Mercury compounds furans

Mercury compounds are seldom used in modern furan chemistry. Deuterodemercuration finds use in the preparation of deuterofurans (Scheme 110) (,74JCS. 3-Chloromer-... 

The most relevant problem originating from MSW incineration is flue gas treatment, since untreated incineration flue gas can contain large amounts of macropollutants (e.g., CO, S02, HC1, NOx, particulates) andmicropollutants (e.g., PAHs, mercury compounds, polychlorinated biphenyls, dioxins, furans). The necessity of reducing polluting emissions to levels compatible with existing regulations dictates the adoption of rather sophisticated- and expensive flue gas treatment sections in incineration plants. 

The furan reaction was shown to be an equilibrium, and to be catalyzed by mercuric chloride 116). Tris(2-furyl)arsine has also been prepared by Wurtz-Fittig and Grignard procedures 119). The most recent use of mercury compounds has been in the preparation of dichloroperfluorovinyl-arsine 120,121). 

The generation of 2,3-didehydrothiophene (4) under thermolysis conditions has been attempted and claimed several times. Among the clearly unsuccessful attempts are the gas phase thermolyses of 2,3-diiodothiophene (360) and 2-nitrothiophene (361) which, in spite of the prominence of an ion corresponding to the aryne (4) in their mass spectra,apparently give no products indicating an aryne intermediate even in the presence of several potential diene traps such as benzene " and furan. As with the mercury compound 286 (Section III.3.A.a) the major decomposition pathway appears to involve homolysis of the bond to the 2-substituent. ... 

Mercury(II) acetate tends to mercurate all the free nuclear positions in pyrrole, furan and thiophene to give derivatives of type (74). The acetoxymercuration of thiophene has been estimated to proceed ca. 10 times faster than that of benzene. Mercuration of rings with deactivating substituents such as ethoxycarbonyl and nitro is still possible with this reagent, as shown by the formation of compounds (75) and (76). Mercury(II) chloride is a milder mercurating agent, as illustrated by the chloromercuration of thiophene to give either the 2- or 2,5-disubstituted product (Scheme 25). 

Pyrrole polymerises under reducing conditions, Tliiophene-2-carboxylic acid is reduced in alkaline solution at -2.3 V v v. see, on a mercury cathode, to the 2,5-dihydro compoimd [61], Under these same conditions, furan-2-carboxylic acid is also reduced to the 2,5-dihydro compound [62]. 

Photolysis of oxetane, 2,2-dimethyloxetane and 2-phenyloxetane has been found to occur slowly with mercury arc irradiation. The products are similar to those observed from pyrolysis of these compounds. Oxo-substituted oxetanes are probably much more susceptible to photolysis. Irradiation of oxo-oxetane (28) at 350 nm isomerized it to a furan (29) and a dioxalene (30), each of which can be explained by cleavage of the oxetane ring to a 1,4-biradical (69CC572). 

Other compounds that have been similarly synthesized are 2,4-bis(4-methoxyphenyl)furan, 2,4-bis(4-biphenylyl)furan, 2,4-bis(4-bromophenyl)furan, 2,4-bis(4-chlorophenyl)furan, and 2,4-bis(4-nitrophenyl)furan. When MeOH (a proton donor) is added to the system containing phenacyl bromide [232], the principal products are acetophenone (53%) and 2-bromo-l,3-diphenyl-3,4-epoxy-butan-l-one (37%). If, to DMF containing lithium perchlorate and ethyl bromoacetate, phenacyl bromide is slowly introduced and reduced at mercury, the distribution of products is different [233] ... 

Representative Chemicaes Aldrin (CAS 309-00-2) Dieldrin (CAS 60-57-1) Alkyl-lead (CAS 7439-92-1) Benzo(d )pyrene (CAS 50-32-8) Chlordane (CAS 57-74-9) Dichlorodiphenyltrichloroethane (DDT) (CAS 50-29-3) Hexachlorobenzene (CAS 118-74-1) Mercury and compounds (CAS 7439-97-6) Mirex (CAS 2385-85-5) Octachlorostyrene (CAS 29082-74-4) Polychlorinated biphenyls (PCBs) (CAS 11097-69-1 for Arochlor 1254) 2,3, 7,8-Tetrachlorodibenzo-/7-dioxin (TCDD) (CAS 1746-01-6) and chemically similar compounds collectively known as dioxins and furans Camp-hechlor (toxaphene) (CAS 8001-35-2)... 

Furan-2-carbaldehyde has been much studied. A thorough analysis of the first two major electronic transitions has been carried out. Practical work is hampered by the resinification of the compound and by the presence of a trace impurity which gives rise to a long-lived pressure-independent component in the phosphorescence spectrum.23 The absence of n ->n excited emission and other facts implicate a very efficient double intersystem crossing.14 24 Whether or not sensitized by mercury, photodecomposition of the aldehyde gives much carbon monoxide, propyne, and allene. Small amounts of furan, carbon dioxide, and acetylene are also formed. 

As described in the previous section, the Dewar thiophene is a suitable dienophile and reacts with many kinds of dienesU9). If the sulfur atom of the thiirane part can be eliminated, the Dewar thiophene will be a suitable precursor of a C4(CF3)4 unit. An example is the synthesis of oxahomocubanes. Thus, the Diels-Alder adducts from the Dewar thiophene and furans were treated with triphenylphosphine and irradiated with a low-pressure mercury lamp to give oxahomocubanes (119). A peculiar point is the fact that exo-tricyclic compound is eyclized. Therefore, isomerization should have occurred prior to cyclization. This suggests that photocyclization cannot be used for the determination of such configurations110). 

Diverse chemicals have been reported to affect measured endpoints of fish thyroidal status. These chemicals include aromatic hydrocarbons, planar halogenated aromatic hydrocarbons (dioxans, furans, coplanar PCBs), organochlorine, organophosphorus and carbamate pesticides, chlorinated paraffins, cyanide compounds, methyl bromide, phenol, ammonia, metals (aluminum, arsenic, cadmium, lead and mercury), low pH conditions, environmental steroids and a variety of pharmaceutical agents. For the following reasons their modes of action appear complex and are poorly understood16. 

The reaction of aryllead triacetates is not limited to substituted phenyllead derivatives. It has also been extended to the use of heteroaryllead compounds, derived from furan and thiophene.Due to their relative instability and moisture-sensitivity, they are best prepared by metal exchange, such as mercury-lead or tin-lead, and used in situ in the reactions of carbon nucleophiles. 

Treatment of the quaternary ammonium salt PhC=CCH2NMe2CH2COPh Br" with sodium hydroxide gives, inter alia, the betaine (98). Controlled-potential electrolysis of 7-nitro-ketones on a mercury cathode yields 1-pyrroline 1-oxides, pyrrolines, or pyrrolidines, according to conditions thus the oxide (99) is obtained from the compound 02NCMe2CHPhCH2C0Ph. The pyrrolinone (101) results from autoxidation of the furan derivative (100). Irradiation of the amide (102) leads to the pyrrolidinone (103) by an unprecedented [1,6] shift of hydrogen. " ... 

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