Also chlorinated solvents

Chlorofluorocarbon (CFC) solvents (cleaning) Solvents containing chlorine and fluorine. Used in removing non-polar contaminants such as oils. Effective solvents but regulated because of health and environmental concerns. Examples CFC-11 (CCI3F) CFC-12 (CCI2F2) CFC-113 (CF2CICFCI2). See also Chlorinated solvents Hydrochlorofluorocarbon (HCFC) solvents. 

Uses. Tetrahydrofurfuryl alcohol is of interest in chemical and related industries where low toxicity and minimal environmental impact are important (134). For many years tetrahydrofurfuryl alcohol has been used as a specialty organic solvent. The fastest growing appHcations are in formulations for cleaners (135) and paint strippers (136), often as a replacement for chlorinated solvents (137). Other major appHcations include formulations for crop sprays, water-based paints, and the dyeing and finishing of textiles and leathers. Tetrahydrofurfuryl alcohol also finds appHcation as an intermediate in pharmaceutical appHcations. 

Acetonitrile also is used as a catalyst and as an ingredient in transition-metal complex catalysts (35,36). There are many uses for it in the photographic industry and for the extraction and refining of copper and by-product ammonium sulfate (37—39). It also is used for dyeing textiles and in coating compositions (40,41). It is an effective stabilizer for chlorinated solvents, particularly in the presence of aluminum, and it has some appflcation in... 

Uses. 3-Pentenenitrile, 3PN, is used entirely by the manufacturers to make adiponitrile. i7j -2-Pentenenitrile, 2PN, can be cycli2ed catalyticaHy at high temperature to produce pyndine, a solvent and agncultural chemical intermediate. 2PN is also chlorinated to manufacture pentachloropyndine, an intermediate in the insecticide Dursban produced by Dow. Addition of ammonia to 2PN foUowed by reduction leads to 1,3-pentadiamine (Dytek ep), which is used as a curing agent for epoxy coatings and as a chain modifier in polyurethanes. 

Calcium carbide has been used in steel production to lower sulfur emissions when coke with high sulfur content is used. The principal use of carbide remains hydrolysis for acetylene (C2H2) production. Acetylene is widely used as a welding gas, and is also a versatile intermediate for the synthesis of many organic chemicals. Approximately 450,000 t of acetylene were used aimuaHy in the early 1960s for the production of such chemicals as acrylonitrile, acrylates, chlorinated solvents, chloroprene, vinyl acetate, and vinyl chloride. Since then, petroleum-derived olefins have replaced acetylene in these uses. 

Of the estimated 710,000 t consumed in 1990, 25% was used to produce vinyl chloride [75-01-4] monomer (VCM), 14% for vinyl acetate [108-05-4] monomer (VAM), 23% for butanediol, 14% for industrial use, and the balance to produce other products such as acryUc acid, synthetic mbber, chlorinated solvents, and acetylene black. The demand for PVC is expected to decrease as legislation limiting its use in packaging is pending. Consequentiy, VCM consumption will also suffer. 

The physical properties of methylene chloride are Hsted in Table 1 and the binary a2eotropes in Table 2. Methylene chloride is a volatile Hquid. Although methylene chloride is only slightly soluble in water, it is completely miscible with other grades of chlorinated solvents, diethyl ether, and ethyl alcohol. It dissolves in most other common organic solvents. Methylene chloride is also an excellent solvent for many resins, waxes, and fats, and hence is well suited to a wide variety of industrial uses. Methylene chloride alone exhibits no dash or fire point. However, as Htde as 10 vol % acetone or methyl alcohol is capable of producing a dash point. 

Further dechlorination may occur with the formation of substituted diphenyhnethanes. If enough aluminum metal is present, the Friedel-Crafts reactions involved may generate considerable heat and smoke and substantial amounts of hydrogen chloride, which reacts with more aluminum metal, rapidly forming AlCl. The addition of an epoxide inhibits the initiation of this reaction by consuming HCl. Alkali, alkaline-earth, magnesium, and zinc metals also present a potential reactivity hazard with chlorinated solvents such as methylene chloride. 

Tetrachloroethane [79-34-5] acetylene tetrachloride, CHCI2CHCI2, is a heavy, nonflammable Hquid with a sweetish odor. It is miscible with the chlorinated solvents and shows high solvency for a number of natural organic materials. It is also a solvent for sulfur and a number of inorganic compounds, eg, sodium sulfite. 

Dichloroethylene can be used as a low temperature extraction solvent for organic materials such as dyes, perfumes, lacquers, and thermoplastics (13—15). It is also used as a chemical intermediate in the synthesis of other chlorinated solvents and compounds (2). 

Emulsion cleaners These are emulsified chlorinated solvents and are kerosene based, suitable for mineral oils (petroleum and heavy petroleum greases) and deep-drawn components, using lead compounds as lubricants. They are also suitable for non-ferrous metals. 

Most of the byproduct HCl is used captively, primarily in oxyhydrochlorination processes for making vinyl chloride and chlorinated solvents or for Mg processing (p, 110), The scale of the industry is enormous for example, 5,2 million tonnes of HCl per annum in the US alone (1993), HCl gas for industrial use can be transmitted without difficult over moderate distances in mild-steel piping or in tank cars or trailers. It is also available in cylinders of varying size down to laboratory scale lecture bottles containing 225 g. Aqueous hydrochloric acid consumption (1993) was 1,57 Mt (100% basis). Price for anhydrous HCl is 330/tonne and for 31,4% aqueous acid 73/tonne (1993) depending on plant location and amount required. 

Much of the CI2O manufactured industrially is used to make hypochlorites, particularly Ca(OCl)2, and it is an effective bleach for wood-pulp and textiles. CI2O is also used to prepare chloroisocyanurates (p. 324) and chlorinated solvents (via mixed chain reactions in which Cl and OCl are the chain-propagating species).Its reactions with inorganic reagents are summarized in the scheme opposite. 

Butylene oxide may be hydrolyzed to butylene glycol, which is used to make plasticizers. 1,2-Butylene oxide is a stabilizer for chlorinated solvents and also an intermediate in organic synthesis such as in surfactants and pharmaceuticals. 

Several of the commercially available 16,000 chlorinated and brominated compounds have already been regulated or harmed, CFCs, DDT and chlorinated biphenyls are typical examples. Many others are being phased out according to the Montreal Protocol on Substances that Deplete the Ozone Layer. This includes chlorinated solvents, methyl bromide and halons (e.g. CF3Br). The milder ozone destroyers, hydrochlorofluorocarbons (HCFCs) will also, eventually, be phased out. 

The results of chain transfer studies with different polymer radicals are compared in Table XIV. Chain transfer constants with hydrocarbon solvents are consistently a little greater for methyl methacrylate radicals than for styrene radicals. The methyl methacrylate chain radical is far less effective in the removal of chlorine from chlorinated solvents, however. Vinyl acetate chains are much more susceptible to chain transfer than are either of the other two polymer radicals. As will appear later, the propagation constants kp for styrene, methyl methacrylate, and vinyl acetate are in the approximate ratio 1 2 20. It follows from the transfer constants with toluene, that the rate constants ktr,s for the removal of benzylic hydrogen by the respective chain radicals are in the ratio 1 3.5 6000. Chain transfer studies offer a convenient means for comparing radical reactivities, provided the absolute propagation constants also are known. 

Synthetic rubbers are also used for particular applications. Hypalon (trademark, E. I. du Pont de Nemours) has a good resistance to strongly oxidising chemicals and can be used with nitric acid. It is unsuitable for use with chlorinated solvents. Viton (trademark, E. I. du Pont de Nemours) has a better resistance to solvents, including chlorinated solvents, than other rubbers. Both Hypalon and Viton are expensive, compared with other synthetic, and natural, rubbers. 

U.S. EPA published a guide about the steps needed to understand the rate and extent to which natural processes are reducing contaminant concentrations.56 Although this guide is directed at sites contaminated by chlorinated solvents, some of the steps would also have relevance for sites contaminated by oxygenates like MTBE. The guide identifies parameters that are useful in the evaluation of natural attenuation and provides recommendations on how to analyze and interpret the data... 

Anaerobic demetalation of Mg[pz(/V-Mc2)8 gives only the free base pz, H2[pz(7V-Me2)8] 101 (TFA, 21% and AcOH, 69% yield, respectively). Slow oxidation of aminoporphyrazines also occurs when solutions are left standing for prolonged times in chlorinated solvents CH2C12 and CHC13 while no oxidation is observed in polar solvents such as DMF and pyridine. 

For this library, we chose to use three types of isocyanates (neutral, electron rich, and electron deficient) to demonstrate the broad utility of the urea-formation reactions. Employing the above strategy and using the split-and-pool approach, we synthesized a 27-membered urea library with purities ranging from 95 to 99%. All the compounds prepared were characterized by 1FI NMR and mass spectroscopy. Acetonitrile can also be used as a substitute for DCM, but lower yields and product purities are generally observed. Attempts to use other protic solvents, such as isopropyl and ethyl alcohol, were unsuccessful. The best results were achieved when a chlorinated solvent (DCM) was used. The structure identity of all products was confirmed by 1FI NMR and MS spectroscopy. Expected molecular ions (M + Na+) were observed for all the products, and in all cases as the base peak. The compounds and yields are listed in Appendix 3.1. 

The nature of the solvent also determines the chemoselective outcome in the reaction products. Products arising from the incorporation of one solvent molecule are formed (besides dibromides) in alcohols, acetic acid and acetonitrile (Id-e), whereas dibromo derivatives are formed exclusively in chlorinated solvents, nitromethane and in ionic liquids. (9) Chemoselectivity depends on the relative nucleophilicity of the solvent and the counterion, although it is affected also by other phenomena (ion pairing, and ion dissociation) in methanol the addition process gives quasi-exclusively bromo-methoxy adducts, whereas in acetic acid dibromides are the main products, formed in addition to smaller amounts of the bromo-acetoxy derivatives. (70)... 

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