- Synthesis of an Acylphosphate Driven by a Proton Gradient. A Model for H(+)-ATPase
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We describe the first model for a proton pump, H(+)-ATPase.This model uses the energy from an indirect transfer of two protons from a solution at pH 0.3 to a solution at pH 10 to drive the synthesis of a high-energy phosphate, citraconyl phosphate.
- Colton, Ian J.,Kazlauskas, Romas J.
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- Synthesis and pH-dependent hydrolysis profiles of mono- and dialkyl substituted maleamic acids
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Maleamic acid derivatives as weakly acid-sensitive linkers or caging groups have been used widely in smart delivery systems. Here we report on the controlled synthetic methods to mono- and dialkyl substituted maleamic acids and their pH-dependent hydrolysis behaviors. Firstly, we studied the reaction between n-butylamine and citraconic anhydride, and found that the ratio of the two n-butyl citraconamic acid isomers (α and β) could be finely tuned by controlling the reaction temperature and time. Secondly, we investigated the effects of solvent, basic catalyst, and temperature on the reaction of n-butylamine with 2,3-dimethylmaleic anhydride, and optimized the reaction conditions to efficiently synthesize the dimethylmaleamic acids. Finally, we compared the pH-dependent hydrolysis profiles of four OEG-NH2 derived water-soluble maleamic acid derivatives. The results reveal that the number, structure, and position of the substituents on the cis-double bond exhibit a significant effect on the pH-related hydrolysis kinetics and selectivity of the maleamic acid derivatives. Interestingly, for the mono-substituted citraconamic acids (α-/β-isomer), we found that their hydrolyses are accompanied by the isomerization between the two isomers.
- Su, Shan,Du, Fu-Sheng,Li, Zi-Chen
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- Synthesis of bio-based methacrylic acid from biomass-derived itaconic acid over barium hexa-aluminate catalyst by selective decarboxylation reaction
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An environmentally-benign, efficient and inexpensive high-surface-area barium hexa-aluminate (BaAl12O19, BHA) was developed as a catalyst for the decarboxylation of the biomass-derived itaconic acid (IA) to bio-based methacrylic acid (MAA). A maximal 50% final yield of MAA with a high product selectivity was obtained under relatively mild synthesis reaction conditions (250 °C; 20 bar N2). The reported selective MAA production was elevated, operating process characteristics were significantly less harsh, and no depleting critical raw materials were utilized when paralleled to the procedures with alkaline mineral bases, noble metal-containing heterogeneous catalysis systems and unrenewable feed resources (e.g. isobutene), applied previously. It was found that the doping of palladium on BHA support (Pd@BHA) did not improve MAA productivity. The effect of the time (25–300 min), temperature (175–275 °C), pressure (10–40 bar), reacting substrate concentration (0.10–0.19 mol L–1), metallic oxide mass (0.5–3.0 g) and type on IA conversion, MAA content MAA content and rates was determined, examining also recyclability. BHA catalyst was characterized with various structural techniques, such as energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), CO2 temperature-programmed desorption (TPD), scanning electron microscopy (SEM) and N2 physisorption.
- Bohre, Ashish,Novak, Uro?,Grilc, Miha,Likozar, Bla?
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- BIO-BASED METHACRYLIC ACID AND OTHER ALKENOIC-DERIVED MONOMERS VIA CATALYTIC DECARBOXYLATION
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A novel method for the catalytic selective decarboxylation of a starting material to produce an organic acid is disclosed. According to at least one embodiment, the method may include placing a reaction mixture into a reaction vessel, the reaction mixture including a solvent, a starting material, and a catalyst, subjecting the reaction mixture to a predetermined pressure and temperature, and allowing the reaction to continue for 1-3 hours. The starting material may be at least one of a dicarboxylic acid, a tricarboxylic acid, and an anhydride of a dicarboxylic or tricarboxylic acid. As an exemplary embodiment, itaconic acid may be a starting material and the organic acid may be methacrylic acid. The predetermined temperature may be 250° C. or less, and the reaction pressure may be less than 425 psi. Further, a polymerization inhibitor may be used.
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Paragraph 0060-0061
(2018/04/26)
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- Methacrylic acid production method
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A method of producing methacrylic acid using a hydrotalcite catalyst and subcritical water is described.
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Page/Page column 9; 14-15
(2018/12/11)
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- Synthesis of Bio-Based Methacrylic Acid by Decarboxylation of Itaconic Acid and Citric Acid Catalyzed by Solid Transition-Metal Catalysts
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Methacrylic acid, an important monomer for the plastics industry, was obtained in high selectivity (up to 84 %) by the decarboxylation of itaconic acid using heterogeneous catalysts based on Pd, Pt and Ru. The reaction takes place in water at 200–250 °C without any external added pressure, conditions significantly milder than those described previously for the same conversion with better yield and selectivity. A comprehensive study of the reaction parameters has been performed, and the isolation of methacrylic acid was achieved in 50 % yield. The decarboxylation procedure is also applicable to citric acid, a more widely available bio-based feedstock, and leads to the production of methacrylic acid in one pot in 41 % selectivity. Aconitic acid, the intermediate compound in the pathway from citric acid to itaconic acid was also used successfully as a substrate.
- Le N?tre, Jér?me,Witte-van Dijk, Susan C. M.,van Haveren, Jacco,Scott, Elinor L.,Sanders, Johan P. M.
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p. 2712 - 2720
(2016/12/23)
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- A biocompatible alkene hydrogenation merges organic synthesis with microbial metabolism
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Organic chemists and metabolic engineers use orthogonal technologies to construct essential small molecules such as pharmaceuticals and commodity chemicals. While chemists have leveraged the unique capabilities of biological catalysts for small-molecule production, metabolic engineers have not likewise integrated reactions from organic synthesis with the metabolism of living organisms. Reported herein is a method for alkene hydrogenation which utilizes a palladium catalyst and hydrogen gas generated directly by a living microorganism. This biocompatible transformation, which requires both catalyst and microbe, and can be used on a preparative scale, represents a new strategy for chemical synthesis that combines organic chemistry and metabolic engineering. Reduction to practice: A hydrogenation reaction has been developed that employs hydrogen generated in situ by a microorganism and a biocompatible palladium catalyst to reduce alkenes on a synthetically useful scale. This type of transformation, which directly combines tools from organic chemistry with the metabolism of a living organism for small-molecule production, represents a new strategy for chemical synthesis.
- Sirasani, Gopal,Tong, Liuchuan,Balskus, Emily P.
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supporting information
p. 7785 - 7788
(2014/08/05)
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- A PROCESS FOR THE PRODUCTION OF METHACRYLIC ACID AND ITS DERIVATIVES AND POLYMERS PRODUCED THEREFROM
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A process for the production of methacrylic acid by the base catalysed decarboxylation of at least one dicarboxylic acid selected from itaconic, citraconic or mesaconic acid or mixtures thereof is described. The decarboxylation is carried out at a temperature in the range from 100 to 199°C. A method of preparing polymers or copolymers of methacrylic acid or methacrylic acid esters is also described.
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Page/Page column 25
(2013/11/18)
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- PROCESS FOR THE PRODUCTION OF METHACRYLIC ACID AND ITS DERIVATIVES AND POLYMERS PRODUCED THEREFROM
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A process for the production of methacrylic acid is described. The process comprises the base catalysed decarboxylation of at least one or a mixture of dicarboxylic acids selected from itaconic, citraconic or mesaconic acid. The decarboxylation is carried out in the range greater than 240 and up to 275° C. to provide high selectivity. The methacrylic acid product may be esterified to produce an ester. A method of preparing polymers or copolymers of methacrylic acid or methacrylic acid esters using the process is also described. Optionally, the process may be preceded with a decarboxylation and, if necessary, a dehydration step on a source of pre-acid such as citric acid or isocitric acid.
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- A three-enzyme system involving an ene-reductase for generating valuable chiral building blocks
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The use of ene-reductase (ERED) enzymes for the asymmetric reduction of olefins offers a green, renewable alternative to metal-catalysed asymmetric reduction. We report herein the first example of an ERED-catalysed enantiospecific reduction carried out at large scale using a carbonyl reductase (CRED) enzyme in the cofactor recycle. This reaction has been paired with a hydrolase-mediated regioselective ester hydrolysis to generate a valuable chiral building block using a straightforward one-pot process. Copyright
- Mangan, David,Miskelly, Iain,Moody, Thomas S.
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p. 2185 - 2190,6
(2020/09/02)
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- Exploration of the molecular origin of the azinomycin epoxide: Timing of the biosynthesis revealed
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(Equation Presented) Streptomyces sahachiroi whole cell feeding experiments, utilizing putative precursors labeled with stable isotopes, established that the epoxide unit of the DNA cross-linked agents, azinomycin A and B, proceeds via a valine-dependent pathway and that hydroxylation and dehydration precedes formation of the terminal epoxide. Sodium 3-methyl-2-oxobutenoate, formed through a transimination reaction, was shown to be the penultimate precursor incorporated into the azinomycin epoxide.
- Sharma, Vasudha,Kelly, Gilbert T.,Watanabe, Coran M. H.
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supporting information; experimental part
p. 4815 - 4818
(2009/05/31)
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- Alkaline oxidative degradation of diphenylmethane structures - Activation energy and computational analysis of the reaction mechanism
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A diphenylmethane model compound (2,2′-methylenebis[6-methoxy-4-methylphenol]) and residual kraft lignin were treated with alkaline hydrogen peroxide. Kinetic data for the disappearance of the model and the diphenylmethane structures in the residual ligni
- Jurasek,Kristofova,Sun,Argyropoulos
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p. 1394 - 1401
(2007/10/03)
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- The effect of metal ions on the reaction of hydrogen peroxide with Kraft lignin model compounds
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Peroxide bleaching is significantly affected by transition and alkaline earth metals. Isolating the effects of different transition and alkaline earth metals on the reactions of peroxide with different representative lignin structures allows the separation of the positive from the negative contributions of these metal ions. In this work, five monomeric or dimeric phenolic lignin model compounds were treated with alkaline hydrogen peroxide in the absence or presence of Mn2+, Cu2+, Fe3+, and Mg2+. We followed the disappearance of the starting material and the progress of demethylation, radical coupling and oxalic acid formation were followed. Transition metals increased the reactivities of all the lignin model compounds with hydrogen peroxide in the order Mn2+ > Cu2+ > Fe3+, which is the same as the order of activity toward peroxide decomposition while Mg2+ stabilized the system. Demethylation, radical coupling, and oxalic acid formation were all increased by the presence of transition metals in the system and decreased by the addition of Mg2+. The acceleration of the total degree of reaction and of the demethoxylation reactions improves peroxide bleaching, but the increase in the radical coupling reactions can affect the further bleachability of pulp while the increase in the formation of oxalic acid could lead to a greater probability of scaling.
- Sun, Yujun,Fenster, Michael,Yu, Annie,Berry, Richard M.,Argyropoulos, Dimitris S.
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p. 667 - 675
(2007/10/03)
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- An EPR investigation into the reactions of alkaline hydrogen peroxide with cyanamide
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Free-radical involvement in an alkaline hydrogen peroxide/cyanamide system has been demonstrated using electron paramagnetic resonance (EPR) spectroscopy. A stable free radical is formed which shows coupling to two pairs of equivalent 14N nuclei (a14N1 = 7.30, a14N2 = 2.13 G). Both hydroxyl and carbon-centered radicals have been trapped with 5,5-dimethyl-4,5-dihydro-3H-pyrrole N-oxide (DMPO) (DMPO-OH: aH= aN = 14.9 G, DMPO-C: aH = 24.0, aN = 16.4 G). The presence of HOO. has been inferred based on the absence of reactivity in the presence of superoxide dismutase. Involvement of superoxide and cyanamide radicals has been demonstrated by the formation of ring-opened and cyanamide coupled products obtained from reactions of alkaline hydrogen peroxide-cyanamide with substituted aromatic compounds.
- Kadla, John F.,Cornman, Charles R.
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p. 2309 - 2313
(2007/10/03)
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- Dicarboxylic Acids Link Proton Transfer Across a Liquid Membrane to the Synthesis of Acyl Phosphates. A Model for P-Type H(+)-ATPases
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H(+)-ATPases are ion pumps that link proton transfer across cell membranes to the synthesis or hydrolysis of ATP.A current research goal is to understand the molecular-level mechanism of this linking.We present a chemical model that mimics some features of H(+)-ATPases by linking proton transfer across a liquid membrane to the synthesis of acyl phosphates using carboxylic acid anhydride intermediates.Citraconic acid (cis-2-methyl-2-butenedioic acid) accelerated the transfer of protons from a pH 0.3 solution across a chloroform liquid membrane to a pH 10 solution.The mechanism involved spontaneous formation of a small amount of citraconic anhydride (0.6percent) in the pH 0.3 layer.This anhydride partitioned into the chloroform layer and diffused to the pH 10 layer, where it hydrolyzed, generating two protons.When the pH 10 layer contained phosphate (1.0 M), some of the citraconic anhydride reacted with phosphate to form citraconyl phosphate, 5.0percent yield.In separate experiments, we confirmed that citraconyl phosphate had high phosphoryl donor potential by reacting it with morpholine to form a phosphoramidate (11.5percent yield) or with fluoride to form fluorophosphonate (32percent yield).To demonstrate the link between an acyl phosphate and a proton gradient in the reverse direction, we used succinyl phosphate, whose hydrolysis occurs in two steps: formation of succinic anhydride, which consumes protons, followed by hydrolysis of succinic anhydride, which releases protons.We generated a pH gradient by carrying out these two steps in separate solutions.Hydrolysis of succinyl phosphate (3.9 mmol) at pH 6.00 started with a increase in pH to 6.16 (0.59 mmol of H(+) consumed) caused by the formation of succinic anhydride.We extracted this anhydride with dichloromethane and transferred it to a separate solution at pH 6.05.Hydrolysis of the anhydride released protons (0.36 mmol), decreasing the pH to 5.23.Our model suggests that H(+)-ATPases could use acyl phosphates and carboxylic acid anhydride intermediates to link proton transfer to ATP synthesis or hydrolysis.
- Colton, Ian J.,Kazlauskas, Romas J.
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p. 3626 - 3635
(2007/10/02)
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- Oxidation of Creosol with Oxygen in Alkaline Aqueous Solution. Model Experiments on Oxygen Pulping of Wood
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Reaction of creosol (2-methoxy-4-methyl-phenol) with oxygen in alkaline aqueous solution gave several neutral and acidic compounds which were identified.By quantitative determination of the degradation products an evaluation of the degradation pathways was possible. - Keywords: Cyclohexadienons as intermediates; Oxygen bleaching; Oxygen pulping; Phenol oxidation; Gas chromatography of methyl esters
- Fricko, Paul,Holocher-Ertl, Martin,Kratzl, Karl
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p. 1025 - 1042
(2007/10/02)
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- The Reactions of Lignin with Alkaline Hydrogen Peroxide. Part IV. Products from the Oxidation of Quinone Model Compounds
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Simple para- and orhto-quinoid structures related to lignin have been oxidized with hydrogen peroxide under mild alkaline conditions.Most of the reaction products, i.e. carboxylic acids formed by oxidative cleavage of the quinoid ring together with acids formed by more extensive degradation of the starting materials, were identified after conversion into esters.In addition, small amounts of hydroxylated quinones were found.Mechanisms for the formation of these products are suggested and the significance of the results for the bleaching of mechanical pulps with hydrogen peroxide is briefly discussed.
- Gellerstedt, Goeran,Hardell, Hanne-Lise,Lindfors, Eva-Lisa
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p. 669 - 674
(2007/10/02)
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- Preparation of citraconic acid
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High purity citraconic acid is prepared in good yield by the thermolysis, in the presence of a catalyst, of citramalic acid, 3-methylmalic acid, paraconic acid, mesaconic acid and mixtures thereof.
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