Anodic Oxidation of Unsaturated Aliphatic Ethers in aqueous electrolytes
摘要:
2,5-dihydrofuran 1 was galvanostatically oxidized in aqueous electrolytes on Pt and PbO2 anodes at current densities of 10 to 50 mA cm(-2). Under acidic conditions maleic dialdehyde 2 was obtained on bath electrodes with a current efficiency (c.e.) of up to 50%. In the alkaline region (pH 10) 4-hydroxy crotonic aldehyde 3 (Pt) or 2,5-dihydrofuranone 4 (PbO2) become the main products with c.e.'s of 29% and 27%, respectively, depending on the anode material. The influence of pH and of the anode material are discussed in detail. 2,3-dihydrofuran 7, vinyl ethyl ether 8 and for comparison, furan 9 were studied in addition.
作者:Björn Klotz、Ian Barnes、Karl H. Becker、Bernard T. Golding
DOI:10.1039/a606152d
日期:——
The atmospheric chemistry of benzene oxide/oxepin, a possible
intermediate in the atmospheric oxidation of aromatic hydrocarbons,
has been investigated in a large volume photoreactor at 298 K and
atmospheric pressure using in situ FTIR spectroscopy
for the analysis. Rate coefficients of
(10.0±0.4)×10
-11
and
(9.2±0.3)×10
-12
cm
3
molecule
-1
s
-1
have been determined for the
reaction of benzene oxide/oxepin with OH and NO
3
radicals,
respectively. Reaction with OH radicals produces almost exclusively
the (E,Z)- and (E,E)-isomers of
hexa-2,4-dienedial, whereas reaction with NO
3
produces
(Z,Z)-hexa-2,4-dienedial and unidentified organic
nitrates. Phenol has been observed as a major product of the thermal
decomposition, visible and UV photolysis of benzene oxide/oxepin. The
results are discussed in conjunction with the oxidation mechanisms of
aromatic hydrocarbons. The major atmospheric sinks of benzene
oxide/oxepin will be reaction with OH radicals and photolysis and,
under smog chamber conditions with high NO
2
concentrations,
also reaction with NO
3
.
Gas-phase reaction of OH radicals with benzene: products and mechanism
作者:Torsten Berndt、Olaf Böge
DOI:10.1039/b106667f
日期:——
The gas-phasereaction of OH radicals with benzene was studied in O2/He mixtures under flow conditions in the temperature range 276–353 K and at pressures of 100 and 500 mbar using on-line FT-IR spectroscopy and GC-MS measurements. The reaction conditions were chosen so that the initially formed OH/benzene adduct predominantly reacted either with O2 or O3. Under conditions of a predominant reaction
使用在线 FT-IR 光谱和 GC-MS 测量,在 276–353 K 温度范围和 100 和 500 mbar 压力下,在 O2/He 混合物中研究了 OH 自由基与苯的气相反应。选择反应条件以使最初形成的OH/苯加合物主要与O2或O3反应。在 OH/苯加合物与 O2 的主要反应条件下,研究了不同 NO 浓度的产物形成。鉴定产物为六-2,4-二烯二醛、苯酚、硝基苯、对苯醌和乙二醛的异构体。发现少量呋喃。随着 NO 浓度的增加,苯酚产率降低,反式、反式-六-2,4-二烯二烯和硝基苯的产率增加,最大值分别为 0.36 ± 0.02 和 0.11 ± 0.02,分别(100 毫巴,295 K)。发现 0.08 ± 0.02 的对苯醌产率与 NO 浓度无关。在 500 mbar 下,[NO]/[O2] = 1-20 × 10-6 的初始比率在 276-353 K 范围内测量苯酚产率的温度依赖性。对于固定的
Oxidation of furans with dimethyldioxirane. Interception of malealdehyde and related aldehydes via Wittig reactions
作者:Brian J. Adger、Collette Barrett、Joseph Brennan、Peter McGuigan、M. Anthony McKervey、Brian Tarbit
DOI:10.1039/c39930001220
日期:——
Unsaturated aldehydes including malealdehyde, generated in acetone by oxidation of furans with dimethyldioxirane, can be trapped efficiently by phosphoranes in Wittig reactions.
Chemical Synthesis and Pharmacology of 6- and 7-Hydroxylated 2-Carbomethoxy-3-(<i>p</i>-tolyl)tropanes: Antagonism of Cocaine's Locomotor Stimulant Effects
作者:Lianyun Zhao、Kenneth M. Johnson、Mei Zhang、Judith Flippen-Anderson、Alan P. Kozikowski
DOI:10.1021/jm000141b
日期:2000.8.1
synthesis to construct an appropriately functionalized tropane ring followed by use of a Suzuki coupling reaction to introduce the aryl group at position 3. Reduction of the resulting tropene by use of SmI(2) or by catalytic hydrogenation followed by deprotection delivered the final target compounds. Some of these compounds were found to retain considerable affinity as inhibitors of the dopamine transporter
Comparative Metabolism of Furan in Rodent and Human Cryopreserved Hepatocytes
作者:Leah A. Gates、Martin B. Phillips、Brock A. Matter、Lisa A. Peterson
DOI:10.1124/dmd.114.057794
日期:2014.7
Furan is a liver toxicant and carcinogen in rodents. Although humans are most likely exposed to furan through a variety of sources, the effect of furan exposure on human health is still unknown. In rodents, furan requires metabolism to exert its toxic effects. The initial product of the cytochrome P450 2E1-catalyzed oxidation is a reactive α , β -unsaturated dialdehyde, cis -2-butene-1,4-dial (BDA). BDA is toxic and mutagenic and consequently is considered responsible for the toxic effects of furan. The urinary metabolites of furan in rats are derived from the reaction of BDA with cellular nucleophiles, and precursors to these metabolites are detected in furan-exposed hepatocytes. Many of these precursors are 2-( S -glutathionyl)butanedial-amine cross-links in which the amines are amino acids and polyamines. Because these metabolites are derived from the reaction of BDA with cellular nucleophiles, their levels are a measure of the internal dose of this reactive metabolite. To compare the ability of human hepatocytes to convert furan to the same metabolites as rodent hepatocytes, furan was incubated with cryopreserved human and rodent hepatocytes. A semiquantitative liquid chromatography with tandem mass spectrometry assay was developed for a number of the previously characterized furan metabolites. Qualitative and semiquantitative analysis of the metabolites demonstrated that furan is metabolized in a similar manner in all three species. These results indicate that humans may be susceptible to the toxic effects of furan.