benzofurans and ferric-chloride

Iron chloride is often cited as catalyst of PCDD/F-formation, together with copper chloride. Conversely, iron chloride catalysis has been less studied during de novo tests. This paper presents such de novo test data, derived from model fly ash incorporating iron (III) chloride and established over a vast range of temperature and oxygen concentration in the gas phase. Both PCDD/F-output and its signature are extensively characterised, including homologue and congener profiles. For the first time, a complete isomer-specific analysis is systematically established, for all samples. Special attention is paid to the chlorophenols route PCDD/F, to the 2,3,7,8-substituted congeners, and to their relationship and antagonism.

Topics: Benzofurans; Catalysis; Chlorides; Chlorophenols; Coal Ash; Copper; Ferric Compounds; Incineration; Iron; Models, Chemical; Polychlorinated Dibenzodioxins; Temperature

A general synthesis of 3-chalcogen benzo[b]furans from the readily available 2-alkynylanisoles, via FeCl(3)/diorganyl dichalcogenides intramolecular cyclization, has been developed. Aryl and alkyl groups directly bonded to the chalcogen atom were used as cycling agents. The results revealed that the reaction significantly depends on the electronic effects of substituents in the aromatic ring bonded to the selenium atom of the diselenide species. We observed that the pathway of reaction was not sensitive to the nature of substituents in the aromatic ring of anisole since both the electron-donating and the electron-withdrawing groups delivered the products in similar yields. In addition, the obtained heterocycles were readily transformed to more complex products by using a chalcogen/lithium exchange reaction with n-BuLi followed by trapping of the lithium intermediate with aldehydes, furnishing the desired secondary alcohols in good yields.

Topics: Anisoles; Benzofurans; Chalcogens; Chlorides; Cyclization; Ferric Compounds; Molecular Structure; Stereoisomerism

Surface water from Guangzhou to which standard polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were added was treated by coagulation with ferric chloride (FC), polyaluminium chloride (PAC), and aluminium sulfate (AS) at optimum removal dosages for nature organic matter (NOM) to assess the polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) removal efficiencies. PCDD/Fs in suspended particulate matter (SPM) and treated water (TW) after coagulation were analysed. Low residual levels of PCDD/Fs were found in treated water after coagulation: 0.8% for FC, 0.9% for PAC, and 3.1% for AS. The removal efficiency calculated using these results was >99% for FC and PAC and 97-98% for AS. Most PCDD/Fs congeners could be removed by the three coagulation processes; the removal efficiency of FC and PAC was similar, and slightly higher than that of AS. The results also demonstrate that coagulation with FC preferentially removed tetra- and penta-substituted PCDD/Fs from raw water.

Topics: Alum Compounds; Aluminum Chloride; Aluminum Compounds; Benzofurans; China; Chlorides; Dibenzofurans, Polychlorinated; Ferric Compounds; Polychlorinated Dibenzodioxins; Quality Control; Water Pollution, Chemical; Water Supply

A variety of 3-functionalized benzo[b]furans were achieved by way of a FeCl(3)-mediated intramolecular cyclization of electron-rich alpha-aryl ketones. The alkoxy substituent on the benzene ring in the substrates was essential for an efficient cyclization to occur. This novel method allows the construction of benzo[b]furan rings by joining the O-atom on the side chain to the benzene ring via direct oxidative aromatic C-O bond formation.

Topics: Benzofurans; Catalysis; Chlorides; Combinatorial Chemistry Techniques; Cyclization; Ferric Compounds; Ketones; Molecular Structure; Oxidation-Reduction; Stereoisomerism