- The electron stimulated chemistry of methyl lactate on Cu(1 1 1)
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The electron stimulated chemistry of monolayers of (R)/(S)-methyl lactate ((S)/(R)-MLAc) adsorbed on Cu(1 1 1) has been investigated. Monolayers of MLAc undergo highly efficient electron stimulated processes predominately desorption, but also a significant fraction is converted to an adsorbed alkoxide moiety through the selective cleavage of the O-H bond. The efficiency of the depletion of the adsorbed MLAc state and the absence of significant non-selective fragmentation contrasts with previous studies of the electron beam irradiation of monolayers of oxygen containing organic molecules.
- Fleming,Kadodwala
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Read Online
- The Oxidation of Methacrylic Acid Esters with H2O2 in the Presence of Chromium Catalysts. A Novel Route to Pyruvic Acid Esters
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The oxidation of methacrylic acid esters to pyruvic acid esters was carried out with aqueous H2O2 in CH3CN in the presence of a catalytic amount of chromium compounds such as Cr(III)(acac)3, chromium salts, and chromic acid.The oxidation of methyl methacrylate in the presence of chromic acid and triethylamine (1:1) gave an 82 percent conversion with a 72 percent selectivity to methyl pyruvate at 40 deg C for 20 h.
- Inoue, Masami,Uragaki, Toshitaka,Kashiwagi, Hiroshi,Enomoto, Saburo
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Read Online
- Metal-Free Synthesis of Polysubstituted Imidazolinone Through Cyclization of Amidines with 2-Substituted Acrylates
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Polysubstituted imidazolinones were synthesized in a facile metal-free cascade nucleophilic cyclization of easily available amidines and 2-substituted acrylates. This protocol is distinguished by simple, mild, and catalyst-free reaction conditions with a broad substrate scope, affording the desired products in moderate to good yields and providing an efficient strategy for synthesis of polysubstituted imidazolinone.
- Liu, Zhen,Zhang, Yan-Shun,Wei, Yin,Shi, Min
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supporting information
p. 1093 - 1099
(2020/02/27)
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- Conversion of Dihydroxyacetone to Methyl Pyruvate Catalyzed by Hybrid Molecular Sieves at Low Temperature: A Strategy for the Green Utilization of Glycerol
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Abstract: Methyl pyruvate (MPA) was synthesized from dihydroxyacetone (DHA), the oxidation product of glycerol, over Sn-β and TS-1 hybrid molecular sieves at low temperature. Sn-β and TS-1 provide the active sites for conversion of DHA to methyl lactate (MLA) and oxidation of MLA to MPA, respectively. Synergism of Lewis acid sites on Sn-β and TS-1 realize the production of MPA from DHA. After optimization, 71% yield of MPA can be obtained under 50?°C. This is the first report for the synthesis of MPA from DHA directly. Graphic Abstract: [Figure not available: see fulltext.].
- Luo, Qianqian,Lu, Tianliang,Xu, Jun,Yang, Xiaomei,Zhou, Lipeng
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p. 1641 - 1649
(2019/12/24)
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- Novel synthesis method of alpha-carbonyl acid ester
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The invention discloses a novel synthesis method of alpha-carbonyl acid ester. The method comprises the following steps: carrying out chlorination reaction on an alpha-methylene-containing nitrile compound and chlorine to obtain dichloronitrile, reacting the dichloronitrile product in a sulfuric acid and water system to obtain formyl cyanide, then acquiring an imino sulfate compound in the same reaction system, and finally performing esterification to obtain the target product. The adopted reaction raw materials are wide in sources and low in price, highly toxic solid sodium cyanide can be prevented from being used in the prior art, the method is environmentally friendly, and the method is easy to operate, mild in condition and easy to industrialize.
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Paragraph 0016; 0050; 0054-0055
(2020/07/21)
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- Novel effect of zinc nitrate/vanadyl oxalate for selective catalytic oxidation of α-hydroxy esters to α-keto esters with molecular oxygen: An in situ ATR-IR study
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Selective oxidation of α-hydroxy esters is one of the most important methods to prepare high value-added α-keto esters. An efficient catalytic system consisting of Zn(NO3)2/VOC2O4 is reported for catalytic oxidation of α-hydroxy esters with molecular oxygen. Up to 99% conversion of methyl DL-mandelate or methyl lactate could be facilely obtained with high selectivity for its corresponding α-keto ester under mild reaction conditions. Zn(NO3)2 exhibited higher catalytic activity in combination with VOC2O4 compared with Fe(NO3)3 and different nitric oxidative gases were detected by situ attenuated total reflection infrared (ATR-IR) spectroscopy. UV-vis and ATR-IR results indicated that coordination complex formed in Zn(NO3)2 in CH3CN solution was quite different from Fe(NO3)3; it is proposed that the charge-transfer from Zn2+ to coordinated nitrate groups might account for the generation of different nitric oxidative gases. The XPS result indicate that nitric oxidative gas derived from the interaction of Zn(NO3)2 with VOC2O4 could be in favor of oxidizing VOC2O4 to generate active vanadium (V) species. It might account for different catalytic activity of Zn(NO3)2 or Fe(NO3)3 combined with VOC2O4. This work contributes to further development of efficient aerobic oxidation under mild reaction conditions.
- Ju, Yongwei,Du, Zhongtian,Xiao, Chuhong,Li, Xingfei,Li, Shuang
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supporting information
(2019/04/05)
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- Method for preparing keto ester by catalytic oxidation of hydroxy ester (by machine translation)
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The invention relates to a method, in particular to a method for preparing ketoester by catalytic oxidation of hydroxy ester. Belong to high added value's fine chemicals technical field. The method uses molecular oxygen as an oxygen source, uses a vanadium-based nitrogen-doped carbon material as a catalyst, and selectively oxidizes hydroxyl ester to a ketone ester in a liquid phase solvent, and specifically is: a catalyst, α - hydroxyl ester, a liquid phase 40 - 180 °C reaction solvent are put into a high-pressure reactor, oxygen source, closed reaction kettle, stirring, heating and temperature raising . reaction time 0 - 12h obtains a product. Compared with a traditional pyruvic acid esterification method and the like, the invention, compared with the traditional pyruvic acid esterification method and the like. The method is mild in reaction condition, high, the conversion rate of the raw materials and the product selectivity are high, and the method has important application prospects. (by machine translation)
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Paragraph 0024; 0025; 0026; 0027; 0028; 0029; 0030-0050
(2019/10/01)
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- Base-free conversion of glycerol to methyl lactate using a multifunctional catalytic system consisting of Au-Pd nanoparticles on carbon nanotubes and Sn-MCM-41-XS
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Multifunctional catalytic systems consisting of physical mixtures of (i) bimetallic Au-Pd nanoparticles (average size of 3-5 nm) supported on functionalised carbon nanotubes (CNTs) and (ii) Sn-MCM-41 nanoparticles (50-120 nm), were synthesised and investigated for the base-free, selective conversion of glycerol to methyl lactate in a batch reactor. The catalysts were characterised by means of transmission electron microscopy, N2-physisorption, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and by Boehm titration. The catalyst based on bimetallic AuPd/CNTs showed much higher activity than the monometallic Au or Pd counterparts, thus indicating synergetic effects. Functionalisation of the CNTs by oxidative treatments had a positive effect on catalyst performance, which was correlated to the observed increase in surface acidity and hydrophilicity. The highest yield of methyl lactate achieved in this work was 85% at 96% glycerol conversion (140 °C, 10 h at 30 bar air), which is the highest yield ever reported in the literature so far. Insights in the reaction pathway were obtained by monitoring the conversion-time profiles for intermediates and their possible role as inhibitors. Batch recycling experiments demonstrated the excellent reusability of the catalyst.
- Tang, Zhenchen,Boer, Dina G.,Syariati, Ali,Enache, Mihaela,Rudolf, Petra,Heeres, Hero J.,Pescarmona, Paolo P.
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p. 4115 - 4126
(2019/08/12)
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- Oxidative functionalization of aliphatic and aromatic amino acid derivatives with H2O2 catalyzed by a nonheme imine based iron complex
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The oxidation of a series of N-acetyl amino acid methyl esters with H2O2 catalyzed by a very simple iminopyridine iron(ii) complex 1 easily obtainable in situ by self-assembly of 2-picolylaldehyde, 2-picolylamine, and Fe(OTf)2 was investigated. Oxidation of protected aliphatic amino acids occurs at the α-C-H bond exclusively (N-AcAlaOMe) or in competition with the side-chain functionalization (N-AcValOMe and N-AcLeuOMe). N-AcProOMe is smoothly and cleanly oxidized with high regioselectivity affording exclusively C-5 oxidation products. Remarkably, complex 1 is also able to catalyze the oxidation of the aromatic N-AcPheOMe. A marked preference for the aromatic ring hydroxylation over Cα-H and benzylic C-H oxidation was observed, leading to the clean formation of tyrosine and its phenolic isomers.
- Ticconi, Barbara,Colcerasa, Arianna,Di Stefano, Stefano,Lanzalunga, Osvaldo,Lapi, Andrea,Mazzonna, Marco,Olivo, Giorgio
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p. 19144 - 19151
(2018/05/31)
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- Green synthesizing process for pyruvate
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The invention provides a green synthesizing process for pyruvate. Multi-phase catalysis reaction is adopted, a catalyst can be recycled, moreover, catalysis reaction does not need a solvent, reactionconditions are mild, produced wastes are less, and energy conservation and environmental protection are achieved.
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Paragraph 0031; 0032; 0033
(2018/04/27)
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- Method for preparing pyruvate through liquid-phase catalytic oxidation of lactate
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The invention provides a method for preparing pyruvate through liquid-phase catalytic oxidation of lactate. The method comprises the following steps: mixing the lactate, a compound catalyst, an oxidant and a reaction solvent and putting a mixture into a reaction container; after mounting the reaction container, starting cooling water and condensing and refluxing, wherein the compound catalyst comprises metal halide and a solid acid catalyst; stirring and raising the temperature to reaction temperature; reacting for certain time at constant temperature; decompressing and distilling to remove the reaction solvent; washing with water to remove an inorganic catalyst; extracting a product by utilizing dichloromethane; decompressing and distilling to remove the dichloromethane to obtain a product, i.e., the lactate. Compared with synthesis methods including a tartrate hydrolysis method, a pyruvate esterification method and the like, the method has the advantages of few reaction steps, moderate reaction conditions, green and environment-friendly reaction process, cheap and efficient catalyst and relatively high conversion rate of raw materials and product selectivity; the method has a relatively good application prospect and relatively high practical value.
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Paragraph 0030-0035; 0037-0078
(2018/12/13)
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- Catalytic Gas-Phase Production of Lactide from Renewable Alkyl Lactates
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A new route to lactide, which is a key building block of the bioplastic polylactic acid, is proposed involving a continuous catalytic gas-phase transesterification of renewable alkyl lactates in a scalable fixed-bed setup. Supported TiO2/SiO2 catalysts are highly selective to lactide, with only minimal lactide racemization. The solvent-free process allows for easy product separation and recycling of unconverted alkyl lactates and recyclable lactyl intermediates. The catalytic activity of TiO2/SiO2 catalysts was strongly correlated to their optical properties by DR UV/Vis spectroscopy. Catalysts with high band-gap energy of the supported TiO2 phase, indicative of a high surface spreading of isolated Ti centers, show the highest turnover frequency per Ti site.
- De Clercq, Rik,Dusselier, Michiel,Makshina, Ekaterina,Sels, Bert F.
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supporting information
p. 3074 - 3078
(2018/03/13)
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- A β-Carbon elimination strategy for convenient: In situ access to cyclopentadienyl metal complexes
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The electronic and steric properties of tailored cyclopentadienyl (Cp) ligands are powerful handles to modulate the catalytic properties of their metal complexes. This requires the individual preparation, purification and storage of each ligand/metal combination. Alternative, ideally in situ, complexation protocols would be of high utility. We disclose a new approach to access Cp metal complexes. Common metal precursors rapidly react with cyclopentadienyl carbinols via β-carbon eliminations to directly give the Cp-metal complexes. An advantage of this is the direct and flexible use of storable pre-ligands. No auxiliary base is required and the Cp complexes can be prepared in situ in the reaction vessel for subsequent catalytic transformations.
- Smits,Audic,Wodrich,Corminboeuf,Cramer
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p. 7174 - 7179
(2017/10/05)
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- Process for the preparation of pyruvic acid methyl ester (by machine translation)
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The invention discloses a method for the preparation of methyl pyruvate, comprising the following steps: the pyruvate, methanol and mixed benzosulfonate heating to reflux, the quality of the pyruvic acid percentage is not more than 8% reaction stop; the methanol in the mixed solution is removed; then adding ethanol and benzene, water in the solution is removed; then heating takes off the benzene and ethanol, is pyruvic acid methyl ester. The invention uses the pyroracemic acid and methanol as the raw material, as catalyst benzosulfonate, reacted directly, the end point of the reaction of the mixed solution of pyruvic acid in the mass percentage is not more than 8%, and removed in a mixed solution of methanol and water, the yield of the pyruvic acid methyl ester prepared high, is friendly to the environment and having high purity; and simple operation, raw materials are easy, is suitable for industrial mass production. (by machine translation)
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Paragraph 0034; 0035
(2017/04/08)
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- OXIDATIVE DEHYDROGENATION OF LACTATE ESTERS TO PYRUVATE ESTERS
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The present invention relates to a simple one step oxidative dehydrogenation process for the synthesis of alkyl pyruvate with 100% selectivity towards alkyl pyruvate comprising reacting an alkyl lactate in the presence of catalyst at the temperature ranging from 25-100°C for the time period ranging from 5 to 40 hours in an organic solvent and hydrogen peroxide to afford alkyl pyruvate.
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Page/Page column 8
(2017/01/31)
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- A catalytic conversion method for preparing pyruvate ester of lactic acid (by machine translation)
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A method for preparing pyruvate through catalytic conversion of lactic acid is provided; according to the method, with oxygen or air as an oxidant, alcohol as a solvent, and molybdovanadophosphoric heteropoly acid and/or tungstovanadophosphoric heteropoly acid as a catalyst, and by coupling of a catalytic oxidation reaction and an esterification reaction, lactic acid is converted into pyruvate by one step. The method directly adopts oxygen or air as the oxidant and is green and safe; the used raw material lactic acid is obtained directly from conversion of biomass resources, moreover, the reaction conditions are mild, and the method has important application prospects.
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Paragraph 0017
(2016/10/10)
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- Atmospheric Degradation of CH2=C(CH3)C(O)OCH3 Initiated by OH Radicals: Mechanistic Study and Quantification of CH3C(O)C(O)OCH3 in NOx Free Air
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The product distribution of the gas-phase reaction of OH radicals with methyl methacrylate (CH2=C(CH3)C(O)OCH3, MMA) in the absence of NOx was studied at 298 K and atmospheric pressure of air. The experiments were performed in a Teflon chamber using solid-phase microextraction (SPME) with GC-MS and GC-FID for product identification and quantification, respectively. In the absence of NOx, methyl pyruvate (CH3C(O)C(O)OCH3) was identified with a yield of 76 ± 13% in accordance with the decomposition of the 1,2-hydroxyalkoxy radicals formed. In addition, a detailed quantum chemical study of the degradation of MMA was performed by density functional theory (DFT) methods using the MPWB1K functional. This calculation suggests that formation of methyl pyruvate, from C1-C2 scission of 1,2-hydroxyalkoxy radical, is kinetically and thermodynamically the most favorable reaction path taking into account the electronic properties of reaction intermediates and transition states. The difference observed on the degradation mechanism of MMA in the presence and absence of NOx was explained in terms of the associated thermochemistry. Furthermore, this study propose that reaction between peroxy radical (RO2?) and hydroxyl radical (OH) became relevant at NOx-free environments. This statement is in agreement with recent studies concerning small peroxy radicals such as CH3OO?.
- Gibilisco, Rodrigo G.,Uranga, Jorge G.,Santiago, Ana N.,Teruel, Mariano A.
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p. 8775 - 8783
(2015/09/01)
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- Reactions of hydroxyl-containing compounds with tert-butyl hydroperoxide in the presence of chromium tetra-tert-butoxide
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Primary and secondary aliphatic, alkylaromatic, cyclic, and organoelement alcohols are efficiently oxidized by tert-butyl hydroperoxide in the presence of both equimolar and catalytic quantities of chromium tetra-tert-butoxide (C6H6, 20°C). α-Diols containing tertiary hydroxyl groups interact with this system via oxidative splitting of the carbon scaffold. The oxidation includes the stages of formation and decomposition of chromium-containing peroxy compounds. Further transformations of the carbonyl compounds depend on the structure of radicals in the molecules.
- Stepovik,Zaburdaeva,Fukin,Karaghiosoff
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p. 2547 - 2559
(2015/12/30)
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- PROCESS FOR PRODUCING CARBOXYLIC ACID ESTER
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The present invention relates to a process for producing a carboxylic acid ester, comprising a step of oxidizing an aldehyde by mixing an alcohol, carbon dioxide, the aldehyde and at least one compound selected from the group consisting of compounds represented by the formulae (2-1) and (2-2): wherein R2 represents an alkyl group optionally having a substituent or the like; R3 and R4 each independently represents an alkyl group optionally having a substituent or the like or R3 and R4 are linked together to form a divalent hydrocarbon group optionally having a substituent or the like; Y represents a group of -S- or a group of -N(R5)-, wherein R5 represents an alkyl group optionally having a substituent or the like, or R5 is linked to R4 to form a divalent hydrocarbon group optionally having a substituent; and R8 represents an alkyl group.
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Page/Page column 43
(2012/03/26)
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- PROCESS FOR PRODUCING CARBOXYLIC ACID ESTER
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An object of the present invention is to provide a new process which can produce a carboxylic acid ester from an aldehyde. The object is achieved by a process for producing a carboxylic acid ester, including the step of mixing a compound represented by the formula (2-1): (wherein R2 represents an alkyl group optionally having a substituent, or the like; R3 and R4 each represent independently an alkyl group optionally having a substituent, or the like, or R3 and R4 are taken together to form a divalent hydrocarbon group optionally having a substituent, or the like; Y represents a group represented by -S- or a group represented by -N(R5)-; R5 represents an alkyl group optionally having a substituent, or the like, or R5 is taken together with R4 to form a divalent hydrocarbon group optionally having a substituent; and X- represents an anion), a base, an alcohol, oxygen and an aldehyde to oxidize the aldehyde.
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Page/Page column 52-53
(2013/02/28)
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- PROCESS FOR PRODUCING ALPHA-KETOCARBOXYLIC ACID
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The present invention relates to a process for producing an α-ketocarboxylic acid, comprising a step of oxidizing an α-ketoaldehyde by mixing a base, carbon dioxide, the α-ketoaldehyde and a compound represented by formula (2-1).
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Page/Page column 46
(2012/01/14)
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- The synthesis and crystal determination of 3-hydroxy-4-(4-methoxyphenyl)-5- (2-nitrophenyl)furan-2(5H)-one
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The title compound, C17H13NO6, was synthesized and structurally characterized by elemental analysis, MS, 1H NMR and single crystal X-ray diffraction. It crystallizes in monoclinic system space group C 2/c with a = 27.981(6) A, b = 12.996(3) A, c = 8.0900(16) A, β = 91.06(3)°, V = 2941.4(10) A3, Z = 8, R 1 = 0.0675, wR 2 = 0.1626, and T = 298(2) K. The X-ray structure determination revealed that the center furanone ring is nearly coplanar with p-methoxybenzene ring and forms a dihedral angle of 87.2(1)° with the nitrobenzene ring. O-H...O Intermolecular hydrogen bonds link pairs of molecules into centrosymmetric dimers, making a graph set motif of R 2 2 (10). The dimers are further assembled into a chain of edge-fused R 4 4 (34) rings running along the [001] direction. The final three-dimensional supramolecular architecture is stabilized by weak π-π interactions. Graphical Abstract: The dimers were assembled into a chain of edge-fused R 4 4 (34) rings running along the [001] direction and a co-chain is formed with an "x" pattern of the cross section.
- Xiao, Zhu-Ping,Peng, Zhi-Yun,Liu, Zhu-Xiang,Chen, Li-Hua,Zhu, Hai-Liang
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experimental part
p. 649 - 653
(2011/12/02)
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- Atmospheric chemistry of two biodiesel model compounds: Methyl propionate and ethyl acetate
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The atmospheric chemistry of two C4H8O2 isomers (methyl propionate and ethyl acetate) was investigated. With relative rate techniques in 980 mbar of air at 293 K the following rate constants were determined: k(C2H5C(O)OCH3 + Cl) = (1.57 ± 0.23) × 10-11, k(C2H5C(O) OCH3 + OH) = (9.25 ± 1.27) × 10-13, k(CH 3C(O)OC2H5 + Cl) = (1.76 ± 0.22) × 10-11, and k(CH3C(O)OC2H5 + OH) = (1.54 ± 0.22) × 10-12 cm3 molecule -1 s-1. The chlorine atom initiated oxidation of methyl propionate in 930 mbar of N2/O2 diluent (with, and without, NOx) gave methyl pyruvate, propionic acid, acetaldehyde, formic acid, and formaldehyde as products. In experiments conducted in N 2 diluent the formation of CH3CHClC(O)OCH3 and CH3CCl2C(O)OCH3 was observed. From the observed product yields we conclude that the branching ratios for reaction of chlorine atoms with the CH3-, -CH2-, and -OCH3 groups are 9 ± 2%, respectively. The chlorine atom initiated oxidation of ethyl acetate in N2/O 2 diluent gave acetic acid, acetic acid anhydride, acetic formic anhydride, formaldehyde, and, in the presence of NOx, PAN. From the yield of these products we conclude that at least 41 ± 6% of the reaction of chlorine atoms with ethyl acetate occurs at the -CH2- group. The rate constants and branching ratios for reactions of OH radicals with methyl propionate and ethyl acetate were investigated theoretically using transition state theory. The stationary points along the oxidation pathways were optimized at the CCSD(T)/cc-pVTZ//BHandHLYP/aug-cc-pVTZ level of theory. The reaction of OH radicals with ethyl acetate was computed to occur essentially exclusively (～99%) at the -CH2- group. In contrast, both methyl groups and the -CH2- group contribute appreciably in the reaction of OH with methyl propionate. Decomposition via the α-ester rearrangement (to give C2H5C(O)OH and a HCO radical) and reaction with O 2 (to give CH3CH2C(O)OC(O)H) are competing atmospheric fates of the alkoxy radical CH3CH2C(O)OCH 2O. Chemical activation of CH3CH2C(O)OCH 2O radicals formed in the reaction of the corresponding peroxy radical with NO favors the α-ester rearrangement.
- Andersen, Vibeke F.,Berhanu, Tesfaye A.,Nilsson, Elna J. K.,Jorgensen, Solvejg,Nielsen, Ole John,Wallington, Timothy J.,Johnson, Matthew S.
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experimental part
p. 8906 - 8919
(2011/10/17)
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- Kinetics and products of gas-phase reactions of ozone with methyl methacrylate, methyl acrylate, and ethyl acrylate
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The kinetics and products of the gas-phase reactions of ozone with methyl methacrylate, methyl acrylate, and ethyl acrylate have been investigated at 760 Torr total pressure of air and 294 ± 2 K. The rate coefficients obtained (in cm3 molecule-1 s-1 units) were as follows: k(methyl methacrylate) = (6.7 ± 0.9) × 10-18, k(methyl acrylate) = (0.95 ± 0.07) × 10-18, and k(ethyl acrylate) = (1.3 ± 0.1) × 10-18. In addition to formaldehyde being observed as a product of the three reactions, the other major reaction products were methyl pyruvate from reaction of ozone with methyl methacrylate, methyl glyoxylate from reaction of ozone with methyl acrylate, and ethyl glyoxylate from reaction of ozone with ethyl acrylate. Possible reaction mechanisms leading to the observed products are presented and discussed.
- Bernard,Eyglunent,Daele,Mellouki
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experimental part
p. 8376 - 8383
(2011/02/16)
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- PROCESS FOR THE SAFE OZONOLYSIS OF ORGANIC COMPOUNDS IN FLAMMABLE SOLVENTS
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An improved process for the safe ozonolysis of unsaturated, organic carbon compounds having one or more olefinic or aromatic double bonds in the molecule in flammable solvents for the preparation of mono- or biscarbonyl or hydroxy compounds, in which ozonolysis is carried out with the use of an ozone-carrying inert gas/O2 stream, in which the oxygen concentration in the inert gas/O2 stream is above the known limiting oxygen concentration of the homogeneous fuel/gas mixtures and below the safety-critical limiting oxygen concentration of the heterogeneous mixture of the liquid fuel and oxygen-containing gas which is dependent on the reaction conditions and at which ignition and flame propagation no longer take place.
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Page/Page column 22-23
(2008/12/06)
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- Catalyst-free gas-phase epoxidation of alkenes
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Butadiene, styrene, cyclohexene, allyl acetate, methyl methacrylate, and allyl alcohol were epoxidized in a gas-phase reaction in the absence of a catalyst. The applied oxidizing agent is ozone. With exception of allyl alcohol (selectivity to glycidol: 58%), the selectivity to the corresponding epoxide ranged from 88 to 97%. For acrylonitrile, there was no measureable conversion. Copyright
- Berndt, Torsten,Boege, Olaf
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p. 584 - 585
(2007/10/03)
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- Regioselective alkene carbon-carbon bond cleavage to aldehydes and chemoselective alcohol oxidation of allylic alcohols with hydrogen peroxide catalyzed by [cis-Ru(II)(dmp)2(H2O)2] 2+ (dmp = 2,9-dimethylphenanthroline)
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(Chemical Equation Presented) [cis-Ru(II)(dmp)2(H 2O)2]2+ (dmp = 2,9-dimethylphenanthroline) was found to be a selective oxidation catalyst using hydrogen peroxide as oxidant. Thus, primary alkenes were very efficiently oxidized via direct carbon-carbon bond cleavage to the corresponding aldehydes as an alternative to ozonolysis. Secondary alkenes were much less reactive, leading to regioselective oxidation of substrates such as 4-vinylcyclohexene and 7-methyl-1,6-octadiene at the terminal position. Primary allylic alcohols were chemoselectively oxidized to the corresponding allylic aldehydes, e.g., geraniol to citral.
- Kogan, Vladimir,Quintal, Miriam M.,Neumann, Ronny
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p. 5039 - 5042
(2007/10/03)
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- Method for preparing chiral diphosphines
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The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
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- Kinetics and mechanism for oxime formation from methyl pyruvate
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Rate and equilibrium constants for methyl pyruvate oxime formation were determined as a function of pH over the range 0-7 in aqueous solution at 30°C and ionic strength 0.5 by spectrophotometric methods. The reaction occurs with rate-determining carbinolamine dehydration over the entire range of pH investigated. Carbinolamine dehydration is not susceptible to detectable general acid-base catalysis by a carboxylic acid buffer or hydroxylamine/hydroxylammonium ion buffer. Specific acid catalysis for carbinolamine formation is dominant at pH values below 5. Above that value, a pH-independent, water-catalyzed reaction becomes apparent. The pH-independent carbinolamine dehydration is unusually important with this substrate. Copyright
- Cordova,Peraza,Calzadilla,Malpica
-
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- Facile Synthesis of α-Ketocarbonyl Compounds from α-Hydroxycarbonyl Compounds
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Various α-ketocarbonyl compounds were obtained in excellent yields under mild condition from the reaction of the corresponding α-hydroxycarbonyl compounds with sodium hypobromite in the presence of HCl catalyst.
- Chang, Hae Sung,Woo, Jae Chun,Lee, Kyoung Mo,Ko, Young Kwan,Moon, Surk-Sik,Kim, Dae-Whang
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- Practical Os/Cu-cocatalyzed air oxidation of allyl and benzyl alcohols at room temperature and atmospheric pressure
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(equation presented) A new protocol for the oxidation of primary and secondary allyl and benzyl alcohols at room temperature and using 1 atm of air is described. The procedure uses low loadings of copper salts and osmium tetroxide, which is activated with quinuclidine and prereduced with an alkene. Chemoselectivity for allyl and benzyl alcohols is very high, no overoxidation is observed, and the reaction takes place under neutral conditions.
- Muldoon, John,Brown, Seth N.
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p. 1043 - 1045
(2007/10/03)
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- Atmospheric oxidation mechanism of methyl propionate
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Smog chamber FTIR techniques were used to study the atmospheric oxidation of methyl propionate in 740 Torr of air in the presence of NOx at 296 ± 2K. Relative rate techniques were used to measure k(OH + CH3CH2C(O)OCH3
- Cavalli,Barnes,Becker,Wallington
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p. 11310 - 11317
(2007/10/03)
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- Asymmetric hydrogenation method of a ketonic compound and derivative
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The present invention relates to a process for the asymmetric hydrogenation of a ketonic compound and derivative. The invention relates to the use of optically active metal complexes as catalysts for the asymmetric hydrogenation of a ketonic compound and derivative. The process for the asymmetric hydrogenation of a ketonic compound and derivative is characterized in that the asymmetric hydrogenation of said compound is carried out in the presence of an effective amount of a metal complex comprising as ligand an optically active diphosphine corresponding to one of the following formulae: STR1
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- Baker's Yeast-Mediated Reductions of α-Keto Esters and an α-Keto-β-Lactam. Two Routes to the Paclitaxel Side Chain
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Baker's yeast (Saccharomyces cerevisiae) has been used to reduce a series of alkyl esters derived from pyruvate and benzoylformate. Both the yield and enantioselectivities of these reductions were maximized when methyl esters were used, and the (R)-alcohols were isolated in all instances. Yeast-mediated ester hydrolysis was a significant side reaction for products derived from long-chain alcohols. In the case of ethyl benzoylformate, the addition of methyl vinyl ketone increased the enantioselectivity of the reduction. These reductions were applied to two syntheses of the paclitaxel C13 side chain [(2R,3S)-N-benzoyl-3-phenylisoserine]. In the first, a racemic α-keto-β-azido ester was reduced by whole cells of Baker's yeast to afford a diastereomeric mixture in which the desired product predominated and could be isolated chromatographically. In the second, an easily synthesized α-keto-β-lactam was reduced by yeast cells to afford the desired eis isomer as well as the undesired trans diastereomer. Substituting a yeast strain deficient in fatty acid synthase in this reduction suppressed formation of the trans diastereomer. These results suggest that a single enzyme is responsible for both the D- and L-cis-alcohols resulting from reduction of the α-keto-β-lactam. All of the yeast strains used in this project are available commercially, and these biocatalytic reductions require only common laboratory equipment.
- Kayser, Margaret M.,Mihovilovic, Marko D.,Kearns, Jeff,Feicht, Anton,Stewart, Jon D.
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p. 6603 - 6608
(2007/10/03)
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- The Hydroxyl Radical Reaction Rate Constant and Products of Methyl Isobutyrate
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The relative rate technique has been used to measure the rate coefficient for the reaction of the hydroxyl radical [OH] with methyl isobutyrate (MIB, (CH3)2CHC(=O)-O-CH3) to be (1.7 +/- 0.4) x 10-12 cm3molecule-1s-1 at 297 +/- 3 K and 1 atmosphere total pressure. To more clearly define MIB's atmospheric degradation mechanism, the products of the OH + MIB reaction were also determined. The observed products and their yields were: acetone (97 +/- 1 percent, (CH3)2C(=O)) and methyl pyruvate (MP, 3.3 +/- 0.3 percent, CH3C(=O)C(=O)-O-CH3). The products' formation pathways are discussed in light of current understanding of the atmospheric chemistry of oxygenated organic compounds.
- Wyatt, S. E.,Baxley, J. S.,Wells, J. R.
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p. 550 - 558
(2007/10/03)
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- Process for the hydroxyalkylation of a carbocyclic aromatic ether
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The present invention concerns a process for the hydroxyalkylation of a carbocyclic aromatic ether. The invention preferably relates to the preparation of 3-methoxy-4-hydroxybenzyl alcohol by the hydroxymethylation of guaiacol. It also concerns the oxidation of the hydroxyalkylated ethers obtained, in particular the oxidation of 3-methoxy-4-hydroxybenzyl alcohol to 3-methoxy-4-hydroxybenzaldehyde, commonly known as "vanillin". The process for the hydroxyalkylation of a carbocyclic aromatic ether of the invention consists of reacting the aromatic ether with a carbonyl compound in the presence of a catalyst and is characterized in that the hydroxyalkylation reaction is carried out in the presence of an effective quantity of a zeolite.
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- A selective method for the preparation of aliphatic methyl esters in the presence of aromatic carboxylic acids
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2,2-Dimethoxypropane, methanol and a catalytic amount of HCl selectively esterify aliphatic carboxylic acids, in the presence of aromatic carboxylic acids, at room temperature and in high yields.
- Rodriguez,Nomen,Spur,Godfroid
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p. 8563 - 8566
(2007/10/03)
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- Para-hydroxyalkylation of hydroxylated aromatic compounds
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Hydroxylated aromatic compounds devoid of substituents in the para-position to the hydroxyl group thereof are para-hydroxyalkylated, e.g., into optionally substituted p-hydroxymandelic acid compounds, more particularly p-hydroxymandelic acid and 3-methoxy-p-hydroxymandelic acid, by condensing same with an organic carbonyl compound in the presence of a quaternary ammonium hydroxide.
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- Oxygen Atom Transfer With Niobocene Ketenes; Baeyer-Villiger Chemistry with Unusual Regioselectivities
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Niobocene ketene complex 1 has been utilized as an oxygen atom transfer reagent, converting ketones and aldehydes to esters and carboxylic acids.The steric properties of compound 1 give rise to a series of relative migratory aptitudes that differs from those seen for peracids.The process may be rendered catalytic in 1 with methyltrifluoromethyldioxirane (4). Key Words: Baeyer-Villiger reaction, niobocene complexes, ketenes, oxygen transfer, dioxiranes
- Fermin, Maria C.,Bruno, Joseph W.
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p. 7545 - 7548
(2007/10/02)
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- Acid-catalyzed hydrolysis of 5-enolpyruvylshikimate 3-phosphate (EPSP) and some simple models of its vinyl ether functional group
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Rates of hydrolysis of the vinyl ether functional groups of 5-enolpyruvylshikimate 3-phosphate (EPSP), α-methoxyacrylic acid, and methyl α-methoxyacrylate were measured in concentrated and dilute mineral acid solutions and carboxylic acid buffers, and rate profiles were constructed from the data so obtained. The results for methyl α-methoxyacrylate show a monotonic decrease in reaction rate with decreasing solvent acidity, culminating in a first-order dependence on [H+] in dilute acids; this and solvent isotope effects on this reaction indicate that this process occurs by the conventional mechanism for vinyl ether hydrolysis involving rate-determining proton transfer from hydronium ion to the substrate. The rate profiles for EPSP and α-methoxyacrylic acid are similar to that of methyl α-methoxyacrylate in concentrated acids, but they show uncatalyzed plateaus in the region pCH+ = 1-3 that then give way to renewed acid catalysis beyond pCH = 4. Solvent isotope effects suggest that these plateaus represent reaction via ionization of the carboxylic acid groups of these substrates followed by conventional hydrolysis of the vinyl ether groups of the carboxylate ions. Analysis of the data gives pKa = 3.77 for EPSP and pKa = 3.46 for α-methoxyacrylic acid and provides rate constants which show rate-retarding substituent effects on vinyl ether hydrolysis of 16 for α-CO2-, 20 000 for α-CO2H, and 81 000 for α-CO2Me.
- Kresge, A. Jerry,Leibovitch, Mordechai,Sikorski, James A.
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p. 2618 - 2622
(2007/10/02)
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- Process for the manufacture of alkyl pyruvates
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The invention provides an improved process for the manufacture of alkyl pyruvates having general formula (I): where R represents a C1 to C8 alkyl radical, by controlled oxidation of the corresponding alkyl lactate. The process is characterized in that the controlled oxidation is carried out using an aqueous hydrogen peroxide solution in the presence of catalytic quantities of bromium.
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- About the Ozone Cleavage of Chloroprene and of 2-Chloro-3-methyl-1,3-butadiene in Methanol
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Monoozonolyses of chloroprene (1a) and of 2-chloro-3-methyl-1,3-butadiene (1b) in methanol occur with more than 90percent at the non-chlorinated double bonds to afford the corresponding α,β-unsaturated oxo compounds 2 with selectivities of 96 and 80percent respectively.The latter subsequently react with methanol, and 2a also with the complementary fragment methoxymethyl hydroperoxide (5).The α,β-unsaturated methoxy hydroperoxides 3 which have also been obtained, are less stable than similarly structured, non-α-chlorinated methoxy hydroperoxides.Diozonolyses of 1a and 1b in methanol afforded in 50-60percent the corresponding α-oxocarboxylates (21) and/or the corresponding ketals.In addition, anomalous products were obtained viz. ca. 15percent of methyl hydroxyacetate (12d) from 1a and 1b, as well as ca. 30percent of dimethyl oxalate (27b) from 1a and ca. 35percent of methyl acetate (13) from 1b.The modes of formation of these products have been postulated according to model reactions.
- Griesbaum, Karl,Meister, Martin
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p. 1573 - 1580
(2007/10/02)
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- Monoozonides of chloro-substituted conjugated dienes: preparation, stability, and some chemical reactions
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The chlorodienes (E)-4-chloro-3-methyl-1,3-hexadiene (5a), (E) and (Z)-4-chloro-2,3-dimethyl-1,3-hexadiene (5b/6b), (E,E)-5-chloro-4-methyl-2,4-heptadiene (5c), (4E)- and (4Z)-5-chloro-3,4-dimethyl-2,4-heptadiene (5d/6d), chloroprene (11a), and 2-chloro-3-methyl-1,3-butadiene (11b) are selectively ozonized at the non-chlorinated double bonds to give the corresponding monoozonides 7, 8, and 12.Further ozonolyzis of the monoozonides of 5b and of 11b in methanol as well as epoxidation of the monoozonide of 5b and subsequent reaction of the resulting chloroepoxide with AgBF4 are described.
- Griesbaum, Karl,Bandyopadhyay, Ashis R.,Meister, Martin
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p. 1553 - 1559
(2007/10/02)
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- NOVEL OXIDIZING PROPERTIES OF p-METHOXYBENZENETELLURINIC ACID ANHYDRIDE
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The title compound has proved to be a mild oxidizing agent like the corresponding telluroxide or tellurone towards thiol, phosphine, thioamide, thiourea, thionoester, and benzylic alcohol.In addition, it serves as a selective catalyst for the hydration of terminal alkyne.
- Hu, Nan Xing,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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p. 6099 - 6102
(2007/10/02)
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- REACTIONS OF FUROXANS WITH PHOSPHORUS YLIDES
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Benzofuroxan (1) reacts with phosphorus ylide 2 to give benzimidazole derivatives 8 and 10, whereas reaction of 1 with ylide 12 furnishes quinoxaline 17 via an initial Wittig-type reaction.Similarly the reaction between the furoxanoquinoxalines 19a or 19b and the ylide 2 yielded compounds 22a and 22b, respectively.In these reactions as well as in the reactions of the above furoxans with other phosphorus ylides, a significant deoxygenation of the furoxans to furazans with subsequent oxidation of the ylides is generally observed.
- Argyropoulos, N. G.,Gallos, J. K.,Nicolaides, D. N.
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p. 3631 - 3636
(2007/10/02)
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- SYNTHESIS OF DIPEROXIDES AND THEIR THERMAL DECOMPOSITION
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Diperoxides were synthesized from glycolic and lactic esters.Their thermal decomposition was realized in benzene and isopropyl alcohol, and the rate constants and apparent activation energies of the process were determined.On the basis of the kinetic data and of the nature of the isolated decomposition products a mechanism is proposed for the thermal decomposition of diperoxides.
- Kirillov, A. I.,Ivanova, L. F.,Shilov, G. I.
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p. 301 - 305
(2007/10/02)
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- Pyridoxal Methochloride Catalysis of the β-Elimination Reaction of Methyl 3-Chloroalaninate in Water
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The β-elimination reaction of methyl 3-chloroalaninate has been investigated in the absence and presence of pyridoxal methochloride (2) or pyridoxal (3).Apparently, compound 2 was about twice as effective as 3 in the catalytic reaction that proceeds via a Schiff base of substrate and 2 or 3.The pH-rate profiles for the catalytic reaction with 2 and 3 were analyzed in terms of ionization of the various Schiff base species present in solution.It was found that the reactivity of the Schiff base decreases as the ionization of the molecule progresses.The reaction mechanism and its relevance to the catalysis of pyridoxal phosphate-dependent enzymes are discussed.
- Kondo, Hiroki,Morita, Kanzi,Kitamikado, Tatsuya,Sunamoto, Junzo
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p. 1031 - 1034
(2007/10/02)
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- Specific Two-Step Decarboxylation of Copper(I,II) β-Keto Carboxylates. A Novel Type of Regulation of the Decarboxylation of β-Keto Acids
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Copper(I,II) β-keto carboxylates undergo a specific two-step decarboxylation.For example, the decarboxylation of copper(I) 1-oxocyclohexane-2-carboxylate (1) evolves CO2 in a 50percent yield in dimethylformamide (DMF) at 70 deg C.No further CO2 evolution beyond this 50percent decarboxylation occurs at 70 deg C.At a higher temperature of 120 deg C., the remaining 50percent of the CO2 is released.This specific two-step decarboxylation of 1 results from the intermediate formation of a dicopper(I) salt of the enol of 1-oxocyclohexane-2-carboxylic acid (10) which is stable to decarboxylation at 70 deg C.Compound 10 is isolated from the reaction mixture after the 50percent decarboxylation.Decarboxylations of copper(I,II) benzoylacetates, copper(I) oxaloacetate, copper(II) 1-oxo-cyclohexane-2-carboxylate, and copper(II) chloride 1-oxocyclohexane-2-carboxylate also proceed stepwise in DMF.On the other hand, copper(I,II) benzoylcyclopropane-1-carboxylates without an enolizable α-hydrogen atom evolve CO2 in a usual one-step manner.The present specific two-step decarboxylation of copper(I,II) β-keto carboxylates provides a novel type of regulation of the decarboxylation of β-keto acids and also a method of generating copper(I,II) enolate.The bearing of the two-step decarboxylation of copper(I) β-keto carboxylates on both the Cu(I)-mediated carboxylation of ketones and organic synthesis is also described.
- Tsuda, Tetsuo,Chujo, Yoshiki,Takahashi, Seiji,Saegusa, Takeo
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p. 4980 - 4987
(2007/10/02)
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- 4-Dimethylaminopyridine N-Oxide as an Efficient Oxidizing Agent for Alkyl Halides
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Various types of alkyl halides were converted into aldehydes or ketones in high yields with 4-dimethylaminopyridine N-oxide in the presence or absence of DBU.
- Mukaiyama, Shigemi,Inanaga, Junji,Yamaguchi, Masaru
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p. 2221 - 2222
(2007/10/02)
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