Perchloroethylene from ethylene

In contrast to many other countries, chlorinated solvents and the vinyl chain are of minor importance. Carbon tetrachloride (CTC), perchloroethylene (PCE), vinyl chloride monomer (VCM) and ethylene dichloride (EDC) were manufactured for over 40 years by ICI Australia in Sydney, but the facilities were small by world standards and were progressively closed (CTC/PCE in 1991, VCM in 1996 and EDC in 1998) as they were no longer able to compete against imports from world-scale plants overseas. 

The large volume solvents, trichloroethylene and perchloroethylene, are still chiefly made from acetylene, but appreciable amounts of the former are derived from ethylene. The competitive situation between these source materials runs through the whole chlorinated hydrocarbon picture, and extends on to other compound classes as well—for example, acrylonitrile is just on the threshold of a severalfold expansion, as demand grows for synthetic fibers based thereon. Acrylonitrile can be made either from ethylene oxide and hydrogen cyanide, from acetylene and hydrogen cyanide, or from allylamines. The ethylene oxide route is reported to be the only one in current commercial use, but new facilities now under construction will involve the addition of hydrogen cyanide to acetylene (27). 

There are three processes used in the making of perchloroethylene (tetra-chloroethylene melting point -19°C, boiling point 121°C, density 1.6227), but the majority is made from ethylene dichloride. 

Perchloroethylene and trichloroethylene are produced in a single-stage oxychlorination process from ethylene dichloride and chlorine. 

The process can accept a wide range of low-cost feedstocks, such as ethylene, chlorinated C2 hydrocarbons, and by-product streams from VCM chloromethanes, methyl chloroform, and EDC plants. The product ratio of trichloroethylene to perchloroethylene can be adjusted over a wide range. 

National Emission Standards for Coke Oven Batteries National Perchloroethylene Air Emission Standards for Dry Cleaning Facilities National Emission Standards for Chromium Emissions from Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks Ethylene Oxide Emissions Standards for Sterilization Facilities... 

Direct chlorination of vinyl chloride generates 1,1,2-tnchloroethane [79-00-5] from which vinylidene chloride required for vinylidene polymers is produced. Hydrochlorination of vinylidene chloride produces 1,1,1-trichloroethane [71-55-6], which is a commercially important solvent. Trichloroethylene and perchloroethylene are manufactured by chlorination, hydrochlorination, or oxychlorination reactions involving ethylene. Aromatic solvents or pesticides such as monochlorobenzene, dichlorobenzene, and hexachlorobenzene are produced by reaction of chlorine with benzene. Monochlorobenzene is an intermediate in the manufacture of phenol, insecticide DDT, aniline, and dyes (see Chlorocarbons a>td Chlorohydrocarbons.)... 

The solvents that are mostly employed include volatile organic solvents (VOCs) like methylene chloride, chloroform, perchloroethylene (PERC) and carbon tetrachloride. Some VOCs like, isopropyl alcohols, xylenes, toluenes and ethylenes have been used as cleaning fluids because of their ability to dissolve oils, waxes and greases. Also, they readily evaporate from the items that they are being used to clean (VOCs readily evaporate or vaporise at room temperature). When VOCs come in contact with sun light and nitrogen oxides (by-products from the combustion of fossil fuels), these are transformed into ozone, nitric acid and partially oxidised organic compounds. 

Carbon tetrachloride may also be co-produced with perchloroethylene, by chlorination of propane, propylene, ethylene, or on its own from a whole series of chlorinated residues. 

The general impression is of a widespread distribution, at the pg/1 level, of chloroform, carbon tetrachloride, trichloroethylene, perchloroethylene and methyl chloroform methyl chloride, vinyl chloride and ethylene dichloride are virtually absent, despite the large quantity of each known to be produced while methylene chloride is reported locally, and such compounds as hexachlorobutadiene at very low levels only in waters known to be affected by production effluents. There is, nevertheless, a very wide variation about these typical values, of at least 3 orders of magnitude it is difficult, therefore, to quote fully representative levels. Surface waters provide a much lower potential for widespread mixing than does the atmosphere, where concentrations of constituents are much more consistent. Many surface waters also contain the 3 brominated THMs these are probably derived from discharges of chlorinated potable water after use. 

The undesirable effects of chlorinated pesticides and PCB are closely associated with their tendency to accumulate in the fatty tissues of animals, where they are found at concentrations rising to hundred of parts per million. By contrast, the concentrations reported for the C1-C2 chlorocarbons are of the order of a few parts per billion which is three to five orders of magnitude lower [43]. The significant compounds (Table 7) are chloroform and carbon tetrachloride, trichloroethylene, perchloroethylene and methyl chloroform. Methyl chloride, methylene chloride and ethylene dichloride were not detected but the analytical method used did not resolve lower MW compounds while traces of hexachloro-butadiene were found in some marine organisms from an area known to receive industrial effluents. The compounds found in the animals were also found in a few samples of marine algae but at the time of sampling, the analytical method for methyl chloride was not adequate to show its presence. 

In the case of fish, exposed to solutions in water, some accumulation occurs, especially in the liver, bioconcentration factors reported range from 2 for ethylene dichloride in whole fish to 400 for perchloroethylene in liver, followed by very rapid loss after exposure ceased [6, 43]. No evidence for metabolism has been found but the possibility should certainly not be excluded. 

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