Poly chlorinated biphenyls

Poly Chlorinated Biphenyls. The photoconductivity detector provides good responses for polychlorinated biphenyls separated by GPC. The normal matrix components are detected by RI and UV detectors while the polychlorinated species show high responses in the electrochemical detector (Figure 8). ... 

PCBs and PCDDs. In Diarylide Yellow manufacture, the use of formate buffer to enhance pigment transparency for offset ink was discontinued in the nineteen seventies, when it was realized that polychlorinated biphenyls were being produced as an undesirable by-product of the coupling reaction. In Phthalocyanine Blue crude synthesis, the commonly used solvent, trichlorobenzene, was also discontinued in the US, as a potential source of poly-chlorinated biphenyls. More recently, use of chloranil, manufactured from chlorinated phenols, has been discontinued in the synthesis of dioxazine violet crude and sulfonated dioxazine acid dyes, so as to minimize by-product formation of polychlorinated dibenzodioxins and dibenzofurans (PCDDs/PCDFs). A new grade ofhigh purity chloranil is now produced from hydroquinone for dye and pigment manufacture. 

Figure 1.2 Overview of the EPA s organics protocol. VOCs, volatile organics SVOCs, semivolatile organics OCs/PCBs, organochlorine pesticides/poly-chlorinated biphenyls HS-GC-FID, static headspace coupled to gas chromatography and flame ionization detection LLE, liquid-liquid extraction LSE, liquid-solvent extraction or solvent leaching from solid matrices GC-ECD, gas chromatography and electron-capture detection GC-MS, gas chromatography and mass spectrometry RP-SPE, reversed-phase solid-phase extraction.

Poly Chlorinated Biphenyls (PCBs) are dielectric liquids which have been widely used in various industries for more than 50 years because of their supposed nonflammability and their chemical inertness. Recent accidents all over the world have shown PCBs can burn and their combustion byproducts (dioxines, furanes, etc.) are highly toxic. In fact, confusion has been created in the public mind between the dangers and hazards induced by PCBs themselves and those generated by their byproducts. Meanwhile, PCB pollution and toxicity is a major concern for regulating agencies, such as EPA in the United States and industry. Most Western countries now ban PCB production and strictly control their use. However, enormous amounts of PCB remain in use and their safe handling, destruction and replacement are heavy burdens for industrial users. 

Kannan, K., Kajimara, N., Le Boeuf B.J., and Tanabe, S. (2004) Organochlorine pesticides and poly-chlorinated biphenyls in California sea lions. Environ. Pollut., 131, 425—434. 

The residue can be minimized using bilayer schemes and sensitivity can be increased by either using poly(vinyl biphenyl) derivatives that are more absorbing at 248 nm or by adding anthracene derivatives to chlorinated poly(styrene) polymer. The present formulations are not production worthy because of this residue and we are currently working on approaches that may eliminate this problem. 

Osaki,K., Sakato.K., Fukatsu,M., Kurata,M., Matusita,K., Tamura,M. Normal stress effect in dilute polymer solutions. III. Monodisperse poly-a-methylstyrene in chlorinated biphenyl. J. Phys. Chem. 74,1752-1756 (1970). 

When the additive consisted of an Aroclor (a chlorinated biphenyl or terphenyl), a poly(styrene glycol), or an abietic acid derivative, the tensile moduli of the films increased as the concentration of additive was increased to about 30%. In two films (from the bisphenol I and bisphenol A polymers), the modulus increased as the concentration of a chlorinated terphenyl increased even to 40%. Instead of becoming more flexible, as would be expected, the films became stiffen Most of these additives, incidentally, were viscous or very viscous oils. The effect of two Aroclors on the tensile moduli is shown in Figure 1. 

Hesso A, Hameila M, Tomaeus J. 1992. Poly chlorinated dioxins, fiirans and non-ortho polychlorinated biphenyls in blood of exposed laboratory personnel. Chemosphere 25 1053-1059. 

The reductive photodehalogenation of aryl halides has been actively investigated in recent years. Special attention has been given to (poly)halobenzenes and (poly)halo-biphenyls. The reactions are of interest in view of their mechanisms, and because of the importance of chlorinated aromatic hydrocarbons as environmental pollutants and the possibility of their photoinduced degradation. The photochemistry of aryl halides and related compounds in general14 and the photochemistry of polyhaloarenes in particular18 have been reviewed. 

Poly-QM obtained by the use of the vapor-coating process is readily soluble in chlorinated biphenyls and benzyl benzonate at 300 °C and highly crystalline. The... 

FIG. 16.17 Power law exponent — ft — 1 — n as a function of the coil overlap parameter c[ 7], for solutions of polystyrene (filled symbols) and poly(a-methyl styrene) in chlorinated biphenyls (open symbols). The values of [77] were obtained in toluene. Molecular weights range from 860 to 13,600 kg/mol for polystyrene and from 440 to 7500 kg/mol for poly(a-methyl styrene). From Graessley (1974). Courtesy Springer Verlag. 

Solid-phase microextraction (SPME) — is a procedure originally developed for sample preconcentration in gas chromatography (GC). In this procedure a small-diameter fused silica optical fiber, coated with a liquid polymer phase such as poly(dimethylsiloxane), is immersed in an aqueous sample solution. The -> analytes partition into the polymer phase and are then thermally desorbed in the GC injector on the column. The same polymer coating is used as a stationary phase of capillary GC columns. The extraction is a non-exhaustive liquid-liquid extraction with the convenience that the organic phase is attached to the fiber. This fiber is contained in a syringe, which protects it and simplifies introduction of the fiber into a GC injector. Both uncoated and coated fibers with films of different GC stationary phases can be used. SPME can be successfully applied to the analysis of volatile chlorinated organic compounds, such as chlorinated organic solvents and substituted benzenes as well as nonvolatile chlorinated biphenyls. 

Farwell and coworkers [209,210] investigated the electrochemistry of mono- and poly-chlorobiphenyls at mercury in DMSO containing TEABr. These compounds exhibit sequential two-electron removal of chlorine, but there is a tendency (due to the varied pattern of chlorine substitution) for more than one product to be formed sometimes two chlorines are expelled simultaneously. In another study, Maruyama and Murakami [211] reported that chlorinated biphenyls are reduced in DMF via one-electron cleavage of a carbon-chlorine bond to yield chloride and an aryl radical, which subsequently abstracts a hydrogen atom from the solvent. Rusling and Arena [212] probed the reduction of 4-bromo-, 4,4 -dibromo-, 3,4-dichloro-, and 2,2, 5,5 -tetrachlorobiphenyl at mercury in... 

Zhao X, Zheng M, Zhang B, et al. Evidence for the transfer of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and poly chlorinated dibenzofurans from soils to biota. Sci Total Environ 2006 368(2-3) 744-52. 

Polychlorinated biphenyls (PCBs), the ultimate (poly)chlorinated solvents are 2 membered ring compounds that when heated to 270 produce dibenzofurans (DBFs) that are 1,000 or more times as neurotoxic.Initial evaluations were of a few PCB exposed individuals and 14 firemen exposed to DBFs who showed severe impairment measmed after a medical schools power plant transformers cooked and exploded. Most of the firemen could not pass the physical, balance and truck driving requirements to return to duty and were retired on disability. ... 

Several different types of poly(metal phosphinates) have been described over the past few years (J2,13). One that contains a trivalent octahedral metal atom was synthesized by reaction (IX-34) and some subsequent variations of it 10, II, 17, 22, 110). Reaction of a monomeric chelate with substituted phos-phinic acids in bulk or in solution in an inert atmosphere gave polymer (//, 22). Temperatures of 170°-250°C and solvents such as biphenyl and chlorinated biphenyls were used. Other monomeric ligands such as 2-picolinic acid could be used in place of acetylacetone, but polymer formation was more difficult 119). 

Fig. 35. Dissipation factor vs frequency for polar polymers at 25°C. A, Clear cast phenolic B, plasticized PVC C, poly(vinyl chloride-co-vinylidene chloride) (saran) D, unplasticized PVC E, poly(methyl methacrylate) G, poly(hexamethylene adipamide) (nylon) H, poly(2-chlorobutadiene) I, plasticized ethyl cellulose J, cast epoxy K, methyl silicone rubber L, polyurethane foam (d = 33 g/L) and M, 50% polystyrene-50% chlorinated biphenyl.

PAH PAJ PAO PCBs Polyaromatic hydrocarbons. Petroleum Association of Japan. Poly-a-olefin base stock of various viscosity classifications. Any of the chlorinated derivatives of biphenyl (also called diphenyl). 

However, the use of perchlorates in pyrotechnic formulations is discouraged due to the supposed toxicity of this chemical which has been linked to causing thyroid disorders. Furthermore, the combustion of polychlorinated organic materials such as poly(vinyl) chloride has been shown to produce polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). These polychlorinated chemicals are highly toxic and are potent carcinogens. Therefore, the removal of perchlorates and chlorinated organic materials in pyrotechnic formulations would eliminate the formation of these aforementioned pollutants. 

When Aroclor 1268 (a commercial PCB fraction that contains a mixture of CI7, Clg, CI9, and Cl 10 poly chi oro-biphenyls) is combined with excess 02 -, the entire mixture is degraded. Samples taken during the course of the reaction confirm that (a) the most heavily chlorinated members react first (the initial nucleophilic addition is the ratedetermining step) and (b) all components are completely dehalogenated. Tests with other PCB mixtures establish that those components with three or more chlorine atoms per phenyl ring are completely degraded by 02, within several hours. 

Matsuzawa et al. [12] studied the removal of different aromatic chemicals as model HOCs from aqueous solutions by sorption onto commercial BDPs as the sorbents, such as PLA, poly(e-caprolactone) (PCL), poly(butylene succinate) (PBS), poly(butylene adipate/terephthalate) (PBT), poly (3-hydroxybutyrate) (PHB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The target HOCs used were biphenyl (BP), bisphenol A (BPA), dibenzofuran (DF), diethylstilbestrol (DES), nonylphenol (NP), phenol, and its chlorinated derivatives, 2-monochlorophenol (2-CP) and 3,5-dichlorophenol (3,5-DCP). They found that all of the BDPs tested, except PLA, adsorbed the aromatic compounds effectively at a removal efficiency of more than 98% at ambient temperature (Table 30.1). When aqueous solutions of phenol and its chlorinated derivatives were treated with BDPs, the removal efficiency increased with increasing number of chlorine substituents on phenol. On the other hand, the chlorophenols were not removed by PLA under the experimental conditions used. 

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