From halogenated hydrocarbons

Belay N, L Daniels (1987) Production of ethane, ethylene and acetylene from halogenated hydrocarbons by methanogenic bacteria. Appl Environ Microbiol 53 1604-1610. 

Molecular reactions are generally more difficult to treat because of the complexity of the possible transition states. The most widely studied complex molecular reaction class is HX elimination from halogenated hydrocarbons. These reactions proceed primarily via the formation of polar, four-centered tight transition states, and examples include... 

Stratospheric Ozone depletion is largely due to chlorine and bromine radicals released from halogenated hydrocarbons. This paper describes properties, emission histories and budgets of relevant substances and outlines the pertinent photochemical processes, along with a comprehensive presentation of halocarbon measurements and global distributions. 

There has been considerable interest in the elimination of hydrogen halides from halogenated hydrocarbon molecules and radicals which have been vibration-ally excited by chemical activation, by photochemical methods or by shock-tube techniques. Studies on fluorinated species have been reported by Trotman-Dickenson et a/.7 3.839-84i,846.908,909 by Pritchard et fl/.747,748.905.919.920 ... 

It is stored in a cold, dry, well-ventilated place separated from halogenated hydrocarbons and... 

Phosgene can be prepared from carbon monoxide, from halogenated hydrocarbons, from carbonaceous materials, from carbon dioxide, carbonyl sulfide or carbon disulfide, and from other oxygenated compounds [39]. The method based on the chlorination of carbon monoxide is by far the most important and has been scaled-up for the commercial manufacture of phosgene. 

From the mono-halogenated hydrocarbon. The halogenated hydrocarbon is converted into the Grignard reagent and the latter allowed to react with diethyl carbonate, for example ... 

It is important to produce HCl rather than elemental chlorine, CI2, because HCl can be easily scmbbed out of the exhaust stream, whereas CI2 is very difficult to scmb from the reactor off-gas. If the halogenated hydrocarbon is deficient in hydrogen relative to that needed to produce HCl, low levels of water vapor may be needed in the entering stream (45) and an optional water injector may be utilized. For example, trichloroethylene [79-01 -6] C2HCI2, and carbon tetrachloride require some water vapor as a source of hydrogen (45). 

Hydro-de-diazoniation seems to be an unnecessary reaction from the synthetic standpoint, as arenediazonium salts are obtained from the respective amines, reagents that are normally synthesized from the hydrocarbon. Some aromatic compounds, however, cannot be synthesized by straightforward electrophilic aromatic substitution examples of these are the 1,3,5-trichloro- and -tribromobenzenes (see below). These simple benzene derivatives are synthesized from aniline via halogenation, diazotization and hydro-de-diazoniation. Furthermore hydro-de-diazoniation is useful for the introduction of a hydrogen isotope in specific positions. 

Table I. Concentrations of halogenated hydrocarbons in organisms, (ng d.w.). The first number represents samples from the non-poUuted site, the second from polluted site...

Electrical and electronic waste can be successfully recovered by pyrolysis following a suitable amount of separation. It has been demonstrated that by selecting the correct processing parameters, any halogenated hydrocarbons present are satisfactorily destroyed. Oil and gas from the pyrolysis are best used to heat the pyrolysis kiln. The metal containing pyrolysis coke can be treated in a secondary copper smelter without need for further processing. 

Withey JR, Collins BT, Collins PG. 1983. Effect of vehicle on the pharmacokinetics and uptake of four halogenated hydrocarbons from the gastrointestinal tract of the rat. J Appl Toxicol 3 249-253. 

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