نتایج جستجو برای: dibenzo xanthenes
تعداد نتایج: 2380 فیلتر نتایج به سال:
Research on the behavior and fate of pesticides in the environment has provided a number of valuable techniques for assessing the impact of any organic substance intentionally or unintentionally released in the environment. These techniques can be applied to the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to determine its behavior under comparable conditions. Important parameters affecting the e...
A palladium-mediated intramolecular aryl–aryl coupling reaction was applied to the total synthesis of bioactive natural products, graphislactone G (1), and palmariols (2) B (3), which possess an unusual chloro-subsutituent on 6H-dibenzo[b,d]pyran-6-one skeleton. Based transition state model reaction, mechanistic aspect for regioselectivity is also discussed.
The potential of polycyclic aromatic hydrocarbons (PAHs) to modulate microsomal epoxide hydrolase activity, determined using benzo[a]pyrene 5-oxide as substrate, in human liver, was evaluated and compared to rat liver. Precision-cut liver slices prepared from fresh human liver were incubated with six structurally diverse PAHs, at a range of concentrations, for 24h. Of the six PAHs studied, benz...
this paper describes the applicability of 1,3-dichloro-5,5-dimethylhydantoin, as a cheap, stable and commercially available catalyst, in the promotion of the synthesis of 1,8-dioxo-octahydro-xanthenes (doxos) via the one-pot condensation of aldehydes and cyclic 1,3-dicarbonyl compounds. this novel synthetic method has the advantages of high yields, short reaction times, low cost and availabilit...
In the title triazolothia-diazine derivative, C(20)H(16)N(6)O(3)S {systematic name: 3-(4-methyl-phen-yl)-4-[3-(phen-oxy-meth-yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thia-diazin-6-yl]-1,2,3-oxadiazol-3-ium-5-olate}, an S(6) ring motif is generated by an intra-molecular C-H⋯O hydrogen bond. The 3,6-dihydro-1,3,4-thia-diazine ring adopts a twist-boat conformation. The dihedral angle between the 1,2,3-o...
Regio- and conformational isomerization are fundamental in chemistry, with profound effects upon physical properties, however their role in excited state properties is less developed. Here two regioisomers of bis(10H-phenothiazin-10-yl)dibenzo[b,d]thiophene-S,S-dioxide, a donor-acceptor-donor (D-A-D) thermally-activated delayed fluorescence (TADF) emitter, are studied. 2,8-bis(10H-phenothiazin-...
Atmospheric deposition is a significant loading pathway for polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxin) to the Great Lakes. An innovative approach using NOAA's HYSPLIT atmospheric fate and transport model was developed to estimate the 1996 dioxin contribution to each lake from each of 5,700 point sources and 42,600 area sources in a U.S./Canadian air emissions inventory. These ...
The International Agency for Research on Cancer (IARC) Monographs program reevaluated polychlorinated dibenzo-p-dioxins and evaluated polychlorinated dibenzofurans as possible carcinogenic hazards to humans in February 1997, using the most recent epidemiologic data on exposed human populations, experimental carcinogenicity bioassays in laboratory animals, and supporting evidence on relevant mec...
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