO? was determined in the reaction mixture by the electron spin resonance spectrum (ESR). The dechlorination degree of 4-chlorophenol reached approximately 90.5% after 80 min, and the removal efficiency and the average removal efficiency of 4-chlorophenol. in terms of total organic carbon (TOC) after 120 min, reached approximately 93.3% and 85.1%, respectively. Furthermore, based on the analysis of electrolysis intermediates by high performance liquid chromatography (HPLC) and ion chromatography (IC), a reaction scheme was proposed for the Pd/grapheme GDE catalytic degradation of 4-chlorophenol.
- Bian, Zhao-Yong,Bian, Yu,Wang, Hui,Ding, Ai-Zhong
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p. 7279 - 7285
(2015/01/09)
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- Degradation of a veterinary pharmaceutical product in water by electro-oxidation using a BDD anode
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The electrochemical oxidation (EO) treatment in water of Fantetra, a veterinary drug widely used in Chile, and its components: oxytetracycline hydrochloride, phtalylsulfathiazole and diphenhydramine, has been carried out at constant current using a BDD/Stainless steel system. First, solutions of each drug were electrolyzed following the decay of the absorbance of each compound and total organic carbon abatement. The mineralization of the Fantetra commercial formulation was also studied. An analysis of the degradation by-products was made by high performance liquid chromatography. Thus, during the degradation of each pharmaceutical by the electrochemical oxidation process, aliphatic carboxylic acids were detected prior to their complete mineralization to CO2 and nitrogen ions, while NO3- and NH4+ remain in the treated solution. This is an essential preliminary step towards the applicability of the EO processes for the treatment of wastewater containing pharmaceutical compounds.
- Espinoza, C.,Contreras, N.,Berros, C.,Salazar, R.
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p. 2507 - 2511
(2015/02/05)
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- Poly-(styrene sulphonic acid): An acid catalyst from polystyrene waste for reactions of interest in biomass valorization
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This article reports on the use of poly-(styrene sulphonic acid) (PSSA) prepared by sulphonation of polystryrene waste as catalyst in reactions demanding acid sites. Two different waste derived catalysts (waste to catalyst, WTC) were studied: soluble PSSA (WTC-PSSA) and solid SiO2-PSSA nanocomposite (WTC-SiO2-PSSA). The catalytic properties of these waste derived acid catalysts have been explored in three different reactions of interest in biomass valorization: biodiesel synthesis, xylose dehydration to furfural and furfural oxidation to maleic and succinic acids. The results show that both soluble and nanocomposite WTC catalysts present promising catalytic properties. The WTC-PSSA requires ultrafiltration for reutilization whereas the WTC-SiO2-PSSA can be separated from the reaction mixtures by more usual techniques (centrifugation or conventional filtration). Further research is required for improving the hydrothermal stability of WTC-SiO2-PSSA in order to substantially reduce the leaching of polymer that takes place during the catalytic runs.
- Alonso-Fagúndez,Laserna,Alba-Rubio,Mengibar,Heras,Mariscal,Granados, M. López
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p. 285 - 294
(2014/07/07)
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- Effect of acid-base properties of the medium on the reactions in the 2-furaldehyde-H2O2-H2O system with and without VOSO4
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Data on the effect of acid-base properties of the medium in the pH range 0-9 on the intensity of transformation of 2-furaldehyde and the direction of the multi-stage reactions in the 2-furaldehyde-H2O2-H 2O system in the presence of VOSO4 and without it are presented. Significant influence of the medium pH value on the reaction pathway in the system under investigation hase been found. Mechanism of these reactions considering the effect of acid-base properties of the medium has been suggested.
- Badovskaya,Poskonin,Ponomarenko
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p. 1133 - 1140
(2014/08/05)
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- Self-assembly, concomitant photochemical processes, and improvement of the yield of [2 + 2] photoreactions from supramolecular arrays via mechanochemical assistance
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Novel examples of self-assembly, structural transformations and concomitant photochemical processes from supramolecular ternary assemblies directed by charge-assisted hydrogen bonds are shown. In addition, mechanochemical assistance is also shown as a potential tool in order to improve the yield of [2 + 2] photoreactions in the solid state.
- Briceno, Alexander,Leal, Dayana,Ortega, Gabriela,De Delgado, Graciela Diaz,Ocando, Edgar,Cubillan, Liz
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p. 2795 - 2799
(2013/07/05)
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