- The thermal stability and safety of 2, 5-dimethylfuran (DMF) oxidation
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DMF is renewable energy obtained from glucose, its thermal stability and safety need to be investigated. Accelerated rate calorimeter (ARC) is widely used to evaluate the risk of hazardous materials. In this paper, the thermal stability and safety of DMF oxidation were investigated using an ARC. DMF does not react even when the temperature reaches 452 K under nitrogen atmosphere. In oxygen atmosphere, the onset temperature (T0) of DMF oxidation is 323.49 K, and the activation energy (Ea) is 172.35 kJ/mol. The peroxide concentration of oxidation process was determined by iodometry, and the oxidation products were analyzed by gas chromatography - mass spectrometry. The pressure and exothermic behavior of ARC are related to the reaction mechanism. A simple three steps mechanism of DMF oxidation was described: fist DME reacts with oxygen to form peroxide; second is the main oxidation stage, oxidation products are complex; the third step is thermal decomposition.
- Huang, Pinxian,Kubota, Shiro,Liu, Pin,Liu, Xiongmin,Saburi, Tei,Wada, Yuji
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- Oxygen bridged Homobinuclear Mn(II) compounds with Anthranilic acid: Theoretical calculations, oxidation and catalase activity
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Two new homobinuclear manganese compounds with mixed ligands, [Mn2(μ1,1–2-NH2C6H4COO)2(phen)4](ClO4)2(CH3OH) (1), and [Mn2(μ1,3–2-NH2C6H4COO)2(bipy)4](ClO4)2 (2) (NH2C6H4COOH?=?anthranilic acid, bipy?=?2,2′-bipyridine, phen?=?1,10- phenanthroline) were synthesized and thoroughly characterized by elemental analysis, IR, UV and single crystal X-ray crystallography. X-ray structure analysis shows that in the mono- and bidentate carboxylate bridged compounds, Mn–Mn distances of 1 and 2 are 3,461??, and 4,639??, respectively. The energy of the compounds was determined with a DFT (Density Functional Theory) calculation on B3LYP/6-31G(d,p) optimized geometry by using the B3LYP/6-31G(d,p) basis set. These compounds acts as biomimetic catalyst and show catalase-like activity for the hydrogen peroxide dismutation at room temperature in different solvents with remarkable activity (TOF, Turnover frequency?=?mol of subst./(mol of cat. × time)) up to 12640?h?1 with 1, and 17910?h?1 with 2 in Tris–HCl buffer). Moreover, the catalytic activity of 1 and 2 has been studied for oxidation of alcohols (cinnamyl alcohol, benzyl alcohol, cyclohexanol, 1-octanol and 1-heptanol) and alkenes (cyclohexene, styrene, ethyl benzene, 1-octene and 1-hexene) in a homogeneous catalytic system consisting t-butylhydroperoxide (TBHP) as an oxidant in acetonitrile. Both compounds exhibited very high activity in the oxidation of cyclohexene to cyclohexanone (~80% selectivity, ~99% conversion in 1?h, TOF?=?243?h?1 and 226?h?1) and cinnamyl alcohol to cinnamaldehyde (~64% selectivity) as the main product with very high TOF value (9180?h?1 and 13040?h?1 in the first minute of reaction) (~100% conversion in 0.5?h) with TBHP at 70?°C in acetonitrile, for 1 and 2, respectively.
- Su, Esra,Guven, Alaettin,Kani, Ibrahim
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- 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
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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
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p. 457 - 466
(2014/02/14)
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- Low catalyst loading in the cross metathesis of olefins with methyl vinyl ketone
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An olefin-metathesis catalyst featuring a 1,3-bis(2,6-diisopropylphenyl)-4, 5-dihydroimidazol-2-ylidene N-heterocyclic carbene and an ester-chelating carbene ligand efficiently promoted the cross metathesis of olefins with 3-buten-2-one in the presence of copper iodide as cocatalyst. At optimized reaction conditions a 10-20 times lower catalyst loading compared to the state of the art could be achieved. Georg Thieme Verlag Stuttgart New York.
- Abbas, Muddasar,Leitgeb, Anita,Slugovc, Christian
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p. 1193 - 1196
(2013/07/11)
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- New Syntheses of Geiparvarin and 2,5-Dimethyl-3(2H)-furanone via CO2 Mediated Bond Reorganization
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A new synthesis of 3(2H)-furanones from 4-hydroxy-2-alkyn-1-one derivatives via CO2 mediated bond reorganization has been developed to the preparation of an antitumor agent, geiparvarin and a constituent of flavors, 2,5-dimethyl-3(2H)-furanone.
- Inoue, Y.,Ohuchi, K.,Imaizumi, S.,Hagiwara, H.,Uda, H.
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p. 3063 - 3068
(2007/10/02)
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- REACTIONS DE L'OZONE SUR DES MOLECULES PHOSPHOREES: OZONIDES
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Ozone reacts very rapidly with alkylidenetriphenylphosphoranes 1a-d.In all cases we observed the cleavage of the P=C bond and formation of triphenylphosphine oxide and the corresponding ketone 4a, 4b (R1 = Ph) and alkene 4c (R1 = H).Ozone also reacts with substituted phosphites 5a-b and gives the ozonides 7a-b.
- Caminade, A. M.,Khatib, F. el,Koenig, M.
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p. 381 - 384
(2007/10/02)
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