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1.
Ozonolysis of a Series of Methylated Alkenes: Reaction Rate Coefficients and Gas‐Phase Products
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Tristan Braure Véronique Riffault Alexandre Tomas Romeo Iulian Olariu Cecilia Arsene Yuri Bedjanian Patrice Coddeville 《国际化学动力学杂志》2015,47(9):596-605
The gas‐phase ozonolysis of three methylated alkenes, i.e., trans‐2,2‐dimethyl‐3‐hexene (22dM3H), trans‐2,5‐dimethyl‐3‐hexene (25dM3H), and 4‐methyl‐1‐pentene (4M1P), has been investigated in the presence of sufficient hydroxyl radical scavenger in a laminar flow reactor at ambient temperature (296 ± 2 K) and P = 1 atm of dry air (RH ≤ 5%). Ozone levels in the reactor were monitored by an automatic analyzer. Alkene and gas‐phase product concentrations were determined via online sampling either on three‐bed adsorbent cartridges followed by thermodesorption and GC/FID‐MS analysis or on 2,4‐dinitrophenylhydrazine (DNPH) cartridges for subsequent HPLC/UV analysis. Reaction rate coefficients of (3.38 ± 0.12) × 10?17 for 22dM3H and (2.71 ± 0.26) × 10?17 for 25dM3H, both in cm3 molecule?1 s?1 units, have been obtained under pseudo–first‐order conditions. Primary carbonyl products have been identified for the three investigated alkenes, and branching ratios are reported. In the case of 4M1P ozonolysis, the yield of a Criegee intermediate was indirectly determined. Kinetics and product study results are compared to those of literature when available. This work represents the first investigation of reaction products in the ozonolysis of 22dM3H, 25dM3H, and 4M1P in a flow reactor. 相似文献
2.
The effect of bacterial and fungal activities on organic matter degradation in Brazilian soils was studied by a microcalorimetric method. Bacteria and fungi isolated from tropical soils and added to: Rhodic eutrudox (R), Typic eutrudox (V) and Quartzipsamment (Q) soils amended separately with moisture (control) (A) and 25% of cattle manure (E), municipal refuse compost (L), earthworm casts (H) or 23 μg of trifluralin (T) were investigated. The number of colony forming units in soil suspension was quantified by microscopy and inoculated in respective soil. All processes were measured at intervals of 7 days over a period of 35 days. The exothermic thermal effect (μJ) per cm3 of bacteria or fungi per gram of dry soil, respectively, for each substrate was: [(9±1), (4±1)] RA; [(478±24), (105±5)] RE; [(121±6), (71±4)] RL; [(121±6), (71±4)] RH; [(8±1); (3±1)] RT; [(10±1), (9±1] VA; [(347±17), (261±13)] VE; [(71±4), (28±1)] VL; [(22±1), (33±2)] VH; [(7±1), (10±1)] VT; [(19±1), (12±1)] QA; [(1301±65), (46±2)] QE; [(89±4), (9±1)] QL; [(130±7), (11±1)] QH; [(32±2), (8±1)] QT. The calorimetric values are higher for bacteria than for fungi. In general, the results showed higher activities in the soil amended with cattle manure than with other additives. 相似文献
3.
Fulvia Orsini Guido Sello Silvana Bernasconi Gianfranco Fallacara 《Tetrahedron letters》2004,45(50):9253-9255
Several conduritol and conduramine analogues have been synthesized from β-substituted naphthalenes via a chemoenzymatic approach, in a high regio- and stereocontrolled way. 相似文献
4.
The thermal decomposition of some mixed uranyl complexes with Schiff bases and DMSO, EtOH or (Ph)3PO as neutral ligand, were investigated and the corresponding activation energy, E*a, and enthalpy of dissociation, ΔHd, values were calculated.
The results obtained indicate that for the same neutral ligand, the thermal stability of the uranyl complexes is influenced by the Schiff base used; for the same Schiff base, the presence of (Ph)3PO results in a greater thermal stability of the mixed complexes than when the other two neutral ligands are present. 相似文献
5.
Treatment of 2,3-diketo-cholestane (1) with thallium triacetate in acetic acid afforded mainly 3α-carbomethoxy-A-nor-5α-cholestan-2-one (2). Under similar conditions, the 3,4-diketo steroids (3 and 4) underwent extensive rearrangement affording spiro-lactones (9 and 10), in low yields. The structural assignment of the spiro-cholestane derivative was supported by crystallographic X-ray analysis. This product was the result of A and B-ring contractions followed by acid-catalysed cyclization of an unsaturated carboxy intermediate. 相似文献
6.
Antonino Mazzaglia Domenico Garozzo Raffaello Romeo 《Journal of organometallic chemistry》2005,690(8):1978-1985
MALDI and ESI-MS have been applied to the characterization of the reaction products between the labile cis-[Pt(DMSO)2Cl2] (1) and trans-[Pt(DMSO)2Cl(CH3)] (2) complexes with the simplest poly(amidoamine) ligand (PAMAM, G = 0, 1,2-diaminoethane as core). The comparison of the mass spectra of the starting G0 and those of the metallo-dendrimers formed upon mixing of the reagents in an equimolecular ratio, and the analysis of the isotopic distribution in the ESI spectra, have revealed the formation of cationic and neutral mononuclear complexes with PAMAM as ligand, e.g., cis-[Pt(DMSO)(PAMAM)Cl]Cl or trans-(C,N)[Pt(DMSO)(PAMAM)Cl(CH3)], together with various minor components, which have been identified as derivatives from defective structures of PAMAM. The geometry of the main products has been deduced from the values of the protons coupling constants with the isotopically abundant 195Pt. The metal-to-ligand bond is restricted to the peripheral amino groups of PAMAM which shows sufficient flexibility to involve either one or two branches in the coordination bonding. 相似文献
7.
Tarozzi A Marchesi A Hrelia S Angeloni C Andrisano V Fiori J Cantelli-Forti G Hrelia P 《Photochemistry and photobiology》2005,81(3):623-629
Ultraviolet-A (UVA) radiation causes significant oxidative stress because it leads to the generation of reactive oxygen species (ROS), leading to extensive cellular damage and eventual cell death either by apoptosis or necrosis. We evaluated the protective effects of cyanidin-3-O-beta-glucopyranoside (C-3-G) against UVA-induced apoptosis and DNA fragmentation in a human keratinocyte cell line (HaCaT). Treatment of HaCaT cells with C-3-G before UVA irradiation inhibited the formation of apoptotic cells (61%) and DNA fragmentation (54%). We also investigated antioxidant properties of C-3-G in HaCaT cells against ROS formation at apoptotic doses of UVA; C-3-G inhibited hydrogen peroxide (H2O2) release (an indicator of cellular ROS formation) after UVA irradiation. Further confirmation of the potential of C-3-G to counteract UVA-induced ROS formation comes from our demonstration of its ability to enhance the resistance of HaCaT cells to the apoptotic effects of both H2O2 and the superoxide anion (O2*-), two ROS involved in UVA-oxidative stress. Furthermore, in terms of Trolox Equivalent Antioxidant Activity, C-3-G treatment led to a greater increase in antioxidant activity in the membrane-enriched fraction than in the cytosol (55% vs 19%). The protective effects against UVA-induced ROS formation can be attributed to the higher membrane levels of C-3-G incorporation. These encouraging in vitro results support further research into C-3-G (and other anthocyanins) as novel agents for skin photoprotection. 相似文献
8.
9.
Ficarra P. Ficarra R. Chimirri A. Romeo G. Tommasini S. Calabrò M. L. Costantino D. Monforte A. M. Carulli M. 《Chromatographia》1994,38(1-2):57-61
Summary Anti-HIV enantiomeric 1H, 3H-thiazolo[3, 4-a] benzimidazoles have been stereospecifically analyzed by elution on a column of cellulose tris-(4-methyl-phenylbenzoate)ester adsorbed on macroporous silica (ChiralcelR OJ).The enantiomeric resolution of the compounds examined is linked to a complex and competitive contribution of different factors. 相似文献
10.