Section 4 Chlorinated solvents

Chief the incident command system title for individuals responsible for manag ent of functional sections operations, planning, logistics, finance/administration, and intelligence/investi-gations, if established as a separate section Chlorinated solvent organic solvent that contains chlorine atoms... 

Palmer AN (1996) Rates of limestone dissolution and calcite precipitation in cave streams of east-central New York state, northern section. Geol Soc Am 28 89 Parker BL, Cherry JA, Chapman SW, Guilbeault MA (2003) Review and analysis of chlorinated solvent dense nonaqueous phase liquid distribution in five sandy aquifers. Vadose Zone J 2 116-137... 

If 2, 3 -0-benzylideneuridine is treated with N-bromosuccinimide in a chlorinated solvent, in the absence of triphenylphosphine, the product is 3 -0-benzoyl-2, 5-dibromo-2 deoxyuridine (see Section II,4 p,276). 

McCarty, P. L. Semprini, L. (1993). Ground water treatment for chlorinated solvents. In In Situ Bioremediation of Ground Water and Geological Material A Review of Technologies, ed. R. D. Norris etal. EPA/600/R-93/124. Section 3.NTIS Document No. PB93-213364, Washington DC. 

A general kinetic model should accommodate all chemical processes known to affect the dechlorination process. These include (1) reductive dechlorination takes place on the iron surface, rather than in the aqueous phase, so adsorption must occur (2) other components in the system may affect the dechlorination reaction by competing for the reaction sites (3) surface sites for reduction and for sorption may not be the same, as for the system with PCE and TCE where dechlorination takes place on the reactive sites, but most of the adsorption is clearly on the nonreactive sites (Burris et al., 1995). In the following section we will first discuss a single-site model similar to the one used by Johnson et al. (1998), which has accounted for the first two observations, then develop a two-site model that will also take the third observation into consideration. We aim to illustrate how coadsorbates in the iron system will affect adsorption and reduction of chlorinated solvents. TCE will be used as an example since relevant adsorption and reduction data are available, from which the required parameters for simulation could be estimated. 

In summary, phase behavior was very sensitive to oil hydrophobicity. Systems that work for hydrophilic NAPLs such as chlorinated solvents will not necessarily work for more hydrophobic NAPLs, and surfactant systems that work for slightly hydrophobic NAPLs (e.g., dodecane) do not necessarily work for more hydrophobic NAPLs such as hexadecane. These results thus point to the need to characterize the NAPL hydrophobicity (EACN), as discussed in the previous section, and design the surfactant system appropriately. 

Polychlorinated biphenyls (PCBs) are mixtures of biphenyls with 1 to 10 chlorine atoms per molecule. They are oily fluids with high boiling points, great chemical resistance, and low electrical conductivity, and have been used as plasticizers in polyvinyl polymers, insulators and coolants in transformers and heat exchange fluids. Dioxins and furans (see Section 9.1) are not produced intentionally but are derived from combustion processes of chlorinated aromatic hydrocarbons, pesticides and chlorinated solvents. 

Chlorine and sodium hydroxide production by the electrolysis of brine solutions necessarily locks the ratio of the two products to the theoretical ratio of the process [45, 46]. When the market for sodium hydroxide exceeds the market for chlorine, the causticization of sodium carbonate to sodium hydroxide (Section 7.3) may be used by some suppliers and consumers to supplement the available sodium hydroxide without producing large amounts of excess chlorine. Another expedient for large-scale chloralkali producers faced with this situation is to stimulate the chlorinated solvent or hydrochloric acid markets in an attempt to increase the consumption of chlorine to restore the balance. These measures are not usually rapid enough to respond over the short term unless the solvent plant is also operated by the chloralkali producer. 

Downside reports a yes score has been awarded. Two fires and eight releases concerning four German plants are reported on in the CER under the section titled Environmental Incidents , and there is an article describing the work being carried out on land remediation at Berghausen, where over 1200 tonnes of chlorinated solvents have been extracted from the soil. 

Further papers in this section report intramolecular hydrogen-bonding in 2-arylaminomethylenecycloalkanones (menthone, carvomenthone, camphor)," the effect of chlorinated solvents on the stability constants of hydrogen-bonded complexes between pyrrole and, inter alia, fenchone,and a correlation of half-wave oxidation potentials with the pK values of the corresponding conjugate acids e.g. 3-endo-cyanocamphor). ... 

Chlorinated Solvents. Ortho-dichlorobenzene or similar compounds are used in a modified form of the baking process for sulfonating aromatic amines, as discussed in a preceding section. They are high-boiling, relatively inert, inexpensive, and are immiscible with water, thereby facilitating removal of the latter from the reaction mixture by partial-pressure distillation. 

THEODORE E. TABOR Is a native of Montana, where he obtained a B.A. degree In chemistry from the University of Montana-Mlssoula. He was a National Defense Education Act fellow at Kansas State University, where he obtained his Ph.D. degree In chemistry. He Joined the Dow Chemical Company In Midland, Mich., and has held various positions In Dow s R D organization, a part of corporate R D. His research areas Include organic reaction mechanisms, applications of chlorinated solvents In textile processing, and the development of flame retardants for textiles and plastics. He Is a member of the ACS and has held numerous positions In the Midland Section, Including the chairmanship of the section. 

The types of biodegradation reaetions that have been observed for different chlorinated solvents are presented in Table 23.1.4. The remainder of this section will focus on... 

Figure 23.1.12. Hydrogeologic section, Plattsburg Air Force Base, New York. [From T.H. Wiedemeier, H. S. Rifai, C. J. Newell and J.T. Wilson, Natural Attenuation of Fuels and Chlorinated Solvents in the Subsurface, after reference 88. Copyright 1999 John Wiley Sons, Inc. Reprinted by permission of John Wiley Sons, Inc.]...

Whereas aromatic hydrocarbons (especially the higher molecular weight materials) have high POCP and MIR values, many of the common esters and alcohols have lower values. Chlorinated solvents, because they are very unreactive, do not react significantly with nitrogen monoxide and therefore generally have very low POCP values (see section 6.2.1). Some of the natural VOCs (e.g. terpenes and limonene) have high POCP values. 

Two models BIOCHLOR and RT3D for the natural attenuation of chlorinated solvents have been presented recently in the general literature and will be briefly discussed in this section. 

Chlorinated solvents, on the other hand, although nonflammable, are relatively toxic and contribute to pollution. In addition, they may leave chloride residues on the metal surface that can later initiate corrosive attack. They are used largely for vapor degreasing (tri- or perchlorethylene), in which the work is suspended in the vapor of the boiling solvent. Care must be exercised in the vapor degreasing of aluminum, ensuring that adequate chemical inhibitors are added and maintained in the chlorinated solvent in order to avoid catastrophic corrosion (see Section 21.1.4.1) or, in the extreme, to avoid an explosive reaction. 

Some classes of solvents are inherently unstable. Final breakdown products and/or intermediates may themselves be chemically reactive or alter the chromatographic properties of the solvent enough to be a cause of concern to the analyst. To further illustrate this, two classes of solvents (ethers and chlorinated solvents) and acetone will be discussed. Ethanol, due to its highly regulated status in its neat (or 200 proof) form, is often available in a denatured ft>rm. There are many denaturants for ethanol and they will be presented in this section. Finally, problems associated with water will be considered with regard to the pluses and minuses of manufactured versus inhouse-produced sourcing. 

It is known that dissolving chlorine in water leads to a solution that contains hypochlorous acid (HOCl) and bromine dissolved in water contains hypobromous acid (HOBr). In one experiment, 1-pentene is mixed with chlorine and water (HOCl in aqueous media) and the major product is l-chloro-2-pentanol (48), in 43% isolated yield. ° In the previous section, chlorine reacted with 1-pentene in a nonaqueous solvent such as carbon tetrachloride to give a dichloride. To ascertain why this reaction is different, the first useful observation is that HOCl is in solution rather than Cl-Cl. The polarization of HOCl is HO -Cl, where chlorine is the electrophilic atom. The 7t-bond of an alkene should react with the positive chlorine atom, and cleavage of the Cl-H bond will give hydroxide ion, which is a... 

The chemical properties of cast polyurethane elastomers are similar to those of flexible foams (Section 14.5.1.2). Of particular importance is the outstanding resistance to aliphatic hydrocarbon fuels and oils and to oxygen and ozone these properties make the elastomers useful as seals. Aromatic and chlorinated solvents cause some swelling. 

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