cas 431-03-8, 2,3-Butanedione | Articles data

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Nakagawa et al.
p. 269,273,274
(1960)
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Waters
(1947)
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Models for Oxygenases That Catalyze the Cleavage of Carbon-Carbon Bonds: Kinetics and Mechanism of the Decomposition of 2,3-Dimethyl-3-peroxyindolenines in Aqueous Solution
At 41 deg C in aqueous solution, 2,3-dimethyl-2-(hydroperoxy)indolenine (6) and 2,3-dimethyl-3-(methylperoxy)indolenine (7) react according to first-order kinetics to give, depending on pH, o-acetamidoacetophenone (8), 2,3-butanedione (biacetyl), or a mixture of the two in virtually quantitative yield.The pH-rate and product profiles obtained with 6 and 7 show some similarities but are not identical.With 7 as reactant the rate constant for formation of each product is characterized by a bell-shaped curve, the half-maximum points being at ca. pH 2.2 and 6 for biacetyl formation and at 6 and 7.5 for the formation of 8.Compound 6 reacts more rapidly and over a broader pH range; the overall ferst-order rate constant is at a maximum and relatively constant from pH 4 to 10, but it decreases at low and high pH.Above pH 7, 8 is the only product, but a mixture of 8 and biacetyl are formed at lower pHs.The pKas of protonated 6 and 7 were found to be 2.28 and 2.18 respectively.Studies with 18O-labeled 6 indicate that at pH 4 8 is formed with essentially 100percent of the amide group labeled, but at higher pHs, the amount of unlabeled oxygen in this position increases to a maximum of 50percent at pHs 9 to 12.6.The results with 7 can be quantitatively rationalized in terms of a mechanism that involves cis and trans isomers of a carbinolamine (formed by hydration of 7) as important intermediates.Both geometric isomers can give biacetyl through a ring-opened intermediate that undergoes a carbon to oxygen migration of the aryl group.Only one geometric isomer can give 8, apparently by rapid decomposition of the alkoxide formed from the intermediate carbinolamine.The reaction of 6 is too complex to be able to fit the data quantitatively to a particular reaction mechanism, but qualitative considerations indicate that 8 can be formed from 6 by three different mechanisms that all seem to be competing under the reaction conditions.The relevance of these findings to related enzymic reactions is briefly considered.
Fraser, Mark S.,Hamilton, Gordon A.
p. 4203 - 4211
(1982)
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AZIRINYL AND DIAZIRINYL (CHLORIDE) ION PAIRS AS INTERMEDIATES
Both ab initio calculations and experimental observations support the intermediacy of diazirinyl or azirinyl cation-chloride anion pairs in transformations (1), (2), and (4).
Krogh-Jespersen, Karsten,Young, Claire M.,Moss, Robert A.,Wiostowski, Marek
p. 2339 - 2342
(1982)
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KINETICS AND MECHANISM OF THE OXIDATION OF SOME ALIPHATIC KETONES BY N-BROMOACETAMIDE IN ACIDIC MEDIA
Kinetics of the oxidation of methyl ethyl ketone (MEK) and diethyl ketone (DEK) by N-bromoacetamide (NBA) have been studied in perchloric acid media in the presence of mercuric acetate.A zero order dependence to NBA and a first-order dependence to both ketones and H(1+) have been observed.Acetamide, mercuric acetate and sodium perchlorate additions have negligible effect while addition of acetic acid has a positive effect on the reaction rate.A solvent isotope effect (K0D2O/k0H2O=2.1-2.4 and 2.2-2.5 for MEK and DEK, respectively) has been obsvered at 40 deg C.Kinetic investigations have revealed that the order of reactivity is MEK > DEK.The rates were determined at four different temperatures and the activation parameters were evaluated.The main product of the oxidation is the corresponding 1,2-diketone.A suitable mechanizm consistent with the above observations has been proposed.
Singh, Bharat,Saxena, B. B. L.,Samant, A. K.
p. 3321 - 3324
(1984)
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Avery,Cvetanovic
p. 3727
(1965)
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Kinetics and mechanism of the tropospheric reaction of 3-hydroxy-3-methyl- 2-butanone with Cl atoms
The relative rate coefficient for the gas-phase reaction of 3-hydroxy-3-methyl-2-butanone (3H3M2B) with Cl atoms was determined under atmospheric conditions (298 ± 2 K, 720 ± 2 Torr). The products of the reaction were identified and quantified. This work
Sleiman,El Dib,Ballesteros,Moreno,Albaladejo,Canosa,Chakir
p. 6163 - 6170
(2014)
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Cvetanovic
p. 775
(1956)
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Michaelian,Hoecker,Hammer
(1938)
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Reaction Kitenics in Acetyl Chemistry over a Wide Range of Temperature and Pressure
The molecular modulation spectrometer has been used to study the complex chemical kitenics involed in acetyl radical chemistry.This has involved direct monitoring of both acetyl and methyl radicals in the same experiment and over a variety of temperatures (263 /1019 molecule cm-3 = 2.7) conditions.These measurements have been complemented by a non-linear least-squares analysis of the experimental data and simple product studies.Rate data on four reactions and the absorption cross-section of the acetyl radical at 223 nm have been determined in this way.Unimolecular rate theory, based on Kassel integrals, has been applied to the pressure-dependent formation and decay of the radical to extract limiting values for the rate constants at T = 303 and 343 K.
Anastasi, Christopher,Maw, Paul R.
p. 2423 - 2434
(1982)
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Ho et al.
p. 1632,1633, 1634
(1975)
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Synthesis of 2,3-butanedione over TS-1, Ti-NCl, TiMCM-41, Ti-Beta, Fe-Si, Fe-Beta and VS-1 zeolites
The purpose of this work is the synthesis of 2,3-butanedione (diacetyl) by selective oxidation of 2-butanone (methyl ethyl ketone) in the presence of O2 and H2O2 30% as oxidants. All the tests were performed over several selective oxidation zeolite catalysts, synthesized and characterized in our laboratory.
Beltramone, Andrea,Gomez, Marcos,Pierella, Liliana,Anunziata, Oscar
p. 610 - 611
(2000)
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Rate coefficients for the reaction of the acetyl radical, CH3CO, with Cl2 between 253 and 384 K
Rate coefficients, k, for the gas-phase reaction CH3CO + Cl 2 → products (2) were measured between 253 and 384 K at 55-200 Torr (He). Rate coefficients were measured under pseudo-first-order conditions in CH3CO with CHsub
Gierczak,Rajakumar,Flad, Jonathan E.,Burkholder, James B.
p. 543 - 553
(2009)
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Synthesis of Dialkyl- and Alkylacylrhenium Complexes by Alkylation of Anionic Rhenium Complexes at the Metal Center. Mechanism of a Double Carbonylation Reaction That Proceeds via the Formation of Free Methyl Radicals in Solution
The site of alkylation of salts of acylrhenates such as Li(1+)(1-) (1) can be controlled by adjusting the hardness of the alkylating agent.Thus, treatment of 1 with the hard alkylating agent (CH3)3OPF6 gives predominantly the clssical Fischer carbene complex Cp(CO)2Re=C(OCH3)(CH3) (2), whereas reaction with the softer electrophile CH3I leads almost exclusively to the new metal-alkylated complex Cp(CO)2Re(CH3)(COCH3) (3).The structure of 3 has been determined by X-ray diffraction.The availability of this material, a relatively rare example of astable alkylacylmetal complex, has provided an opportunity to study the products and mechanisms of its carbon-carbon bond-forming decomposition reactions.Thermally, the alkyl acyl complex undergoes simple reductive elimination, leading (in the presence of a metal-scavenging ligand L) to a quantitative yield of acetone and CpRe(CO)2(L).Photochemically, a more complicated reaction takes place, especially under 20 atm of CO, where CpRe(CO)3 and 2,3-butanedione are formed.Strikingly, irradiation of Cp(CO)2Re(CH3)2 (9) under 20 atm of CO gives products identical with those formed from 3.Labeling experiments using (13)CO and mixtures of acetyl- and propionylrhenium complexes are inconsistent with a mechanism involving simple migratory CO insertion followed by reductive elimination.They are, however, consistent with metal-carbon bond homolysis leading to methyl and acetyl radicals, followed by carbonylation of the methyl radicals to give a second source of acetyl radicals; these reactive intermediates then dimerize to give 2,3-butanedione.Confirmation of this mechanism was obtained by trapping all the initially formed radicals withhalogen donors.BrCCl3, proved to be much more efficient than CCl4 for this purpose: irradiation of alkyl acyl complex 3 in the presence of BrCCl3 diverted the reaction completely from 2,3-butanedione production, giving instead CH3Br, CH3COBr, Cp(CO)2Re(CH3)Br, and Cp(CO)2Re(CH3CO)Br.
Goldberg, Karen I.,Bergman, Robert G.
p. 1285 - 1299
(1989)
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Johlin
p. 892
(1915)
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Arnett et al.
p. 2482,2483, 2485
(1962)
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Spence,Wild
(1937)
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OXIDATION OF ALIPHATIC KETONES BY BROMAMINE-B: A KINETIC STUDY
The kinetics of oxidation of propan-2-one, butan-2-one, pentan-2-one, pentan-3-one and 4-methyl pentan-2-one by sodium N-bromobenzenesulphonamide or bromamine-B (BAB) in perchloric acid medium was studied at 30 deg C.The rate shows a first order dependence each on and +> and is independent of .Variation of ionic strength of medium and addition of the reaction product benzenesulphonamide have no effect on the rate and the dielectric effect is positive.The proposed mechanism involves acid catalysed enolisation of ketone in the rate limiting step followed by a fast interaction with the oxidant.This is supported by the magnitude of inverse solvent isotope effect of 1.62 +/- 0.01 observed in D2O medium.Activation parameters Ea, ΔH*, ΔS*, ΔG* and log A have been calculated by studying the reaction at different temperatures (293-309 K).
Mahadevappa, D.S.,Mohan, K.,Ananda, S.
p. 4857 - 4866
(1986)
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Sakuraba,Matsushima
p. 911
(1972)
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Gandini,Hackett
p. 6195,6198 - 6204
(1977)
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Iron complexes with nitrogen bidentate ligands as green catalysts for alcohol oxidation
The iron(II) complexes [Fe(N-N)3](OTf)2 (N-N = 2,2′- bipyridine, 1,10-phenanthroline and substituted derivatives) were employed as catalyst precursors for the oxidation of primary and secondary alcohols, including glycerol. The single-crystal structure of [Fe(bipy)3](OTf)2 was determined by X-ray crystallography.The catalytic reactions were performed using either H2O2 or tert-butilhydroperoxide (TBHP) as oxidating agent, in mild experimental conditions: with all catalysts employed, secondary alcohols were oxidized to the corresponding ketones with up to 100% yields, whereas other substrates gave lower conversions. Indications on the nature of the catalytically active species, which is probably formed via dissociation of a nitrogen ligand from the iron center, were obtained from NMR and ESI-MS spectra.
Chàvez, Jennifer E.,Crotti, Corrado,Zangrando, Ennio,Farnetti, Erica
p. 189 - 195
(2016)
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Atmospheric Chemistry of Selected Hydroxycarbonyls
Using a relative rate method, rate constants have been measured at 296 ± 2 K for the gas-phase reactions of the OH radical with 1-hydroxy-2-butanone, 3-hydroxy-2-butanone, 1-hydroxy-3-butanone, 1-hydroxy-2-methyl-3-butanone, 3-hydroxy-3-methyl-2-butanone, and 4-hydroxy-3-hexanone, with rate constants (in units of 10-12 cm3 molecule-1 s-1) of 7.7 ± 1.7, 10.3 ± 2.2, 8.1 ± 1.8, 16.2 ± 3.4, 0.94 ± 0.37, and 15.1 ± 3.1, respectively, where the error limits include the estimated overall uncertainty in the rate constant for the reference compound. Rate constants were also measured for reactions with NO3 radicals and O3. Rate constants for the NO3 radical reactions (in units of 10-16 cm3 molecule-1 s-1) were 1-hydroxy-2-butanone, 3 were observed, and upper limits to the rate constants of -19 cm3 molecule-1 s-1 were derived for all six hydroxycarbonyls. The dominant tropospheric loss process for the hydroxycarbonyls studied here is calculated to be by reaction with the OH radical.
Aschmann, Sara M.,Arey, Janet,Atkinson, Roger
p. 3998 - 4003
(2000)
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Photoinduced generation of 2,3-butanedione from riboflavin
The volatile compound formation from riboflavin solution of a phosphate buffer (0.1 M, pH 6.5) under light for 15 h was studied by SPME-GC and SPME-GC/MS analysis. Only one major compound in the riboflavin solution was formed and increased as the light exposure time increased. The light-exposed riboflavin solution had a buttery odor. The compound of riboflavin solution under light was analyzed by gas chromatography and olfactometry. The major volatile compound eluted from the gas chromatograph had a buttery odor. The buttery odor compound was positively identified as 2,3-butanedione by a combination of gas chromatographic retention time, mass spectrum, and odor evaluation of authentic 2,3-butanedione. The addition of sodium azide, a singlet oxygen quencher, to riboflavin solution minimized the formation of the buttery odor compound. Singlet oxygen was involved in the formation of the buttery odor. The 2,3-butanedione was produced from the reaction between riboflavin and singlet oxygen. Singlet oxygen was formed from triplet oxygen by riboflavin photosensitization mechanism. This is the first reported oxidation reaction between riboflavin and singlet or triplet in food and biological systems.
Jung, Mun Yhung,Oh, Young Seok,Kim, Dae Keun,Kim, Hyun Jung,Min, David B.
p. 170 - 174
(2007)
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Nodzu,Goto
(1940)
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Chemiluminescent aldehyde and β-diketone reactions promoted by peroxynitrite
Peroxynitrite is shown here to promote the aerobic oxidation of isobutanal (IBAL) and 3-methyl-2,4-pentanedione (MP) in a pH 7.2 phosphate buffer into acetone plus formate and biacetyl plus acetate, respectively. These products are expected from dioxetane intermediates, whose thermolysis is known to be chemiluminescent (CL). Accordingly, the extent of total oxygen uptake by IBAL at different concentrations parallels the corresponding CL maximum intensities. The pH profile based on oxygen uptake data for the MP reaction matches the titration curve of peroxynitrous acid (pK(a) ~ 7), indicating that peroxynitrite anion is the oxidizing agent. Energy transfer studies with IBAL and the 9,10-dibromoanthracene-2-sulfonate ion, a triplet carbonyl detector, indicates that triplet acetone (τ = 19 μs) is the energy donor. It is postulated that IBAL- or MP-generated triplet carbonyls are produced by the thermolysis of dioxetane intermediates, which are formed by the cyclization of α-hydroperoxide intermediates produced by insertion of dioxygen into the IBAL or MP enolyl radicals, followed by their reduction. Accordingly, EPR spin-trapping studies with 3,5-dibromo-4- nitrosobenzenesulfonic acid (DBNBS) and 2-methyl-2-nitrosopropane (MNP) revealed the intermediacy of carbon-centered radicals, as expected for one- electron abstraction from the enol forms of IBAL or MP by peroxynitrite. The EPR data obtained with IBAL also reveal formation of the isopropyl radical produced by competitive nucleophilic addition of ONOO- to IBAL, followed by homolytic cleavage of this adduct and β-scission of the resulting Me2CHCH(O-)O·. Superstoichiometric formation of fragmentation products from IBAL or MP attests to the prevalence of an autoxidation chain reaction, here proposed to be initiated by one-electron abstraction by ONOO- from the substrate. This work reveals the potential role of peroxynitrite as a generator of electronically excited species that may contribute to deleterious and pathological processes associated with excessive nitric oxide and aldehyde production.
Knudsen, Fernanda S.,Penatti, Carlos A. A.,Royer, Leandro O.,Bidart, Karine A.,Christoff, Marcelo,Ouchi, Denise,Bechara, Etelvino J. H.
p. 317 - 326
(2000)
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Photo-oxidations of Acetoin and Biacetyl catalyzed by Tetrabutylammonium Decatungstate(4-) in Acetonitrile under Excess of Oxygen
Under an excess of oxygen, the photo-oxidation of acetoin catalysed by (NBu4)4(W10O32) and based on irradiation (λ > 300 nm) of the charge-transfer band in acetonitrile solution has been investigated.After irradiating for 30 h the products were biacetyl and acetic acid.The acetic acid was produced from both the acetoin and biacetyl.The rate constant for each path was determined by computer simulation.The production of biacetylis based on dehydrogenation of acetoin in conjunction with the redox cycle of (W10O32)4- attained by reaction with O2, whereas the production of acetic acid from biacetyl is based on the photoexcitation of biacetyl complexed with (W10O32)4- and subsequent reactions with O2 and water.
Nomiya, Kenji,Maeda, Katsunori,Miyazaki, Toshiaki,Miwa, Makoto
p. 961 - 962
(1987)
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Davis,Rogers,Thiel
p. 558
(1939)
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Sol-gel synthesis of ceria-zirconia-based high-entropy oxides as high-promotion catalysts for the synthesis of 1,2-diketones from aldehyde
Efficient Lewis-acid-catalyzed direct conversion of aldehydes to 1,2-diketones in the liquid phase was enabled by using newly designed and developed ceria–zirconia-based high-entropy oxides (HEOs) as the actual catalysts. The synergistic effect of various cations incorporated in the same oxide structure (framework) was partially responsible for the efficiency of multicationic materials compared to the corresponding single-cation oxide forms. Furthermore, a clear, linear relationship between the Lewis acidity and the catalytic activity of the HEOs was observed. Due to the developed strategy, exclusively diketone-selective, recyclable, versatile heterogeneous catalytic transformation of aldehydes can be realized under mild reaction conditions.
Dinjar, Kristijan,Djerdj, Igor,Koj?inovi?, Jelena,Kukovecz, ákos,Markovi?, Berislav,Mileti?, Aleksandar,Nagy, Sándor Balázs,Sapi, Andras,Stenzel, David,Széchenyi, Aleksandar,Szenti, Imre,Tang, Yushu,Tatar, Dalibor,Varga, Gábor,Ziegenheim, Szilveszter
(2021/10/20)

A study on the cataluminescence of propylene oxide on FeNi layered double hydroxides/graphene oxide
In this work, FeNi layered double hydroxides/graphene oxide (FeNi LDH/GO) was prepared, which exhibits excellent selective cataluminescent performance towards propylene oxide. The selectivity and sensitivity of the cataluminescence (CTL) reaction were investigated in detail. Moreover, the catalytic reaction mechanism, including the intermediate products and the conversion of reactants to products, was discussed based on both the experimental and computational results. Furthermore, the proposed FeNi LDH/GO based CTL sensor was successfully applied for the determination of propylene oxide residue in fumigated raisins, which indicates extensive application potential for rapid food safety evaluation.
Li, Ming,Hu, Yufei,Li, Gongke
p. 11823 - 11830
(2021/07/11)

Efficient production of adipic acid from 2-methoxycyclohexanone by aerobic oxidation with a phosphotungstic acid catalyst
Oxidative cleavage reaction of 2-methoxycyclohexanone (2-MCO) to adipic acid (AA) and methanol with O2 in water solvent was investigated. 2-MCO and AA are one of the lignin-based compounds produced via hydrogenation of guaiacol and an important monomer in industry, respectively. Various vanadium compounds and heteropolyacids were tested as homogeneous catalysts because vanadium compounds, especially phosphomolybdovanadic acids, have been known to be active in various oxidative cleavage reactions with O2. Simple vanadium-free phosphotungstic acid (H3PW12O40), which has not been regarded as an oxidation catalyst using O2 as the oxidant, showed good catalytic activity and excellent selectivity to AA. The carbon-based AA yield reached 74% (86% in molar basis) and this value was higher than those obtained with vanadium-based catalysts. A reuse test and 31P NMR confirmed that the H3PW12O40 catalyst was stable and reusable. Kinetic studies and the reaction test using a radical inhibitor suggested that the reaction mechanism is not auto-oxidation involving free radicals. Instead, the substrate was first activated by one-electron oxidation by H3PW12O40 catalyst and then reacted with O2.
Hatakeyama, Kosuke,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
p. 4962 - 4974
(2020/08/25)

METHOD FOR THE HYDRODEOXYGENATION OF OXYGENATED COMPOUNDS TO UNSATURATED PRODUCTS
The invention relates to methods of hydrodeoxygenation of oxygenated compounds into compounds with unsaturated carbon-carbon bonds, comprising the steps of: a) providing a reaction mixture comprising, an oxygenated compound containing one or more of a hydroxyl, keto or aldehyde group, an ionic liquid, a homogeneous metal catalyst, and carbon monoxide or a carbon monoxide releasing compound, b) reacting said reaction mixture under a H2 atmosphere at acidic conditions at a temperature between 180 and 250 °C and a pressure between 10 and 200 bar.
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Page/Page column 10

(2021/01/23)

Bioinspired oxidation of oximes to nitric oxide with dioxygen by a nonheme iron(II) complex
The ability of two iron(II) complexes, [(TpPh2)FeII(benzilate)] (1) and [(TpPh2)(FeII)2(NPP)3] (2) (TpPh2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate, NPP-H = α-isonitrosopropiophenone), of a monoanionic facial N3 ligand in the O2-dependent oxidation of oximes is reported. The mononuclear complex 1 reacts with dioxygen to decarboxylate the iron-coordinated benzilate. The oximate-bridged dinuclear complex (2), which contains a high-spin (TpPh2)FeII unit and a low-spin iron(II)–oximate unit, activates dioxygen at the high-spin iron(II) center. Both the complexes exhibit the oxidative transformation of oximes to the corresponding carbonyl compounds with the incorporation of one oxygen atom from dioxygen. In the oxidation process, the oxime units are converted to nitric oxide (NO) or nitroxyl (HNO). The iron(II)–benzilate complex (1) reacts with oximes to afford HNO, whereas the iron(II)–oximate complex (2) generates NO. The results described here suggest that the oxidative transformation of oximes to NO/HNO follows different pathways depending upon the nature of co-ligand/reductant.
Bhattacharya, Shrabanti,Lakshman, Triloke Ranjan,Sutradhar, Subhankar,Tiwari, Chandan Kumar,Paine, Tapan Kanti
p. 3 - 11
(2019/11/11)

Method of utilizing reactive distillation column to continuously prepare butanedione
The invention relates to a method of utilizing a reactive distillation column to continuously prepare butanedione. The preparation method comprises the steps: reacting acetoin with ferric oxide, dropwise adding hydrogen peroxide, adjusting a reflux ratio, supplementing the acetoin and the hydrogen peroxide and the like. According to the method disclosed by the invention, a reactive distillation mode is utilized to achieve continuous production of a 2,3-butanedione product, and the purity of the prepared 2,3-butanedione product can reach 99% or more. According to the method disclosed by the invention, the environment-friendly hydrogen peroxide is utilized as an oxidizing agent, so that the use amount of ferric chloride is greatly reduced; Fe of the ferric chloride can be reduced to be Fe when serving as the oxidizing agent to participate in oxidizing the acetoin, and the Fe is oxidized into Fe by the hydrogen peroxide again; thus, the service life of ferric chloride is prolonged, a recycling effect is achieved, and the yield of solid waste is greatly reduced. The method disclosed by the invention is an environment-friendly synthetic process route.
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Paragraph 0081-0164

(2019/01/24)

New insights for the valorisation of glycerol over MgO catalysts in the gas-phase
Aqueous glycerol solutions of up to 50 wt% were reacted over magnesium oxide catalysts at temperatures greater than 300 °C, the reactivity of which was compared to catalyst-free reactions. Under catalyst-free conditions, modest levels of dehydration to hydroxyacetone were observed at temperatures >400 °C in a steel reactor tube and >320 °C over silicon carbide. For reactions over MgO, the product distribution becomes more diverse, resulting in the formation of methanol, acetaldehyde, ethylene glycol, 1,2-propanediol and acetic acid. The methanol space-time-yield over MgO catalyst samples (0.5 g) was found to be highest at 400 °C (205 g h-1 kgcat-1) with a 50 wt% solution of glycerol, or with a glycerol concentration of 10 wt%; 255 g h-1 kgcat-1 over 0.1 g of catalyst. Despite the high glycerol conversion achieved, the MgO catalyst was found to be stable over 48 h, following a modest decrease in glycerol conversion during the initial 2 h of reaction. Post-reaction characterisation revealed that the level of coking at high glycerol conversions (>90%) was ≥120 mg gcat-1. The carbon mass balance determined by GC analysis for a typical reaction was 75% and so the carbon lost from catalyst coking only represents a modest quantity of the missing carbon; typically 10%. MgO was also found to promote the formation of high molecular weight products via condensation reactions, which were responsible for the remainder of the missing carbon; ca. 15%. Therefore, the total organic content of the post-reaction mixture and coke was calculated to be 94% of the starting solution. We conclude that the catalyst surface directs the formation of methanol, however, the results indicate that the reaction conditions are crucial to obtain optimum yields.
Smith, Louise R.,Smith, Paul J.,Mugford, Karl S.,Douthwaite, Mark,Dummer, Nicholas F.,Willock, David J.,Howard, Mark,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
p. 1464 - 1475
(2019/03/26)

Well-dispersed nickel nanoparticles on the external and internal surfaces of SBA-15 for hydrocracking of pyrolyzed α-cellulose
Catalysts comprising nickel supported on SBA-15 were prepared by wet impregnation and co-impregnation methods. Wet impregnation was performed by directly dispersing an Ni(NO3)2·6H2O aqueous solution into SBA-15, whereas in co-impregnation, ethylene glycol (EG) was added to nickel nitrate aqueous solution prior to dispersion into SBA-15. After drying and calcination, NiO/SBA-15w and NiO/SBA-15c were produced. Later, after the reduction process, Ni/SBA-15w and Ni/SBA-15c were obtained. The prepared catalysts were evaluated for the hydrocracking of pyrolyzed α-cellulose. The TEM images revealed that the catalysts prepared by wet impregnation showed inhomogeneous distribution of nickel loading, whereas catalysts prepared by co-impregnation using EG exhibited homogeneous distribution and formed no nickel aggregates. During hydrocracking of pyrolyzed α-cellulose, Ni/SBA-15c with total acidity, nickel loading, particle size, and specific surface area of 7.27 m mol g?1, 5.20 wt%, 3.17 nm, and 310.0 m2 g?1, respectively, exhibited the best catalytic performance compared to other prepared catalysts with 67.35 wt% conversion of liquid product with maximum selectivity in producing 13.09 wt% of 3-methyl-pentane. Moreover, Ni/SBA-15w with total acidity, nickel loading, particle size, and specific surface area of 10.87 m mol g?1, 8.15 wt%, 7.01 nm, and 628.0 m2 g?1, respectively, produced 69.89 wt% liquid product without hydrocarbons. Study of selectivity towards the formation of liquid hydrocarbons was carried out via double step hydrocracking using Ni/SBA-15w, and 18.55 wt% of n-hexane was produced in the liquid product.
Trisunaryanti, Wega,Suarsih, Endah,Triyono,Falah, Iip Izul
p. 1230 - 1237
(2019/01/23)

Microwave-assisted green oxidation of alcohols with hydrogen peroxide catalyzed by iron complexes with nitrogen ligands
Oxidation of primary and secondary alcohols, including two diols and glycerol, with H2O2 was catalyzed by the iron(II) complexes [FeL3](OTf)2 (L = 2,2′-bipyridine, 2,2′-bipyrimidine, 1,10-phenanthroline and substituted derivatives) and [FeL2](OTf)2 (L = bis(2-pyridinylmethyl)amine, 2,6-di(2-pyridyl)pyridine). The reactions were performed in acetonitrile, water or mixed solvent (typically water/acetonitrile 4:1) in a microwawe reactor at low power. Effect of addition of a cocatalyst, which in some cases improved the yields of the catalytic reaction, was investigated by means of NMR and UV–Visible techniques.
Cozzi, Irene Sofia,Crotti, Corrado,Farnetti, Erica
p. 38 - 47
(2018/10/21)

Green synthesizing method for 2,3-butanedione
The invention discloses a green synthesizing method for 2,3-butanedione. The green synthesizing method comprises the following process steps: taking acetaldehyde (I) as a raw material and thiazolium salt as a catalyst, regulating the PH value of reaction liquid to be 9-10 by sodium bicarbonate, heating in a pressure reaction kettle to carry out condensation reaction, if the pressure of the reaction kettle is reduced to 0Mpa after reacting for 3-4 hours, showing that reaction is finished basically, and cooling and distilling under reduced pressure to obtain acetoin (II); and adding water and a cocatalyst in the prepared acetoin (II), keeping low temperature, feeding ozone to carry out oxidizing reaction, tracking a reaction process by using a gas chromatography, removing a peroxide value after reaction is finished, carrying out distilling and separating under reduced pressure to obtain the 2,3-butanedione (III). The invention aims to overcome shortcomings in the prior art. The green synthesizing method for the 2,3 butanedione is simple in process and is pollution-free.
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Paragraph 0016-0018

(2017/09/01)

Electrochemistry for the Generation of Renewable Chemicals: One-Pot Electrochemical Deoxygenation of Xylose to Δ-Valerolactone
In this study, the electrochemical conversion of xylose to δ-valerolactone via carbonyl intermediates is demonstrated. The conversion was achieved in aqueous media and at ambient conditions. This study also demonstrates that the feedstock for production of renewable chemicals and biofuels through electrochemistry can be extended to primary carbohydrate molecules. This is the first report on a one-pot electrochemical deoxygenation of xylose to δ-valerolactone.
James, Olusola O.,Sauter, Waldemer,Schr?der, Uwe
p. 2015 - 2022
(2017/05/16)

Hydrogen-Free Gas-Phase Deoxydehydration of 2,3-Butanediol to Butene on Silica-Supported Vanadium Catalysts
The gas-phase deoxydehydration of 2,3-butanediol to butene was investigated in a plug flow reactor over SiO2-supported vanadium oxide, γ-alumina, P/ZSM-5, and MgO catalysts with acid/base sites of varying strengths. 5 wt % vanadium on SiO2 (i.e., 5V/SiO2) showed the best performance with 100 % conversion and up to 45.2 % butene selectivity. The combination of weak acid sites and polymeric VOx surface species provided the 5V/SiO2 catalyst with bifunctional capabilities to achieve both dehydration and transfer hydrogenation, which allowed it to catalyze the deoxydehydration of 2,3-butanediol to butene even in the absence of H2. As 2,3-butanediol is a common yet underutilized biomass product, this reaction may provide a viable route for a biomass-to-chemicals application for 2,3-butanediol.
Kwok, Kelvin Mingyao,Choong, Catherine Kai Shin,Ong, Daniel Sze Wei,Ng, Joy Chun Qi,Gwie, Chuandayani Gunawan,Chen, Luwei,Borgna, Armando
p. 2443 - 2447
(2017/07/12)

Insertion of an Isolable Dialkylstannylene into C-Cl Bonds of Acyl Chlorides Giving Acyl(chloro)stannanes
The reactions of isolable dialkylstannylene 1 with 1-adamantanoyl, 2,2-dimethylpropanoyl, benzoyl, and substituted benzoyl chlorides afford the corresponding acyl(chloro)stannanes in good yields. Similar reactions with more reactive acetyl and propanoyl c
Lu, Qiong,Yan, Chenting,Xiao, Xu-Qiong,Li, Zhifang,Wei, Ningka,Lai, Guoqiao,Kira, Mitsuo
p. 3633 - 3637
(2017/10/03)

Dendrimer-like core cross-linked micelle stabilized ultra-small gold nanoclusters as a robust catalyst for aerobic oxidation of α-hydroxy ketones in water
As one of the most general and promising stabilizers, dendrimers have been widely used to prepare ultra-small gold nanoclusters. However, the complex synthesis of dendrimers hinders the further application of protected nanoclusters. Here we report a facile strategy to prepare an alternative material via core cross-linking of self-assembled micelles. The resulting dendrimer-like core cross-linked micelles (DCCMs) retain the main characteristics of dendrimers and avoid complex chemical synthesis. As expected, the DCCMs could easily encapsulate gold nanoparticles within their cores. The ultra-small clusters of Au5 were prepared without the participation of external reductants. Importantly, the DCCM stabilized noble gold clusters furnish excellent catalytic activity and perfect reusability for aerobic oxidation of α-hydroxy ketones in water. Only in open air the oxidation could be repeated up to 48 times with negligible turn-over frequency change. The total turnover number (TON) of the reaction reached unexpectedly >48 000, the highest TON for metal catalysed oxidation of hydroxy ketones so far. The further mechanism study hints that the carboxylic group of substrates might be involved in the catalytic process. The simple catalyst preparation, the environmentally benign reaction conditions, and the excellent catalytic performance and durability make the novel DCCM protected gold nanocluster a green catalyst.
Yu, Yangyang,Lin, Chenlu,Li, Bing,Zhao, Pengxiang,Zhang, Shiyong
p. 3647 - 3655
(2016/07/06)

Zeolite-supported iron catalysts for allyl alcohol synthesis from glycerol
Under most reaction conditions studied, acrolein is reported as the primary product in the conversion of glycerol over zeolites. In such processes, acrolein forms at relatively high yields, with negligible allyl alcohol selectivity. In this contribution, we report the development of ZSM5-supported iron catalysts, modified by rubidium deposition, as stable materials for production of allyl alcohol from glycerol. Our results demonstrate a reduced rate of formation of acrolein over modified catalysts. Both unmodified and modified catalysts were analysed by inductively coupled plasma optical emission spectrometry, nitrogen adsorption, scanning electron microscope, X-ray diffraction, ammonia temperature programmed desorption, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. These techniques revealed that differences in product distribution and catalyst performance are due to the combined effects of iron loading, catalyst acidity and changes in the porosity of the catalyst.
Sánchez,Dlugogorski,Kennedy,Stockenhuber
p. 130 - 142
(2015/11/24)

1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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(2015/03/03)

Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
-
(2015/03/03)

Efficient green methanol synthesis from glycerol
The production of biodiesel from the transesterification of plant-derived triglycerides with methanol has been commercialized extensively. Impure glycerol is obtained as a by-product at roughly one-tenth the mass of the biodiesel. Utilization of this crude glycerol is important in improving the viability of the overall process. Here we show that crude glycerol can be reacted with water over very simple basic or redox oxide catalysts to produce methanol in high yields, together with other useful chemicals, in a one-step low-pressure process. Our discovery opens up the possibility of recycling the crude glycerol produced during biodiesel manufacture. Furthermore, we show that molecules containing at least two hydroxyl groups can be converted into methanol, which demonstrates some aspects of the generality of this new chemistry.
Haider, Muhammad H.,Dummer, Nicholas F.,Knight, David W.,Jenkins, Robert L.,Howard, Mark,Moulijn, Jacob,Taylor, Stuart H.,Hutchings, Graham J.
p. 1028 - 1032
(2015/11/28)

Gas-phase reaction of two unsaturated ketones with atomic Cl and O3: Kinetics and products
The rate constants and products for the reactions of atomic Cl and O3 molecule with 3-methyl-3-buten-2-one (MBO332) and 3-methyl-3-penten-2-one (MPO332) were determined in a 100 L Teflon chamber at 293 ± 1 K and atmospheric pressure. For MBO332 and MPO332, the rate constants measured with atomic Cl were (2.38 ± 0.26) × 10-10 and (3.00 ± 0.34) × 10-10 cm3 molecule-1 s-1 using the relative rate method. Using the absolute rate method, the rate constants with O3 measured were (1.18 ± 0.21) × 10-17 and (4.07 ± 0.45) × 10-17 cm3 molecule-1 s-1. The products of these reactions were investigated by the proton-transfer-reaction mass spectrum (PTR-MS). The results indicated that the major products observed in the atomic Cl reaction were formaldehyde together with chloroacetone for MBO332, and acetaldehyde and CH3C(O)C(O)Cl for MPO332. For O3 reactions, butanedione and formaldehyde were the main products of MBO332, while butanedione and acetaldehyde were the main products of MPO332. Possible reaction mechanisms were proposed and discussed and the atmospheric implications of these reactions were also discussed.
Wang, Jing,Zhou, Li,Wang, Weigang,Ge, Maofa
p. 12000 - 12012
(2015/05/26)

N-Heterocyclic carbene-catalyzed double acylation of enones with benzils
Thiazolium carbene-catalyzed reaction of aromatic 1,2-diketones with enones in aprotic solvents gave double acylation products in good yields, whereas hydroacylation products formed by Stetter reaction were not detected at all. These results suggested the generation of aroyloxyenamine species from the 1,2-diketones instead of hydroxyenamines (Breslow intermediates). This journal is
Takaki, Ken,Ohno, Akira,Hino, Makoto,Shitaoka, Takashi,Komeyama, Kimihiro,Yoshida, Hiroto
supporting information
p. 12285 - 12288
(2014/12/11)

Synthesis of ferrocene derivatives with planar chirality via palladium-catalyzed enantioselective C-H bond activation
The first catalytic and enantioselective C-H direct acylation of ferrocene derivatives has been developed. A series of 2-acyl-1-dimethylaminomethylferrocenes with planar chirality were provided under highly efficient and concise one-pot conditions with up to 85% yield and 98% ee. The products obtained could be easily converted to various chiral ligands via diverse transformations.
Pi, Chao,Cui, Xiuling,Liu, Xiuyan,Guo, Mengxing,Zhang, Hanyu,Wu, Yangjie
supporting information
p. 5164 - 5167
(2014/12/11)

Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
p. 6055 - 6058
(2014/12/10)

Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
p. 6055 - 6058
(2015/03/30)

Products of the OH radical-initiated reactions of furan, 2- and 3-methylfuran, and 2,3- and 2,5-dimethylfuran in the presence of NO
Products of the gas-phase reactions of OH radicals with furan, furan-d 4, 2- and 3-methylfuran, and 2,3- and 2,5-dimethylfuran have been investigated in the presence of NO using direct air sampling atmospheric pressure ionization tandem mass spectrometry (API-MS and API-MS/MS), and gas chromatography with flame ionization and mass spectrometric detectors (GC-FID and GC-MS) to analyze samples collected onto annular denuders coated with XAD solid adsorbent and further coated with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine for derivatization of carbonyl-containing compounds to their oximes. The products observed were unsaturated 1,4-dicarbonyls, unsaturated carbonyl-acids and/or hydroxy-furanones, and from 2,5-dimethylfuran, an unsaturated carbonyl-ester. Quantification of the unsaturated 1,4-dicarbonyls was carried out by GC-FID using 2,5-hexanedione as an internal standard, and the measured molar formation yields were: HC(O)CH=CHCHO (dominantly the E-isomer) from OH + furan, 75 ± 5%; CH3C(O)CH=CHCHO (dominantly the E-isomer) from OH + 2-methylfuran, 31 ± 5%; HC(O)C(CH3)=CHCHO (a E-/Z-mixture) from OH + 3-methylfuran, 38 ± 2%; and CH 3C(O)C(CH3)=CHCHO from OH + 2,3-dimethylfuran, 8 ± 2%. In addition, a formation yield of 3-hexene-2,5-dione from OH + 2,5-dimethylfuran of 27% was obtained from a single experiment, in good agreement with a previous value of 24 ± 3% from GC-FID analyses of samples collected onto Tenax solid adsorbent without derivatization.
Aschmann, Sara M.,Nishino, Noriko,Arey, Janet,Atkinson, Roger
p. 457 - 466
(2014/02/14)

The effect of PO4 to Nb2O5 catalyst on the dehydration of glycerol
The liquid-phase dehydration of glycerol to acrolein over PO 4/Nb2O5 catalysts was performed to investigate the effect of various amounts of PO4 supported and the regeneration of used catalysts on catalytic perf
Lee, Young Yi,Lee, Kyu Am,Park, Nam Cook,Kim, Young Chul
p. 114 - 118
(2014/06/09)

YbCl3-catalyzed one-pot synthesis of dihydropyrazines, piperazines, and pyrazines
A simple and efficient synthetic approach to dihydropyrazines via YbCl 3-catalyzed reaction of α-hydroxyketones with diamines under mild conditions was developed. The corresponding 2,3-subsitituted piperazines and pyrazines were obtained through tandem conversion of dihydropyrazines with good yields.
Fan, Liyan,Chen, Wen,Qian, Changtao
supporting information
p. 231 - 234
(2013/02/23)

Hypervalent iodine/TEMPO-mediated oxidation in flow systems: A fast and efficient protocol for alcohol oxidation
Hypervalent iodine(III)/TEMPO-mediated oxidation of various aliphatic, aromatic and allylic alcohols to their corresponding carbonyl compounds was successfully achieved by using microreactor technology. This method can be used as an alternative for the oxidation of various alcohols achieving excellent yields and selectivities in significantly shortened reaction times.
Ambreen, Nida,Kumar, Ravi,Wirth, Thomas
p. 1437 - 1442
(2013/08/23)

Reactivity of thermally treated α-dicarbonyl compounds
The degradation reaction of thermally treated 3-deoxy-d-erythro-hexos-2- ulose and methylglyoxal, both key intermediates in Maillard chemistry, was investigated. Different analytical strategies were accomplished to cover the broad range of formed products and their different chemical behavior. These involved HPLC-DAD and accordingly LC/MS analysis of the quinoxaline derivates, GC/MS analysis of the acetylated quinoxalines, and GC-FID analysis of the decyl ester of acetic acid. As a main degradation product of 3-deoxy-d-erythro-hexos- 2-ulose, 5-(hydroxymethyl)furfural could be identified. At alkaline pH values, 3-deoxy-d-erythro-hexos-2-ulose generated various acids but no colored products. In contrast, thermal treatment of methylglyoxal yielded high molecular weight, brownish products. A dimer of methylglyoxal, first precursor for aldol-based polymerization of methylglyoxal, could be clearly identified by GC/MS.
Pfeifer, Yvonne V.,Haase, Paul T.,Kroh, Lothar W.
p. 3090 - 3096
(2013/08/25)

Rate Constants for the Reactions of Oh Radicals with 1,2,4,5- Tetramethylbenzene, Pentamethylbenzene, 2,4,5-Trimethylbenzaldehyde, 2,4,5-Trimethylphenol, and 3-Methyl-3-Hexene-2,5-Dione and Products of OH + 1,2,4,5-tetramethylbenzene
Using a relative rate method, rate constants have been measured for the reactions of OH radicals with 1,2,4,5-tetramethylbenzene, pentamethylbenzene, 2,4,5-trimethylbenzaldehyde, 2,4,5-trimethylphenol and 3-methyl-3-hexene-2,5- dione at 298 ± 2 K and atmospheric pressure of air. The rate constants obtained (in units of 10-11 cm3 molecule-1 s-1) were: 1,2,4,5-tetramethylbenzene, 5.55 ± 0.34; pentamethylbenzene, 10.3 ± 0.8; 2,4,5-trimethylbenzaldehyde, 4.27 ± 0.39; 2,4,5-trimethylphenol, 9.75 ± 0.98; and 3-methyl-3-hexene-2,5-dione, 9.4 ± 1.1. The following first-generation products were identified from the OH + 1,2,4,5-tetramethylbenzene reaction in the presence of NO: biacetyl, methylglyoxal, 3-methyl-3-hexene-2,5-dione, and 2,4,5-trimethylbenzaldehyde. The measured molar formation yields for 3-methyl-3-hexene-2,5-dione and 2,4,5-trimethylbenzaldehyde were 45 ± 9% and 3.3 ± 0.7%, with that for 3-methyl-3-hexene-2,5-dione being extrapolated to low NO2 concentrations where the OH-1,2,4,5- tetramethylbenzene adducts react only with O2. Biacetyl appeared to be formed as both a first- and second-generation product, and a first-generation formation yield of 9 ± 3% was derived. The relative formation yield of methylglyoxal was ～0.8 of that for 3-methyl-3-hexene-2,5-dione, indicating that methylglyoxal and 3-methyl-3-hexene-2,5-dione are coproducts. H-atom abstraction from OH + 1,2,4,5-tetramethylbenzene is estimated to account for 3.7 ± 0.8% of the overall OH radical reaction. On the basis of the current understanding of the mechanism of the OH-aromatic adduct + O2 reaction, the observed formation of biacetyl indicates that some ipso addition of OH occurs for OH + 1,2,4,5-tetramethylbenzene.
Aschmann, Sara M.,Arey, Janet,Atkinson, Roger
p. 2556 - 2568
(2013/06/26)

Photochemical reactions of acyl iodides with aryl halides
Photochemical reactions of acyl iodides RC(O)I (R = Me, Ph) with aryl halides, fluoro-, chloro-, and bromobenzenes, 1,4-dibromobenzene, 2- and 3-bromotoluenes, and 4-bromo-1,2-dimethylbenzene, were studied. Acetyl iodide reacted with chloro- and bromobenzenes and 1,4-dibromobenzene according to the exchange pattern to give iodobenzene and 1,4-diiodobenzene, respectively. No halogen exchange was observed in the reactions of acetyl iodide with fluorobenzene and hexafluorobenzene. Benzoyl iodide failed to react with chloro- and brombenzene under UV irradiation but underwent polycondensation with formation of black nonfusible oligomers which were found to possess paramagnetic and semiconducting properties. Ultraviolet irradiation of a mixture of MeCOI with 2- or 3-bromotoluene, as well as with 4-bromo-1,2-dimethylbenzene, also led to the formation of polymeric products as a result of polycondensation of aryl iodides formed initially via replacement of bromine by iodine. Irradiation of benzoyl iodide in 2- or 3-bromotoluene involved recombination of benzoyl radicals to give benzil as the only product.
Voronkov,Vlasova,Belousova,Vlasov,Vakul'Skaya,Prozorova,Khutsishvili
p. 17 - 21
(2013/03/29)

Catalytic dehydration of d-xylose to 2-furfuraldehyde in the presence of Zr-(W,Al) mixed oxides. Tracing by-products using two-dimensional gas chromatography-time-of-flight mass spectrometry
Zirconium-tungsten mixed oxides (ZrW) are effective catalysts in the aqueous-phase dehydration of d-xylose to 2-furfuraldehyde (Fur), at 170 °C. The texture and acid properties of ZrW materials were modified to enhance Fur yields. The catalysts prepared by co-condensation without a templating agent (ZrW(X), X = NO3, Cl; X is related to the type of zirconium precursor) possess relatively low specific surface area and amounts of accessible acid sites, leading to a modest Fur yield of ca. 35% at 99% conversion. The use of a templating agent in the preparation of mesoporous ZrW (ZrW-MP) increased considerably the specific surface area and the amount of accessible acid sites, which resulted in enhanced Fur yields (42%) reached at comparable conversions. Further improvements in Fur yields at high conversions were accomplished by introducing aluminium in the catalyst preparation procedure to give ZrAlW-MP (51% yield at 98% conversion). Fairly good catalytic results were also obtained in the case of the ZrAlW-MP catalyst, using solely water as solvent (46% yield at 93% conversion). A study of the identification of the reaction by-products by two-dimensional gas chromatography (GC × GC) combined with time-of-flight mass spectrometry (ToFMS) was carried out.
Antunes, Margarida M.,Lima, Sérgio,Fernandes, Auguste,Candeias, Joana,Pillinger, Martyn,Rocha, Sílvia M.,Ribeiro, Maria Filipa,Valente, Anabela A.
p. 127 - 135
(2013/01/15)

V- or Mo-modified niobium catalysts for glycerin conversion reactions in the presence of H2O2
In the present work, amorphous niobium oxides with 5% (w/w) vanadium or molybdenum isomorphically substituted into the material structure were synthesized. The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results show that vanadium and molybdenum were incorporated into the niobium oxide structure with concomitant changes in the morphologic and catalytic properties. Catalytic studies on the conversion of residual glycerin generated during biodiesel production in the presence of H2O2 showed enhanced efficiency of ether formation with the vanadium-containing material. The NbV/ethanol/glycerin/250 °C system was found to convert 80% of glycerin. Experiment-planning studies in conjunction with the analysis of the surface response via gas chromatography-mass spectrometry (GC-MS) aided in the determination of the optimal conditions. The catalytic tests monitored by GC-MS showed the formation a mixture of ethers obtained by the condensation of glycerol. Furthermore, it was observed that the modification of the catalyst directs the formation of larger molecules such as ketone mainly in the catalyst containing vanadium.
Souza, Juber P.,Melo, Thaís,De Oliveira, Marcone A.L.,Paniago, Roberto M.,De Souza, Patterson P.,Oliveira, Luiz C.A.
p. 153 - 160
(2012/11/13)

Direct carbo-acylation reactions of 2-arylpyridines with α-diketones via Pd-catalyzed C-H activation and selective C(sp2)-C(sp2) cleavage
An efficient carbo-acylation reaction of 2-arylpyridines with α-diketones via Pd-catalyzed C-H bond activation and C-C bond cleavage in the presence of TBHP was developed that generated aryl ketones in good yields. The highly selective formation of aryl ketones was observed when 2-arylpyridines reacted with aromatic/aliphatic α-diketones.
Zhou, Wei,Li, Hongji,Wang, Lei
supporting information
p. 4594 - 4597
(2012/10/29)

MAGNETIC RESONANCE IMAGING AND/OR SPECTROSCOPY CONTRAST AGENTS AND METHODS OF USE THEREOF
The presently disclosed subject matter demonstrates that a spin state which has zero magnetic resonance signal, but an extremely long lifetime, can be used to store magnetization, which can then be recovered into an observable transition. Coupled with hyper-polarization techniques, this permits the preparation of a wide range of contrast agent molecules for use in magnetic resonance imaging (MRI) techniques that have long effective relaxation time.
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(2011/08/22)

Photochemical reactions of acyl iodides with haloarenes
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Vlasova,Belousova,Vlasov,Vakul'Skaya,Khutsishvili,Voronkov
scheme or table
p. 164 - 166
(2011/12/15)

Oxidative decarboxylation of levulinic acid by silver(I)/persulfate
The oxidative decarboxylation of levulinic acid (LA) by silver(I)/persulfate [Ag(I)/S2O82-] has been investigated in this paper. The effects of buffer solution, initial pH value, time and temperature and dosages of Ag(I)/S2O8 2- on the decarboxylation of LA were examined in batch experiments and a reaction scheme was proposed on basis of the reaction process. The experimental results showed that a solution of NaOH-KH2PO4 was comparatively suitable for the LA decarboxylation reaction by silver(I)/persulfate. Under optimum conditions (temperature 160 °C, pH 5.0, and time 0.5 h), the rate of LA conversion in NaOH-KH2PO4 solutions with an initial concentration of 0.01 mol LA reached 70.2%, 2-butanone (methyl ethyl ketone) was the single product in the gas phase and the resulted molar yield reached 44.2%.
Gong, Yan,Lin, Lu
scheme or table
p. 2714 - 2725
(2011/05/08)

Alcohol oxidation catalysed by Ru(VI) in the presence of alkaline hexacyanoferrate(III)
The oxidation of sodium lactate, 2-methyl-2,4-pentanediol, 2,4-butanediol, 2-butanol and 2-propanol upon treatment with alkaline hexacyanoferrate(III) using a Ru(VI) catalyst is highly effective for the oxidation of alcohols by Fe(CN)63-. The reaction mechanism proposed involves the oxidation of the alcohol by the catalyst, a process that occurs through the formation of a substrate-catalyst complex. The decomposition of this complex yields Ru(IV) and a carbocation (owing to a hydride transfer from the α-C-H bond of the alcohol to the oxoligand of ruthenium). The role of the co-oxidant, hexacyanoferrate(III), is to regenerate the catalyst. In the oxidation reactions, the rate constants for complex decomposition and catalyst regeneration have been determined and a comparative study of the structure versus reactivity has been carried out. Copyright
Poblete, Francisco J.,Corrochano, Pablo
experimental part
p. 1088 - 1092
(2011/07/06)

Expected and unexpected photochemical reactions of acyl iodides
Photolysis of acyl iodides RCOI (R = Me, Me2CH, Ph) under UV irradiation in toluene environment for 20-55 h proved to be a simple and efficient method of preparation of symmetrical α-diketones RCOCOR. In contrast, the photolysis under the same
Voronkov,Vlasova,Vlasov,Belousova,Grigor'Eva,Albanov,Myachina,Vakul'Skaya
experimental part
p. 1616 - 1620
(2010/04/27)

Pyridine-catalyzed stereoselective addition of acyclic 1,2-diones to acetylenic esters: Synthetic and theoretical studies of an unprecedented rearrangement
A systematic study of the addition of various 1,2-acyclic diones to activated acetylenic esters catalyzed by pyridine under mild conditions is described. This reaction provides a new protocol for the stereoselective synthesis of 1,2-diaroyl maleates. The exclusive formation of the cis isomer is especially noteworthy. This reaction occurs through the initial generation of a pyridine-dimethyl acetylene dicarboxylate zwitterion and its addition to the dione followed by an unprecedented benzoyl migration. Pyridine and substituted pyridines, such as 4-dimethylaminopyridine (DMAP) and 3-methoxypyridine, are the best catalysts and anhydrous 1,2-dimethoxyethane is found to be the solvent of choice. Structural, electronic, energetic and mechanistic details of the reaction are also revealed by density functional theory calculations, which strongly support the exclusive formation of the cis isomer of the 1,2-diaroyl maleates.
Pillai, Abhilash N.,Suresh, Cherumuttathu H.,Nair, Vijay
supporting information; experimental part
p. 5851 - 5860
(2009/06/05)

Synthesis of symmetric α-diketones
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Voronkov,Belousova,Vlasov,Vlasova
body text
p. 929 - 930
(2009/05/31)

A PREPARATION METHOD OF BUTADIONE BY GAS-PHASE OXIDATIING 3-HYDROXY-BUTANONE
A novel preparation method for butadione by gas-phase oxidation of 3-hydroxy-butanone is established. The fermentation broth or water solution of 3-hydroxy-butanone is heated to vaporize. The resulting vapour is mixed with air under the molar ratio of oxygen to 3-hydroxy-butanone of 0.5 - 2.5 and then introduced continuously into a fixed bed reactor with activated carbon at the space velocity of 500 h-1 ~ 2500 h-1. The reaction temperature is 110°C ~ 190°C. Butadione is collected by the conventional condensation method at the outlet of the fixed bed reactor. The yield of butadione produced by the present method is 82%. The purity can reach above 98% after rectification. The present method has many advantages such as lower cost, easier operation and controlling, lower reaction temperature, higher reliability, and no substantial pollution.
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Page/Page column 45

(2008/06/13)

Products, kinetic regularities, and mechanism of thermal decomposition of ethyl(methyl)dioxirane
The products and kinetic regularities of thermal decomposition of ethyl(methyl)dioxirane (EMD) were studied. The consumption of EMD occurs via four parallel pathways: two isomerizations to ethyl acetate and methyl propionate, solvent oxidation via insertion of the oxygen atom into the C-H bond of a solvent molecule (butanone), and hydrogen atom abstraction from the solvent by dioxirane with radical escape from the cage. The contribution of the latter route to the oxidation of butan-2-one at 35°C is 43%. Alkyl radicals initiate EMD decomposition in an inert atmosphere. The activation parameters of EMD isomerization to esters and the reaction of EMD with butanone were determined. The isomerization of EMD was studied by the DFT method. The geometric parameters were optimized at the UB3LYP level using the 6-31G**and/or 6-311+G**basis sets. The calculated energies were corrected taking into account zero-point vibrations. The theoretical results are in good agreement with experimental data. The mechanism of EMD thermolysis is considered.
Grabovskiy,Markov,Ryzhkov,Kabal'nova
p. 1780 - 1787
(2008/02/10)

Photo-CIDNP studies of hydroxy ketones and higher-molecular-weight systems
In situ NMR spectroscopy can be applied to investigate chemical reactions during which free radicals occur as intermediates. In chemical systems of low molecular weight, nuclear-spin polarization results from the spin selectivity of free-radical reactions, because a pair of radicals has to obey the exclusion principle according to Pauli; therefore, this system reacts in a spin-selective manner when forming a chemical single bond. As a consequence, strong transient absorption and emission lines occur in the NMR spectra acquired during free-radical reactions. This phenomenon is known as 'chemically induced dynamic nuclear polarization' (CIDNP). However, long correlation times associated with short proton spin-lattice relaxation times T1 render it difficult to observe CIDNP in macromolecules. Therefore, in these and in many other cases, it can be attractive to utilize the simultaneously occurring heteronuclear polarization or to selectively transfer the 1H polarization to heteronuclei, since their T1 times can be substantially shorter than those of protons. In this paper, we present examples of how CIDNP can be observed both in low-molecular-weight systems as well as in systems exhibiting a rather macromolecular character. Also, CIDNP can assist in obtaining useful information about macromolecular systems that normally is very difficult to obtain otherwise. Since CIDNP is primarily a qualitative method by which free-radical intermediates may be identified, we have developed a procedure allowing the quantitative determination of the magnetic properties of the intermediate free radicals. This process is especially useful for very short-lived radicals, which are frequently elusive to ESR spectroscopy conducted in solution. In particular, g values of a variety of radical ions have been determined in this fashion by CIDNP-NMR spectroscopy. The data thus obtained provide an alternative to ESR and, hence, complement this traditional method (manuscript in preparation).
Bargon, Joachim,Kuhn, Lars T.
p. 2522 - 2532
(2007/10/03)

Acyl iodides in organic synthesis: VII. Reactions with trialkyl(alkynyl) silanes, -germanes, and -stannanes
Reactions of acyl iodides R1COI (R1 = Me, Ph) with trialkyl(alkynyl)silanes, -germanes, and stannanes (R2C≡ CMR33; M = Si, Ge, Sn) were studied. Acyl iodides reacted with the germanium and tin derivatives with cleavage of the M-Csp bond and formation of the corresponding trialkyl(iodo)germanes and -stannanes R33MI (M = Ge, Sn) and alkynyl ketones R 1C(O)C≡CR2 and R1C(O)C≡CC(O)R 1. By contrast, the reaction of acetyl iodide with ethynyl(trimethyl)silane gave only a small amount of 1,2-diiodovinyl(trimethyl) silane as a result of iodine addition at the triple bond. Bis(trimethylsilyl) ethyne failed to react with acetyl iodide. Pleiades Publishing, Inc., 2006.
Voronkov,Trukhina,Vlasova,Mirskov,Yarosh
p. 23 - 26
(2007/10/03)

N,N-Dibromobenzenesulfonamide as a reagent for oxidative cleavage of oximes to their parent carbonyl compounds under non-aqueous and aprotic conditions
Deprotection of different oximes to their parent aldehydes and ketones in high yields has been carried out by using N,N-dibromobenzenesulfonamide(dibromoamine-b) under mild conditions.
Tajbakhsh, Mahmood,Khazaei, Ardeshir,Shabani-Mahalli, Majid,Ghorbani-Vaghei, Ramin
p. 141 - 142
(2007/10/03)