Trichloromethanes

Trichloromethane (chloroform) is a widely used industrial and academic laboratory solvent. In contrast to CH2C12, CHC13 has a multitude of natural sources, both biogenic and abiotic (1), and several excellent reviews are available (303-305). Noteworthy is the estimate that greater than 90% of atmospheric CHC13 is of natural origin (Table 3.3). 

The combustion of biomass, which invariably contains carbon and chloride, produces CHCI3, although the amount is much less than that recorded for CH3C1 and CH2C12 (283, 286) and is a minor emission source of CHC13 ( 1%) (303-305) (Table 3.3). The high temperature (700°C) reaction of methane, HC1, and oxygen furnishes trichloromethane (232). 

Following the pioneering studies of Isidorov (218), other investigations find CHC13 in several Italian (Vulcano, Mt. Etna) and Japan (Kuju, Satsuma-Iwojima) volcanoes (216, 217), but the amounts are relatively small (216). 

Phosgene is a common impurity in liquid trichloromethane (chloroform) and arises from aerial oxidation, accelerated by exposure to sunlight [134], Indeed, oxidation occurs neither by air in the absence of sunlight nor by light in the absence of air. 

Phosgene is potentially derivable from trichloromethane in contact with a wide variety of oxidising agents, and only selected systems are described in this Section. The early 

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The gas phase chlorination of methane is a reaction of industrial importance and leads to a mixture of chloromethane (CH3CI) dichloromethane (CH2CI2) trichloromethane (CHCI3) and tetrachloromethane (CCI4) by sequential substitution of hydrogens... 

One of the chief uses of chloromethane is as a starting material from which sili cone polymers are made Dichloromethane is widely used as a paint stripper Trichloromethane was once used as an inhalation anesthetic but its toxicity caused it to be replaced by safer materials many years ago Tetrachloromethane is the starting mate rial for the preparation of several chlorofluorocarbons (CFCs) at one time widely used as refrigerant gases Most of the world s industrialized nations have agreed to phase out all uses of CFCs because these compounds have been implicated m atmospheric processes that degrade the Earth s ozone layer... 

Dichloromethane trichloromethane and tetra chloromethane are widely known by their common names methylene chloride chloroform and carbon tetrachloride respectively... 

Methane reacts with CI2 to give chloromethane dichloromethane trichloromethane and tetrachloromethane... 

Trihalomethanes. Wherever chlorine is used as a disinfectant in drinking-water treatment, trihalomethanes (THMs) generaUy are present in the finished water. The THMs usuaUy formed are trichloromethane (chloroform), bromodichloromethane, dibromochloromethane, and tribromomethane (bromoform). There are four main techniques for the analysis of THMs headspace, Hquid— Hquid extraction (Ue), adsorption—elution (purge—trap), and direct aqueous injection. The final step in each technique involves separation by gas—Hquid chromatography with a 2 mm ID coUed glass column containing 10 wt % squalene on chromosorb-W-AW (149—177 p.m (80—100 mesh)) with detection generaUy by electron capture. 

Chlorination of various hydrocarbon feedstocks produces many usehil chlorinated solvents, intermediates, and chemical products. The chlorinated derivatives provide a primary method of upgrading the value of industrial chlorine. The principal chlorinated hydrocarbons produced industrially include chloromethane (methyl chloride), dichloromethane (methylene chloride), trichloromethane (chloroform), tetrachloromethane (carbon tetrachloride), chloroethene (vinyl chloride monomer, VCM), 1,1-dichloroethene (vinylidene chloride), 1,1,2-trichloroethene (trichloroethylene), 1,1,2,2-tetrachloroethene (perchloroethylene), mono- and dichloroben2enes, 1,1,1-trichloroethane (methyl chloroform), 1,1,2-trichloroethane, and 1,2-dichloroethane (ethylene dichloride [540-59-0], EDC). 

Chloroethanol, see Ethylene chlorohydrin Chloroethylene, see Vinyl chloride Chloroform (trichloromethane)... 

Chemical Designations - Synonyms Trichloromethane Chemical Eormula CHClj. 

Halofluoroalkenes may be prepared by using fluorodihalomethanes or fluoro-halomethanes in olefination procedures similar to those descnbed above. Ruoro-trichloromethane treated with tris(dimethylamino)phosphine forms the corresponding phosphomum salt, which can then be used in the Wirtig procedure. The reaction depends on the nature of the solvent in tetrahydrofuran, little olefination if any occurs however, when benzomtrile is added to the mixture, ylide formation is promoted [50] (equation 48) (Table 19). 

Not many reactions between A-(l-haloalkyl)heteroarylium halides and anionic nucleophiles are reported in the literature. In trichloromethane or... 

A mixture of 22 parts of 1 -ethyl-1,4-dihydro-5H-tetrazol-5-one,45 parts of 1 -bromo-2-chloro-ethane,26 parts of sodium carbonate,0.3 part of potassium iodide and 240 partsof 4-methyl-2 pentanone is stirred and refluxed overnight with water-separator. The reaction mixture is cooled, water is added and the layers are separated. The aqueous phase is extracted three times with dichloromethane. The combined organic phases are dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using trichloromethane as eluent. The pure fractions are collected and the eluent is evaporated, yielding 28.4 parts (80%) of 1-(2-chloroethyi)-4-ethyl-1,4-dihydro-5H-tetrazol-5-one as a residue. 

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