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In this study, Fe/Fe3O4 mixture was first applied as an additive to achieve the highly-effective mechanochemical destruction (MCD) of two halogenated organic pollutants (HOPs), hexachloroethane (HCE) and hexachlorobenzene (HCB). The MCD of HCE was more effective than that of HCB in virtue of the lower dissociation energy of CCl bond. The MCD of HOPs occurred mainly via the reduction by Fe, Fe3O4 and Fe/Fe3O4. The oxidation of Fe3O4 and reduction of FeO (formed on account of the oxidation of Fe by oxygen-containing species) may also contribute to the HOP destruction. Fe/Fe3O4 mixture exhibited a higher dechlorination rate (DR) than other three effective additives (i.e., Fe/SiO2, Al/Al2O3 and Mg/Al2O3 mixture), owing to the electrical property of Fe3O4 and its electron transfer with Fe. The HOP destruction was significantly impacted by the mass fraction of Fe3O4 (MFmag) and achieved the maximum level with an MFmag of 70%. The DR of HOPs in the atmosphere of air was higher than those of pure oxygen and nitrogen because of the oxygen vacancy in Fe3O4 and oxidation of Fe. The presence of water dramatically inhibited the HOP destruction due to the decrease of collision energy and its competition for the active sites in both Fe and Fe3O4. As expected, the DR of HOPs increased with rotation speed, and the mass ratio of ball to reactant and additive to pollutant. The analysis of intermediates indicates that HCB destruction was mainly via dechlorination and polymerization, while HCl cleavage also played an important role in HCE destruction. The results demonstrate that Fe/Fe3O4 mixture is a suitable additive for MCD process.

The catalytic performance of iron oxides in 2,4,4′-trichlobiphenyl (PCB28) degradation following an order of goethite > magnetite > hydrated iron(III) oxide > hematite was observed in four iron oxides catalyzed Fenton-like reactions, which was not consistent with the stoichiometric efficiency of OH generation. This result indicates that OH was not the sole active species responsible for PCB28 degradation in four iron oxides catalyzed Fenton-like systems. The reductive degradation of hexachloroethane (HCE) was 76.8%, 58.7%, 46.1% and 37.6% for magnetite, goethite, hematite and hydrated iron(III) oxide, respectively, further suggesting that both oxidative species ( OH) and reductive species (HO2 ) simultaneously contributed on PCB28 degradation. The addition of tert-butyl alcohol ( OH scavenger) decreased the amount of 7-hydroxycoumarin (7-HC, OH indicator) by 42%, 77%, 97%, and 97% for magnetite, goethite, hematite, and hydrated iron(III) oxide, respectively. Meanwhile, the addition of p-benzoquinone (HO2 scavenger) only reduced the amount of 7-HC by 77%, 27%, and 33.5% for magnetite, hematite, and hydrated iron(III) oxide, respectively; but increased the amount of 7-HC by 126.7% in the goethite/H2O2 system. This result indicates that the mechanism of OH generation from H2O2 catalyzed by four iron oxides was different. For goethite, the surface lattice iron was primarily responsible for activating H2O2 to form reactive species ( OH and HO2 ) and thereby degrade pollutants on the oxide surface. For magnetite, both the surface lattice iron and the dissolved Fe in solution played an equally important role in catalyzing H2O2 decomposition to form and propagate reactive species for pollutant degradation. For hematite and hydrated iron(III) oxide, the solution phase chain reaction effectively propagated by dissolved Fe should be the primary catalytic mechanism although the chain reaction was initiated by the surface processes.

The degradation of hexachloroethane using chloridobis(dimethylglyoximato)pyridinecobalt(III), chloridobis(methylphenylglyoximato)pyridinecobalt(III) and chloridobis(diphenylglyoximato)pyridinecobalt(III) is described. To achieve the degradation, the cobalt complexes were reduced to the Co(I) oxidation state by electrochemical means. The chemical catalysis was studied using cyclic voltammetry by monitoring the current increase near the Co(II)/Co(I) reduction potential as the concentration of organohalogen was increased in solution. Tetrachloroethene was found as the degradation product. The apparent rate constant for the dehalogenation of hexachloroethane was estimated for all cobaloximes, obtaining 2.54 ± 0.08 × 105 for [Co(dmgH)2Cl(py)]; 2.38 ± 0.06 × 105 for [Co(mpgH)2Cl(py)] and 2.79 ± 0.15 × 105 for [Co(dpgH)2Cl(py)].

Traditional Fermi resonance is a vibrational mixing between a fundamental and a combinational or overtone mode. What will happen when the resonance occurs between a generated fundamental and an overtone mode? In this report, we performed a high pressure Raman spectroscopic investigation on hexachloroethane up to 20 GPa. The origin of the triple bands at 841, 851 and 860 cm −1 were thoroughly discussed, and their intensity evolution in the compression process are further analyzed. The triple bands can be attributed to the quantum mixing between generated v 7 fundamental mode and the v 2 overtone mode, This intriguing spectral phenomenon is named as double Fermi resonance, and a new mechanism of the interaction of double Fermi resonance is proposed. Pressure provides us a new strategy not only for the mode assignments but also to understand the mechanism underlying the vibrational mixing.

Inorganica chimica acta, 520, ISSN:0020-1693, ISSN:1873-3255

A total of 152 groundwater samples were collected around a contaminated site to evaluate the carcinogenic and noncarcinogenic risks of exposure to twelve volatile chlorinated hydrocarbons (VCHs) by oral ingestion, dermal contact and inhalation absorption during showering. Although toxicity data of some VCHs are fragmentary, the results showed that the carcinogenic and noncarcinogenic risks of exposure to VCHs in contaminated drinking groundwater for local residents needs immediate attention. The main risk contributors for the carcinogenic and noncarcinogenic risks are carbon tetrachloride and 1,1,2-trichloroethane through inhalation exposure pathway, respectively. The health risk contribution rates associated with three exposure pathways for a specific VCH were intrinsic to the compound, and the dermal contact corresponded to a negligible contribution for almost every VCH species. Although most of the evaluated VCHs had a higher risk contribution by inhalation than by oral ingestion pathway, the integrated multi-VCH health risk contributions of the three exposure pathways were mainly dependent on the VCH compositions. Drinking boiled water not only decreased the exposure risk but also affected the risk contribution rates of three exposure pathways, which indicates that it is feasible to reduce the risk of VCH exposure during daily activities based on the risk contribution of the exposure pathways. In addition to the VCHs included in the drinking water standards, species such as 1,1,2,2-tetrachloroethane and hexachloroethane also showed a remarkable exposure health risk according to the standardized health risk calculation, which implied that improved drinking water standards are urgently required.

Methanol and 2-propanol solutions of 1,2-dibromotetrafluoroethane and 1,1,2-trichlorotrifluoroethane were irradiated with γ-rays after perfect de-oxygenation. The product, formed by the substitution of one of the bromine or chlorine atoms with a hydrogen atom, was observed by radiation-induced degradation and the product was also de-halogenated. The G -value of de-halogenation was more than a thousand times higher than G (e solv − ) and increased with the decreasing dose rate, meaning that a chain reaction is involved in the process. The efficiency of the degradation in 2-propanol was several times higher than that in methanol. It is concluded that the charge transfer from an alcohol radical will be the trigger of the chain reaction the same as in the degradation of hexachloroethane in alcohol solutions ( Sawai et al., 1978 ).

a b s t r a c t Negative ion formation through dissociative electron attachment to the gas-phase volatile anaesthetics enflurane and isoflurane (C3H2ClF5O) and to two chlorinated ethanes, pentachloroethane (C2HCl5) and hexachloroethane (C2Cl6), have been studied in a crossed electron-molecular beam two sector field mass spectrometer experiment. Anion efficiency curves for the negatively charged fragments have been mea- sured over an electron energy range of approximately 0-17 eV, with an energy resolution of ∼1 eV. For the chlorinated ethanes, resonance features were generally found at ∼0 eV and at 7.5 eV. For the volatile anaesthetics, no zero energy resonances were observed. Instead, product anions were detected mainly in the 2-3 eV and 9 eV energy regions, with the exception of Cl − , whose dominant resonance occurs at approximately 0.6 eV and 0.9 eV for isoflurane and enflurane, respectively. To aid in the interpretation of the experimental results, quantum chemical calculations providing thermochemical thresholds of anion formation are also presented.

The main objective of this study was to test the capability of CNMs to mediate the reductive dechlorination of chlorinated aliphatic hydrocarbons. We herein investigated the mediation effects of graphene oxide (GO) and multi-walled carbon nanotubes (CNT) on the reductive dechlorination of hexachloroethane by sodium sulfide in aqueous solutions (pH buffered). The presence of 10 mg/L CNT or GO enhanced the observed pseudo-first-order rate constant ( k obs ) of the reaction by a factor of 2 and 4, respectively; the enhancement effects were significantly greater than that of a soil humic acid (20 mg C/L). The strong enhancement effects of the test CNMs were attributable to the facilitated electron transfer by the graphitic surfaces and particularly to the activation of C–Cl bonds of hexachloroethane by the zigzag carbon atoms at the edges and defects of the carbon nanomaterials. Additionally, changes of pH and the presence of dissolved humic acid could significantly affect the CNT- and GO-mediated reactions. The reaction rate was markedly accelerated by the increase of pH, but was suppressed by the coexisting dissolved humic acid. The findings imply that CNMs have the potential to enhance reductive dechlorination of relatively recalcitrant contaminants, such as chlorinated aliphatic hydrocarbons, in natural aquatic environments.

Lithiation of ferrocene with KOtBu and tBuLi in tetrahydrofuran at −78 °C, followed by treatment with hexachloroethane gives monochloroferrocene 1 in essentially quantitative yield. Lithiation of 1 with 1.2 equiv. lithium tetramethylpiperidide (LiTMP) in THF and chlorination with C2Cl6 gives 1,2-dichloroferrocene 2 contaminated with 1 and ferrocene. Treatment of this mixture with a tenfold excess of LiTMP and C2Cl6 yields after workup 1,2,3,4,5-pentachloroferrocene 3 in 29% yield based on ferrocene. Alternatively, from this mixture of 1 and 2 1,2,3-trichloroferrocene 4 and 1,2,3,4-tetrachloroferrocene 5 can be prepared in a stepwise fashion with yields of 40% and 46%, respectively. The molecular structures of 2 and 4 have been determined by X-ray diffraction and prove the postulated regiochemistry.

The degradation of tetrachlorothene (PCE) and hexachloroethane (HCA) using Fe(II) and Fe(II)–citrate at different H 2 O 2 concentrations was studied to clarify the role of oxidation and reduction pathways in Fenton chemistry. The interactions between oxidative and reductive radicals, and the cyclic nature of the Fe(II)–Fe(III) ions make for a complex system that displays a suppression or enhancement of PCE or HCA degradation as the experimental conditions are varied. PCE degradation decreased, while HCA degradation increased, for larger H 2 O 2 concentration. The degradations of PCE and HCA were lower in vials where they were individually present compared to vials with the PCE–HCA mixture. Using Fe(II)–citrate instead of Fe(II) resulted in slower PCE and insignificant HCA degradation. These observations indicate that degradation efficiency losses arise from interactions between the oxidant and reductant radical moieties, and that the production of reduction radicals is only significant when the hydroxyl radical (OH ) production is rapid.

Two red phosphorus (RP)-based smokes (P60 and RPB), differing from each other mainly in RP content and in type of additive, were evaluated for in vitro cytotoxicity (cell viability by the trypan-blue exclusion method) and genotoxicity (comet assay) by exposing BEAS 2B human bronchial epithelial cells to the smokes in a laboratory-scale chamber for 5 min. The irritation potency of RPB smoke was studied in mice. A hexachloroethane-based smoke (HC/Zn/TNT) was used as a reference in the studies. A 5-min exposure of BEAS 2B cells to P60 smoke (1.1, 2.2 and 4.4 g/m(3), measured as H(3)PO(4)) did not induce any cytotoxic effects, while RPB smoke (1.3, 2.6 and 5.1g/m(3), measured as H(3)PO(4)) caused a mild decrease in cell viability at higher concentrations, without a clear dose-dependent effect. Neither of the RP smokes showed a genotoxic response in the comet assay with BEAS 2B cells, while HC/Zn/TNT was clearly genotoxic (0.9-3.5 g/m(3) as ZnCl(2)). In the mouse bioassay, head-only exposure to RPB smoke (20-450 mg/m(3) for 30 min as a single exposure, or 65-90 and 25-110 mg/m(3) - measured as H(3)PO(4) - for 30 min/day during 5 days) caused a concentration-dependent sensory irritation, which was evident as a decrease in respiratory rate and an increase in time-of-pause after inspiration, in a similar manner as with HC/Zn/TNT smoke. The concentration that caused a 50% decrease in respiratory frequency (RD(max)50) was calculated to be 1140 mg/m(3) for the RPB smoke and 145 mg/m(3) for the HC/Zn/TNT smoke. No pulmonary irritation was observed.

There has been no human epidemiological data regarding the hepatic injuries of hexachloroethane–zinc oxide (HC/ZnO) inhalation. This is the first epidemiological study to investigate whether HC/ZnO inhalation exposure can induce hepatic dysfunction in exposed soldiers. Twenty soldiers, exposed to high concentration of HC/ZnO smoke for 3–10 min in a narrow tunnel (0.6 m in width) during military training, were recruited as exposed group and they were divided into high-exposed group (n = 10) and low-exposed group (n = 10) by the distance from the explosion locale as a surrogate of exposure condition. Another 64 soldiers, not visiting the explosion areas, were recruited as referents. Venous blood was collected for liver function analyses. After log transformation of alanine aminotransferase (ALT) and adjustment for potential confounders, serum ALT in high-exposed soldiers was statistically significantly higher than those of referents for the 3 weeks following exposure. The serum ALT in low exposed soldiers was statistically significantly higher than those of referents at the 3rd week following exposure. The mean ALT levels also showed decreasing gradients by the distance from exposure locale. In addition, the proportions of abnormality on ALT (>40 U/L) were also significantly different among three exposure conditions. Follow-up study showed that the hepatic dysfunction started from 1 to 2 weeks and peaked from 3rd to 5th week after exposure. ALT level was then returned to normal within 6–8 weeks after removing from HC/ZnO smoke exposure. No sequelas in hepatic dysfunction were found until 72 weeks follow-up. Conclusion: We concluded that inhalation of HC/Zn smoke can induce acute, dose-dependent and definite temporal relationship hepatic dysfunction.

The paper describes the combustion synthesis of carbon materials from hexachloroethane (C2Cl6), hexachlorobenzene (C6Cl6), and a mixture of these compounds. The chemical composition (elemental analysis), structural composition (XRD, Raman spectroscopy), microstructure (SEM), surface physicochemical properties (low-temperature nitrogen adsorption, XPS, FTIR) and electrochemical behavior (cyclic voltammetry) of the solid reaction products were investigated. Their unique structural and surface properties depend on the chemical composition of the starting compounds. The properties of the carbon samples tested are much like those of carbon black, but the material from hexachloroethane exhibits the most distinctly amorphous features. In contrast, the adsorptive properties (porous structure) of the sample obtained from hexachlorobenzene tend to resemble those of activated carbon.

Two-dimensional exchange 35 Cl NQR spectroscopy for studies of the CCl 3 -group reorientation processes in hexachloroethane has been applied. It has been demonstrated that 2D NQR exchange spectroscopy is appropriate for quantitative studies of exchange processes in molecular crystals containing quadrupole nuclei. The method is of particular value for the detection of exchange networks in systems with many sites. Thus, detailed information on the exchange pathways within a network of structural isomers in hexachloroethane can be deduced and a proper assignment of the NQR lines can be made. Temperature dependence of the exchange rate was studied. The mixing dynamics by exchange and the expected cross-peak intensities have been derived. The very good agreement of the experimental results with theoretical predictions confirms the validity of the motion model.

Activity and selectivity of a 1 wt.% Pd/carbon catalyst in the hydrodechlorination of carbon tetrachloride into chloroform was studied in the liquid phase as a function of temperature (353–413 K) and reaction time. The catalyst was prepared by incipient wetness impregnation and reduced at 523 K, and the reaction performed in a three-phase bubble column reactor at 3 MPa. Reaction is highly selective towards chloroform, with dichloromethane, monochloromethane, hexachloroethane, tetrachloroethylene and methane as by-products. Increasing the temperature mainly favors the production of hexachloroethane and tetrachloroethylene, though the chloroform selectivity remains always above 90% even at conversion levels even higher than 90%. The reaction fits a zero order related to carbon tetrachloride up to 60% conversion at 413 K and even to higher conversions at lower temperatures. From the analysis of both product distribution versus time and reactivity of the reaction products, a reaction pathway is proposed. The results indicate that chloroform, hexachloroethane and methane are primary products, and that the carbon tetrachloride transformation proceeds via three parallel and independent paths. Chloroform, dichloro- and monochloromethanes are formed from tetrachloromethane by successive hydrodechlorination reactions (Path I), while hexachloroethane and tetrachloroethylene follow other parallel consecutive path (Path II). Methane is directly produced from tetrachloromethane (Path III). Paths I and II are conventional consecutive reactions in which the intermediates are desorbed to the gas/liquid phase as stable molecules and further readsorbed in order to give the following chemical species. In contrast, for methane the overall consecutive process occurs in the adsorbed phase, on the same active site, without the appearance of any intermediate molecular species.

Reaction of ketones with CS2 and 2 equivalents of KH in THF–N,N′-dimethylpropyleneurea solution produces the dianions of 3-oxodithioic acids. These dianions are converted in good yield to 3H-1,2-dithiole-3-thiones by the sequential action of hexamethyldisilathiane and an oxidizing agent such as hexachloroethane.

A new and efficient chlorination protocol is presented for the preparation of chlorosilanes from hydrosilanes. A variety of chlorinating agents in combination with palladium(II) chloride as the catalyst are examined. Among them, hexachloroethane is found to be the best choice, furnishing the desired product in good to quantitative yields under mild conditions. Various hydrosilanes are used as starting materials to explore the scope of this reaction.

Efficient design of zero-valent metal permeable `barriers' for the reduction of organohalides requires information regarding the pertinent reaction rates as well as an understanding of the resultant distribution of products. In this study, the pathways and kinetics for reaction of polychlorinated ethanes with Zn(0) have been examined in batch reactors. Reductive β-elimination was the only route through which hexachloroethane (HCA), 1,1,1,2-tetrachloroethane (1,1,1,2-TeCA), 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA), 1,1,2-trichloroethane (1,1,2-TCA) and 1,2-dichloroethane (1,2-DCA) reacted. Pentachloroethane (PCA) reacted via concurrent reductive β-elimination (93%) and hydrolysis (7%). As previously demonstrated, 1,1,1-trichloroethane (1,1,1-TCA) and 1,1-dichloroethane (1,1-DCA) reacted predominantly via reductive α-elimination. Attempts to correlate BET surface area-normalized rate constants (kSA-BET) with one-electron reduction potential (E1) met with limited success, as HCA, PCA, 1,1,1,2-TeCA, and 1,1,1-TCA reacted at nearly identical rates despite substantial differences in E1 values. Comparison of the pseudo-first-order rate constants (kobs) for these species with rate constants (kLa) obtained from a correlation for mass transfer to suspended particles revealed that the reaction of these species was mass transfer limited even though reaction rates were unaffected by mixing speed. Calculations suggest that mass transfer limitations may also play a role in the design of treatment systems for highly reactive species, with overall rate constants predicted to increase with flow velocity.

An easy and efficient synthesis of 4-aminoquinolines substituted with a phosphorylated group or a phosphine oxide group in the 3-position is described. The key step is a regioselective addition of lithiated β-enamino phosphonates to isocyanates to give functionalized amides. Subsequent cyclization of these compounds with triphenylphosphine and hexachloroethane in the presence of triethylamine afforded substituted 4-aminoquinolines. The deprotection of N -PMP substituted 4-amino-quinolines with CAN in acetonitrile gave primary 4-aminoquinolines.

Irradiation for permethyloligogermanes, Me(Me 2 Ge) n Me ( n =2–5), in CCl 4 –CH 3 CN in the presence of 9,10-dicyanoanthracene (DCA) afforded the corresponding chlorogermanes and hexachloroethane. Fluorescence of DCA was quenched by the oligogermane with a diffusion-controlled rate. A mechanism of free-radical chlorination involving oligogermane cation radicals and a DCA anion radical is proposed for the germanium–germanium cleavage.

Mutation of the conserved Thr319 residue to Ala of cytochrome P4501A2 (CYP1A2) increased the value of Vmax 9-fold for reductive dehalogenation of hexachloroethane in the reconstituted system under anaerobic conditions. The Thr319Ala mutation also increased the elimination over substitution product ratio by 5-fold. The addition of aliphatic alcohols increased by 22-fold the activity obtained with the wild type and varied the elimination over substitution product ratio. Increasing pH increased the ratio of elimination over substitution by primarily affecting the rate of elimination.

International audience; The selective electrophilic monofluorination and monochlorination of a wide variety of diethyl benzylphosphonates have been realized in a one-pot procedure. The monohalogenation was accomplished by intermediate of a benzylic carbanion protected with TMSCl using N-fluorobenzenesulfonimide (NFBS) and hexachloroethane, respectively. After mild removal of protecting group, this procedure delivers the α-monohalogenobenzylphosphonates in high yields (68-97%) and pure form.

A thermodynamic assessment was made of the (plastic—crystalline solid + liquid) phase diagram in the system carbon tetrabromide + hexachloroethane. The phase diagram is an example of crossed isodimorphism: two (plastic—crystalline solid + liquid) loops crossing each other give rise to a three-phase equilibrium (in this case eutectic). The information used consisted of experimental liquidus data, the thermodynamic melting properties of the pure components and the enthalpy of fusion data of the mixed plastic-crystalline solid state with the hexachloroethane structure. The eutectic is an organic analog for the investigation of eutectic growth in metallic systems. The eutectic temperature is 357.55 K and the calculated eutectic mole fractions are 0.094 (solid), 0.118 (liquid) and 0.187 (solid). The values of the initial distribution coefficients are (i) at the carbon tetrabromide side; k00 = 0.79 ± 0.06; (ii) at the hexachloroethane side; k00 = 0.58.

Within the study of the formation of chlorinated dioxins and dibenzofurans and their precursors the thermolysis of hexachloroethane over the aluminum melt was investigated. «De novo» synthesis of precursors of PCDD/F was studied in the model system AlCl 3 /elemental carbon. Totally chlorinated heterocyclic compounds have been detected parallel with the formation of organochlorine compounds. The possibility of inserting oxygen to aluminum organyls was presented. In order to gain more detailed knowledge of the catalytic behaviour of fly ash the chemistry of thermolysis of phenoxy- and chlorophenoxy aluminum compounds at 300 o C with the presence and absence of Al 2 O 3 was investigated. Reagent compounds and products of thermolysis were followed by mass spectrometry

In order to gain insight into mechanisms of hexachloroethane reduction, hexa- and pentachloroethane transformation rates were measured in anaerobic groundwater samples. For samples spiked with pentachloroethane, disappearance of pentachloroethane was accompanied by tetrachloroethylene production. Transformation rates were similar in unpoisoned and in HgCl2-poisoned samples, and rates were within ±20% of predictions based on measured pH and second-order dehydrochlorination rate constants determined in clean laboratory systems, indicating that the fate of pentachloroethane in this system is dominated by abiotic reactions. No hexachloroethane transformation was observed in HgCl2-poisoned samples, whereas in unpoisoned samples, hexachloroethane disappearance was accompanied by production of tetrachloroethylene as well as traces of pentachloroethane. Although only minor amounts of pentachloroethane accumulated, as much as 30% of the hexachloroethane transformation pathway proceeds via a pentachloroethane intermediate. This suggests that the microbial reduction of hexachloroethane proceeds at least in part through a free-radical mechanism. To the extent that hexachloroethane reduction to tetrachloroethylene occurs through a pentachloroethane intermediate, the first step in the sequence, the microbially-mediated step, is the slow step; the subsequent abiotic dehydrohalogenation step occurs much more rapidly.

A new dichlorination procedure of CC double bond was developed with hexachloroethane as chlorinating agent and RuCl2(PPh3)3 as catalyst. The reaction is highly selective for CC double bond; other functional groups are unaffected by these conditions.

A physiologically-based toxicokinetic model for fish was used to describe the uptake and disposition of three chlorinated ethanes in channel catfish (Ictalurus punctatus). Catfish were simultaneously exposed to 1,1,2,2-tetrachloroethane (TCE), pentachloroethane (PCE), and hexachloroethane (HCE) in fish respirometer-metabolism chambers to assess the kinetics of chemical accumulation in arterial blood and chemical extraction efficiency from inspired water. Chemical residues in tissues were measured at the end of each experiment. These data were used to evaluate the accuracy of model simulations and to form a basis for comparison with information collected previously from rainbow trout. TCE was at or near steady-state in catfish after 48 h. For PCE and HCE the time to steady-state appeared to be considerably longer than 48 h. Parameterized with in vitro chemical partitioning information, the model accurately simulated the accumulation of TCE in arterial blood and its uptake from inspired water, but consistently underestimated the uptake and accumulation of both PCE and HCE. The cause of these discrepancies was not conclusively determined; however, several possible sources of error were evaluated, including physiological and chemical partitioning inputs, and underlying modeling assumptions. A comparison of data sets and modeling efforts for rainbow trout and channel catfish suggests that gross similarities between the two species can be attributed to the comparability of relevant physiological and chemical partitioning parameters.

A physiologically based toxicokinetic model for fish was used to simulate the uptake and disposition of three waterborne chloroethanes in rainbow trout (Oncorhynchus mykiss). Trout were exposed to 1,1,2,2-tetrachloroethane, pentachloroethane, and hexachloroethane in fish respirometer-metabolism chambers to assess the kinetics of chemical accumulation in arterial blood and chemical extraction efficiency from inspired water. Chemical residues in tissues were measured at the end of each experiment. Trout exposed to tetrachloroethane were close to steady-state in 48 hr. Fish exposed to pentachloroethane were near steady-state in 264 hr. Extraction efficiency data showed that systemic (extrabranchial) elimination of both chemicals was small. Hexachloroethane continued to accumulate in fish exposed for 600 hr. Parameterized with chemical partitioning data obtained in vitro, the model accurately simulated the uptake of all three chloroethanes in blood and tissues and their extraction from inspired water. These results provide support for the basic model structure and the accuracy of physiological input parameters.

A thermosonimetric study has shown that the Phase II/III polymorphic transition of hexachloroethane emits acoustic signals. This solid-solid phase transition is known to occur by a nucleation-growth process during which a nucleus of the new phase, once formed, grows at the expense of the mother phase to form a complete crystal without fracture. Acoustic emissions from a conditioned multi-crystal sample have been used to study the transition. Acoustic activity correlated well with dilatometric measurements. Frequency analysis on waveforms of many hundreds of individual acoustic emissions revealed marked differences between individual signals. Principal-components analysis on 24 signal features revealed a single dispersed cluster with a highly non-uniform distribution of signals. These experiments provided highly reproducible average power spectra. Time-resolved acoustic power spectra were also generated. These additional types of information cannot be obtained by other techniques.

Thermal decomposition of trichloroethylene was investigated by means of passing air containing trichloroethylene vapor through a quartz tube heated at 300 to 800°C in order to establish an effective decomposition method for waste trichloroethylene. Main pyrolysis products were carbon tetrachloride, tetrachloroethylene, hexachloroethane, hexachlorobutadiene, and hexachlorobenzene. More than 99% trichloroethylene was decomposed by heating over 500°C.

The nanoscale particles of silver and copper coated with amorphous carbon (Ag/C and Cu/C) react with liquid carbon tetrachloride at 25–30°C to selectively form hexachloroethane in 60% yield.

A systematic study on the synthesis of carbon-encapsulated magnetic nanoparticles by self-sustaining high-temperature synthesis (SHS) is presented. The SHS was carried out using NaN 3 as a reducer; and poly(tetrafluoroethene) (C 2 F 4 ) n , hexachloroethane (C 2 Cl 6 ) and hexachlorobenzene (C 6 Cl 6 ) as three various oxidizers. The effect of metal precursor, (Fe(CO) 5 or K 3 [Fe(CN) 6 ]) on the yield, reaction heat, morphology, structure and magnetic properties of the products was investigated. The highest product yield with best magnetic characteristics was obtained from the organometallic iron precursor and C 2 Cl 6 oxidizer.

Various types of obscurant smokes are used routinely in training by the U.S. Army. Because continued routine use of the smokes could be detrimental to the native flora and fauna at training sites, a preliminary biological and chemical field study of fogoil, hexachloroethane, and tank diesel smokes was conducted. Smoke plumes were sampled and chemically analyzed at distances of 15–150 m from the smoke source where Tradescantia clones 4430 and 03 and the native plant Ambrosia dumosa and the native rodent Dipodomys merriami were exposed for 30 min. In addition, Tradescantia clone 4430 was exposed to tank diesel in the laboratory at concentration levels equivalent to exposure at 15 and 50 m. Tradescantia clones were examined for mutagenic effects indicated by micronuclei induction in developing pollen and pink somatic mutations in stamen hairs. Photosynthetic perturbations were measured in Tradescantia and A. dumosa using variable fluorescence induction. Animals were examined for sister chromatid exchanges and chromosome aberrations. It was found that all of the smokes tested exerted varying degrees of physiological and mutagenic effects in one or more assay system at one or more exposure distance. The studies reported here indicate that exposed ecological systems, or at least components of these systems, are at a higher risk than are unexposed components (e.g., organisms) for several types of damage attributed to obscurant smoke exposure.

HC smoke, a wide-area obscurant used in large quantity during military training, is produced by reaction of zinc oxide (46.7%), hexachloroethane (46.7%

The cyclic sulfones 1 , 2 , and 3 are lithiated in benzene with n-butyllithium. Lithiation is demonstrated to lead to α-mono, α,α′-di and/or α,α-di and α,α,α′ trimetallation. The lithiated sulfones are chlorinated with hexachloroethane (HCE). Some mechanistic aspects of the reaction of the lithiosulfones with vicinal dihalides are discussed.

The separation of the products from the chlorination of ethane by temperature-programmed gas chromatography on a packed column was studied. The gas chromatogaphic behaviour of all nine possible components (from ethyl chloride to hexachloroethane) was chracterized by the retention indices on the following stationary phases: OV-101, HalocarbonK-352, SE-30, OV-17, methyl phenyl silicone oil MFSD-5, SP-2340 and β,β′-oxydipropionitrile. Quantitative analysis was accomplished with a flame-ionization detector, for which the correction factors of the chlorinated ethanes were determined.

The conversions of the transition from phase II to III of C2Cl6 were measured for the range between 38.81 and 41.15°C (the transition point: 43.64°C). A simple model was devised appropriate to the present mononucleus transition. Using this, the induction periods, that are inversely proportional to the nucleation rates, were extracted from the observed curves. The resulting induction periods varied from 0.07 to 1500 h. In terms of the classical nucleation theory, though its applicability for such a wide variation is questionable, it was shown that there are two temperature regions bounded at about 40.8°C in which nucleation behaviours are different. As shown in the previous papers, the growth rates of the same transition were too fast to measure below a certain threshold temperature which was lower than 41.9°C. These threshold behaviours in nucleation and growth were tentatively attributed to the change-over from metastability to unstability.

Lithiation of the sulfones 1–3 in THF at −78° with lithium diisopropyl amide (LDA) is regioselective, since deuteration of the α-lithiosulfone 4 results in formation of the α-monodeuteriated sulfone 7. Higher temperature causes an intramolecular 1,4-addition of the lithiated sulfone 4 to the lithiated cyclic sulfone 19 and an intermolecular 1,4-addition of the lithiated sulfones 5 and 6. The cyclisation of Z-sulfone 1 has been used for the isolation of the isomeric E-sulfone 2 from mixtures of 1 and 2. The lithiated sulfones 4–6 are chlorinated with hexachloroethane (HCE). Due to acid/base reactions the α,α-dichlorinated cyclic sulfone 23 and α,α'-dichlorinated butadienyl sulfones 13–15 are formed in small amounts.

Fluorination of hexachloroethane or of tetrachloroethylene + chlorine by hydrogen fluoride at ca. 400°C in the presence of an aluminium fluoride catalyst gives the unsymmetrical isomers of dichlorotetrafluoroethane and of trichlorotrifluoroethane as the major products. Under similar conditions but using a catalyst of aluminium fluoride containing small amounts of iron, chromium and nickel, symmetrical trichlorotrifluoroethane is the major product. Analogous fluorinations of various intermediates over these catalyst systems have been studied and detailed information about the reaction pathways obtained. Under suitable conditions, s-trichlorotrifluoroethane or s-dichlorotetrafluoroethane can be prepared in a high state of purity.

Eight chlorinated ethanes and 3 chlorinated ethylenes were tested in the BALB c -3T3 cell transformation assay. Under the conditions of the assay, vinyl chloride and 1,1,1-trichloroethane induced a clear positive transformation response while 1,1,2-trichloroethane and trichloroethylene were weakly positive. Chloroethane, 1,1- and 1,2-dichloroethane, 1,1,1,2- and 1,1,2,2-tetrachloroethane, hexachloroethane and tetrachloroethylene were all negative in the assay conducted in the absence of an exogenous metabolic activation system. These results suggest that the BALB c -3T3 cells possess capability to activate some, but not all, of the chlorinated hydrocarbons which exhibit species specificity in producing carcinogenicity in mice but not in rats.

Hypercoulometric response has been observed in a d.c. electron capture detector operated under special conditions: Its responses, as measured in faradays peak area per mole of compound injected, were higher than 1 for many organic halides and nitro compounds. Hexachloroethane, for instance, showed response values up to 40. Although the cause of this phenomenon has not been determined, it may have implications for certain studies in electron capture detection.

The cis fused bicyclic sulfones 1a, 1c and 3a are lithiated in benzene with n-butyllithium under concomitant cis/trans isomerization of the ring fusion, involving intramolecular proton transfer. H/D exchange of the three α-hydrogens in protic solvents proceeds with retention of configuration. The lithiated sulfones are chlorinated with hexachloroethane (HCE) and show a strong preference for introduction of halogen at an equatorial α-position.

The temperature dependences of both the resonance frequency ana the quadrupole spin-lattice relaxation time T I chlorine-35 of the solid hexachloroethane and tetrachloroethylene have been studied by the pulse method of the nuclear quadrupole resonance (NQR). From the data analysis a discovery of the existence of a reorientation motion of the molecules as a whole in these crystals occurred. The hindered motion barriers were evaluated from the dependence of T I (T) and are equal to 18.4 and 12.4 kcal/mole for C 2 Cl 6 and C 2 Cl 4 , respectively. The results obtained are discussed in comparison with the experimental and theoretical ones of other authors.

Results from molecular-mechanics calculations of conformational structures, energies, barrier heights and torsional force constants in halogenated disilanes, Cl3CCCl3 and Cl3SiCCl3 are given, together with force constants and reference values for bond lengths and bond angles in such molecules.

The carcinogenicity of chronically administered (41 to 103 weeks) technical-grade pentachloroethane (PCE) was assessed in groups of 50 male and female Fischer 344 rats and B6C3F 1 mice. The major contaminant in the PCE sample used for the chronic study was hexachloroethane (4.2%). Prechronic studies (two and 13 weeks repeated dose) employing gavage doses of from 5.0 to 1000 mg/kg/day of PCE failed to reveal specific target organ toxicity in these species. In the absence of treatment-related pathological changes during the prechronic tests, the doses for the chronic studies were set on the basis of survival and body weight gains during the 13-week repeated dose study. During the chronic studies dose levels of 75 and 150 mg/kg for rats and 250 and 500 mg/kg for mice were administered, by gavage, five days per week. The survival of high-dose rats (both sexes) was significantly reduced as compared to the survival of control animals and that of the low-dose males was slightly, but not significantly, reduced. Although the administration of PCE to rats did not increase the incidence of primary tumors, it did produce a significant dose-related increase in the incidence of chronic renal inflammation among males. The survival times of all treated groups of mice were significantly shortened by PCE administration. Despite this reduced survival time, the incidence of hepatocellular carcinoma was significantly increased in all treated groups. With the exception of a dose-related increase in the incidence of hepatocellular adenoma among females, there were no other significant increases in primary tumor incidence in mice. Neither renal lesions in rats nor hepatocellular carcinoma in mice were considered to be adequate explanations for the decreased survivals. Complete histopathological examinations failed to reveal the cause of decreased survival. The results of the study show that technical-grade PCE, like numerous other chlorinated ethanes, is an hepatocarcinogen for B6C3F 1 mice. This interpretation for PCE per se , however, must be tempered because the major contaminant, hexachloroethane, has been shown to produce hepatocellular carcinoma in mice. While the results obtained in rats suggest a species difference in susceptibility, the reduced survival in this species may have contributed to the absence of a carcinogenic effect.

From incoherent inelastic neutron scattering studies of solid C 2 Cl 6 the in- and out-of-phase torsions about the C-C axis are assigned at 56 and 95 cm −1 , respectively. Using a model for the potential barriers in the solid the torsional frequency in the gas has been calculated to be 76.7 cm −1 and the internal barrier to be 67.8 kJ mol −1 .

The EPA Mobile Incinerator has demonstrated its ability to successfully destroy dioxin. A trial burn conducted in 1987 demonstrated the incinerator's ability to destroy a wide variety of compounds. The destruction and removal efficiency (DRE) of carbon tetrachloride, hexachloroethane, and trichlorobenzene was greater than the required 99.99%, and the DRE for PCBs was greater than the required 99.9999%. The field demonstration of the mobile incinerator that began in 1985 is scheduled for completion in 1989 after incinerating 4,530,000 kg of waste material.

At the Canadian Forces Base, Borden, hexachloroethane (HCE) that was introduced into an unconfined sand aquifer disappeared rapidly, with a half-life of about 40 days. Laboratory-scale studies, initiated to help assess the fate of HCE, indicated that it is reductively biotransformed to tetrachloroethylene (PCE) both by aerobic cultures of wastewater microflora and by microcosms containing unhomogenized Borden aquifer material. The results also indicate that the agents involved in the aquifer transformation of HCE to PCE are not homogeneously distributed in the aquifer material.

The transformability of trihalomethanes, carbon tetrachloride, 1,1,1-trichloroethane, 1,2-dibromoethane, tetrachloroethylene, hexachloroethane, and dibromochloropropane was studied under conditions of denitrification, sulfate respiration, and methanogenesis. These compounds at concentrations commonly found in groundwater were continuously administered to anoxic biofilm columns that resembled groundwater environments. Acetate was the primary substrate to support microbial growth. All of the compounds studied were transformed under methanogenesis. Bromoform, bromodichloromethane, carbon tetrachloride, and hexachloroethane were transformed even under the less reducing conditions of denitrification. Some of the compounds were partially mineralized to CO 2 . However, reductive dehalogenation appeared to be the predominant mechanism for removal. Characterization of the available electron acceptors in the subsurface is important for assessing organic micropollutant biotransformation. Reaction rates observed in the laboratory biofilms indicate that biotransformation could be responsible for significant removals of these halogenated compounds in the subsurface.