25087-26-7Relevant articles and documents
Selective oxidation of methacrolein to methacrylic acid on carbon catalysts
Zhou, Lilong,Sun, Ye,Li, Bin,Li, Zhengjie,Zhang, Zhikun,Yun, Jimmy,Liu, Runjing
, p. 44 - 49 (2019)
Different carbon structures (activated carbon, carbon nanotubes, graphene and graphite)were investigated for the replacement of heteropoly catalysts for the oxidation of methacrolein to methacrylic acid. Activated carbon showed the best catalytic performance with higher catalytic activity than molybdovanaphosphoric acid at lower temperatures. The catalytic performance of activated carbon was further improved by the addition of heteroatoms, such as P, B, N and S. The latter occupy the electrophilic oxygen functional groups thus preventing further oxidation of methacrylic acid and improving reaction selectivity. The best catalytic performance results were obtained on activated carbon with 10 wt% P, where methacrolein conversion, methacrylic acid selectivity and yield at 270 °C were 40.1, 70.8 and 30.3%, respectively. The results of the present work show a novel way to design non-metal catalysts for the selective oxidation of methacrolein to methacrylic acid.
Catalysis by Heteropoly Compounds. XVIII. Oxidation of Methacrylaldehyde over 12-Molybdophosphoric Acid and Its Alkali Salts
Mizuno, Noritaka,Watanabe, Tetsuji,Misono, Makoto
, p. 243 - 247 (1991)
The reaction scheme for the methacrylaldehyde oxidation over heteropoly compounds proposed previously (M.Misono et al., Proc. 7th Intl.Congr.Catal., 1980) was confirmed by 18O tracer experiments using the Pulse-MS method (combination of pulse reactor/mass spectrometer).The occurrence of direct and rapid oxygen exchange between methacrylaldehyde and the polyanion of MxH3-xPMo12O40 (M=Na, Cs, x=0-3.15) was verified under the reaction conditions.The results also suggested that this reaction is catalyzed by Broensted acid sites of the catalysts via such intermediates as (I) and/or (II) in scheme 1.It was shown that the methacrylaldehyde oxidation is a surface-type reaction and the catalytic activity is controlled by the oxidizing ability of the catalyst surface.
Direct Oxidation of Isobutane in to Methacrylic Acid and Methacrolein over Cs2.5Ni0.08-substituted H3PMo12O40
Mizuno, Noritaka,Tateishi, Masaki,Iwamoto, Masakazu
, p. 1411 - 1412 (1994)
Cs+, and Ni2+, Mn2+ or Fe3+ substitution for H+ in H3PMo12O40 greatly enhanced the catalytic activity for the title reaction and among the catalysts tested Cs2.5Ni0.08H0.34PMo12O40 gave the highest yield of methacrylic acid and methacrolein.
Kinetics of oxidation of α,β-unsaturated aldehydes by quinolinium dichromate
Chaubey, Girija S.,Das, Simi,Mahanti, Mahendra K.
, p. 204 - 208 (2003)
A series of α,β-unsaturated aldehydes (crotonaldehyde, cinnamaldehyde, acrylaldehyde, and methacrylaldehyde) were oxidized by quinolinium dichromate in sulfuric acid to the corresponding acids in 50% (v/v) acetic acid water medium. The kinetic data have been discussed with reference to the aldehyde hydration equilibria. The kinetic results support a mechanistic pathway proceeding via a rate-determining oxidative decomposition of the chromate ester of the aldehyde hydrate.
Partial oxidation of 2-methyl-1,3-propanediol to methacrylic acid: experimental and neural network modeling
Darabi Mahboub, Mohammad Jaber,Rostamizadeh, Mohammad,Dubois, Jean-luc,Patience, Gregory S.
, p. 114123 - 114134 (2016)
Methacrylic acid (MAA) is a specialty intermediate to produce methyl methacrylate (MMA), which is a monomer for poly methyl methacrylate. Current processes to MMA and MAA rely on expensive feedstocks and multi-step processes. Here we investigate the gas-phase oxidation of 2-methyl-1,3-propanediol (2MPDO) to MAA over heteropolycompounds as effective catalysts, finding that the maximum selectivity to MAA was 41% with 63% conversion of reactant at 250 °C over Cs(NH4)2PMo12O40(VO)Cu0.5. Cesium (Cs) stabilized the catalyst structure at 250 °C, and vanadium(v) and copper (Cu) played a positive role as an oxidant and promoter, respectively. A 0.3 mm nozzle atomized the liquid reactant over the catalyst surface into a μ-fluidized bed reactor. The proposed Artificial Neural Network (ANN) model predicts MAA selectivity based on 2MPDO and oxygen compositions and catalyst components (Cs, V, Cu) as independent factors. The model accounts for 97% of the variance in the data (R2 = 0.97). Vanadium as a catalyst component and oxygen concentration are the two most significant factors. Genetic algorithms (GA) coupled with ANN modeling optimized the input parameters to improve the selectivity. The selectivity to MAA over the optimized catalyst (Cs(NH4)2PMo12O40(VO)Cu0.15) and optimum feed compositions (2MPDO/O2/Ar = 13%/10%/77%) was 43% at 250 °C.
Bakulina et al.
, (1977)
Catalytic activity of V-substituted Cs2te0.2H 0.6 + xPMo12-xVxOn heteropoly compounds in selective oxidation of isobutane
Ding, Wenli,Kan, Qiubin,Liu, Heng,Liu, Lulu,Guan, Jingqi
, p. 404 - 408 (2012)
A series of Cs2Te0.2H0.6 + xPMo 12 - xVxOn (x = 0-3) heteropoly compounds has been.prepared and tested in the partial oxidation of isobutane. Catalytic tests show that at 350°C very high selectivity to methacrylic acid (60.1%) can be achieved at isobutane conversion of 12.2% over a Cs2.0Te0.2H 1.6PMo11VOn catalyst with only one molybdenum atom per.unit cell substituted by vanadium. The presence of Te4+ in the heteropoly compounds appears to interfere with the dehydrqgenation step and favor the formation of methacrolein and methacrylic acid. Pleiades Publishing, Ltd., 2012.
Development of a scalable synthesis of GSK183390A, a PPAR α/γ agonist
Oh, Lynette M.,Wang, Huan,Shilcrat, Susan C.,Hermann, Robert E.,Patience, Daniel B.,Spoors, P. Grant,Sisko, Joseph
, p. 1032 - 1042 (2007)
A scalable synthesis of GSK183390A, a PPAR α/γ agonist, is described. This synthesis is highlighted by (1) a regioselective formal 1,3-dipolar cycloaddition reaction between an enamine and a nitrile inline dipole to form a 1,3,5-trisubstmited pyrazole and (2) a regioselective amidomethylation of an o-cresol derivative using 2-chloro-JV- hydroxymethylacetamide.
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Smith,Holm
, p. 746 (1957)
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Kinetics and mechanism of the gas-phase elimination of primary, secondary and tertiary 2-acetoxycarboxylic acids
Chuchani, Gabriel,Dominguez, Rosa M.,Herize, Armando,Romero, Roman
, p. 757 - 764 (2000)
The gas-phase elimination kinetics of the title compounds were examined over the temperture range 220.1 -349.0°C and pressure range 19-120 Torr. These reactions proved to he homogeneous and unimolecular and to follow a first-order rate law. The overall rate coefficients arc expressed by the following Arrhenius equations: for 2-acetoxyacetic acid, logk1 (s-1) = (12.03 ± 0.28) - (170.8 ± 3.2) kJ mol-1 (2.303RT)-1 : for 2-acetoxypropionic acid, logk1 (s-1) = (13.16 ± 0.24) - (174.2 ± 2.6) kJ mol-1 (2.30RT)-1 : for 2-acetoxy-2-methylproponic acid, logk1 (s-1) = (13.40 ± 0.72) - (160.9 ± 5.03) kJ mol-1 (2.303RT)-1. The products of the acetoxyacids are acetic-acid, the corresponding carbonyl compound and CO gas. except for 2-acetoxy-2-methylpropionic acid. which undergoes a parallel elimination to give methacryclic acid and acetic acid. The rates of elimination are found to increase from primary to tertiary carbon bearing the acetoxy group. The mechanism appears to proceed through a discrete polar five-membered cyclic transition state, where the acidic hydrogen of the COOH assists the leaving acetoxy group, followed by the participation of the carbonyl oxygen for α-lactone formation. The unstable α-lactone intermediate decomposes rapidly into the corresponding carbonyl compound and CO gas. The importance of the acidic H of the COOH assistance in the acetoxy acid mechanisms may be revealed in the elimination kinetics of methyl 2-acetoxypropionate. This substrate was studied in the ranges 370.0-430.0°C and 36-125 Torr This reaction is homogeneous, unimolecular and follows a first-order rate law. The products are methyl acrylate and acetic acid. The rate coefficients is given by the equation logk1 (s-1) = (12.63 ± 0.35) - (201.7 ± 4.4) kJ mol-1 (2.303RT)-1. Copyright
A CATALYST AND A PROCESS FOR THE PRODUCTION OF ETHYLENICALLY UNSATURATED CARBOXYLIC ACIDS OR ESTERS
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Page/Page column 40, (2021/02/05)
The invention discloses a catalyst comprising a silica support, a modifier metal and a catalytic alkali metal. The silica support has a multimodal pore size distribution comprising a mesoporous pore size distribution having an average pore size in the range 2 to 50 nm and a pore volume of said mesopores of at least 0.1 cm3/g, and a macroporous pore size distribution having an average pore size of more than 50 nm and a pore volume of said macropores of at least 0.1 cm3/g. The level of catalytic alkali metal on the silica support is at least 2 mol%. The modifier metal is selected from Mg, B, Al, Ti, Zr and Hf. The invention also discloses a method of producing the catalyst, a method of producing an ethylenically unsaturated carboxylic acid or ester in the presence of the catalyst, and a process for preparing an ethylenically unsaturated acid or ester in the presence of the catalyst.
Ligand-controlled divergent dehydrogenative reactions of carboxylic acids via C–H activation
Wang, Zhen,Hu, Liang,Chekshin, Nikita,Zhuang, Zhe,Qian, Shaoqun,Qiao, Jennifer X.,Yu, Jin-Quan
, p. 1281 - 1285 (2021/12/10)
Dehydrogenative transformations of alkyl chains to alkenes through methylene carbon-hydrogen (C–H) activation remain a substantial challenge. We report two classes of pyridine-pyridone ligands that enable divergent dehydrogenation reactions through palladium-catalyzed b-methylene C–H activation of carboxylic acids, leading to the direct syntheses of a,b-unsaturated carboxylic acids or g-alkylidene butenolides. The directed nature of this pair of reactions allows chemoselective dehydrogenation of carboxylic acids in the presence of other enolizable functionalities such as ketones, providing chemoselectivity that is not possible by means of existing carbonyl desaturation protocols. Product inhibition is overcome through ligand-promoted preferential activation of C(sp3)–H bonds rather than C(sp2)–H bonds or a sequence of dehydrogenation and vinyl C–H alkynylation. The dehydrogenation reaction is compatible with molecular oxygen as the terminal oxidant.
