Carbon tetrachloride, enhancement

Sodium diethyldithiocarbamate, (C2H5)2N CS S Na+. This reagent is generally used as a 2 per cent aqueous solution it decomposes rapidly in solutions of low pH. It is an effective extraction reagent for over 20 metals into various organic solvents, such as chloroform, carbon tetrachloride, and ethanol. The selectivity is enhanced by the control of pH and the addition of masking agents. 

Solutions in organic solvents may, with certain reservations, be used directly, provided that the viscosity of the solution is not very different from that of an aqueous solution. The important consideration is that the solvent should not lead to any disturbance of the flame an extreme example of this is carbon tetrachloride, which may extinguish an air-acetylene flame. In many cases, suitable organic solvents [e.g. 4-methylpentan-2-one (methyl isobutyl ketone) and the hydrocarbon mixture sold as white spirit ] give enhanced production of ground-state gaseous atoms and lead to about three times the sensitivity... 

Noda T, Morita S, Baba A (1994) Enhanced teratogenic activity of di-n-butyltin diaeetate by carbon tetrachloride pretreatment in rats. Food and Chemioal Toxicology, 32(4) 321-327. 

Steup DR, Wiersma D, McMillan DA, et al. 1991. Pretreatment with drinking water solutions containing trichloroethylene or chloroform enhances the hepatotoxicity of carbon tetrachloride in Fischer 344 rats. Fund Appl Toxicol 16 798-809. 

Hasham SA, DL Freedman (1999) Enhanced biotransformation of carbon tetrachloride by Acetobacterium woodii upon addition of hydroxycobalamin and fructose. Appl Environ Microbiol 65 4537-4542. 

ElSisi, A.E.D., Earnest, D.L. and Sipes, LG. (1993a). Vitamin-A potentiation of carbon tetrachloride hepatotoxicity -enhanced lipid peroxidation without enhanced biotransformation. Toxicol. Appl. Pharmacol. 119, 289-294. 

In order to determine the sensitivity of coumarin dimerization to heavy-atom perturbation, the direct photolysis was carried out in butyl chloride, propyl bromide, and ethyl iodide. Comparison of these results with those obtained in nonpolar solvents indicated that there was no significant change in the amount of the triplet-derived product (80) formed in the heavy-atom solvents as would be expected if heavy-atom perturbation were important.<90) More recent investigations,<93W however, of the formation of (79) in carbon tetrachloride indicate that halocarbon enhancement of the formation of this isomer exists. A direct measure of the intersystem quantum... 

Similar treatment of a trifluoroacetic acid solution of p-tolualdehyde with triethylsilane gives only a 20% yield of /7-xylene after 11 hours reaction time followed by basic workup. Use of 2.5 equivalents of dimethylphenylsilane enhances the yield to 52% after only 15 minutes. This reaction proceeds stepwise through the formation of a mixture of the trifluoroacetate and the symmetrical ether. These intermediates slowly form the desired /7-xylene product along with Friedel-Crafts side products under the reaction conditions (Eq. 192).73 Addition of co-solvents such as carbon tetrachloride or nitromethane helps reduce the amount of the Friedel-Crafts side products.73... 

Crude sulfur vesicants are relatively stable and stability increases with purity Distilled materials show very little decomposition on storage. Solvents such as carbon tetrachloride and chlorobenzene have been added to enhance stability of crude material. Agents can be stored in glass or steel containers, although pressure may develop in steel containers. Sulfur vesicants rapidly corrode brass and cast iron, and permeate into ordinary rubber. 

Photolysis of diazomethane in carbon-tetrachloride in the presence of benzophenone yields 1,1,1,2-tetrachloroethane showing an enhanced absorption due to the triplet carbene. The direct photolysis of diazomethane proceeds via singlet methylene CIDNP-studies of the photolysis of methyl-diazoacetate, for which a radical pair mechanism was suggested, were recently challenged 2). 

Several animal studies indicate that chloroform interacts with other chemicals within the organism. The lethal and hepatotoxic effects of chloroform were increased by dicophane (DDT) (McLean 1970) and phenobarbital (a long-acting barbiturate) in rats (Ekstrom et al. 1988 McLean 1970 Scholler 1970). Increased hepatotoxic and nephrotoxic effects were observed after interaction with ketonic solvents and ketonic chemicals in rats (Hewitt and Brown 1984 Hewitt et al. 1990) and in mice (Cianflone et al. 1980 Hewitt et al. 1979). The hepatotoxicity of chloroform was also enhanced by co-exposure to carbon tetrachloride in rats (Harris et al. 1982) and by co-exposure to ethanol in mice (Kutob and Plaa 1962). Furthermore, ethanol pretreatment in rats enhanced chloroform-induced hepatotoxicity (Wang et al. 1994) and increased the in vitro metabolism of chloroform (Sato et al. 1981). 

Fig. 4.12 Enhancement of Zn(ll) extraction, D Do, from 1 M NaC104 into carbon tetrachloride containing the complexing extractants acetylacetone (O), trifluoroacetone (A), or hexafluoroacetone ( ) as a function of the concentration of the adduct former trioctyl phosphine oxide (B). The curves are fitted with Eq. (4.50) using the constants log Km = 3.01 (AA), 6.70 (TEA), 7.0 (TEA), and Km = 4.66 (AA), nil (TEA), 11.6 (HEA). (Erom Ref. 24.)...

In animal studies acetone has been found to potentiate the toxicity of other solvents by altering their metabolism through induction of microsomal enzymes, particularly cytochrome P-450. Reported effects include enhancement of the ethanol-induced loss of righting reflex in mice by reduction of the elimination rate of ethanol increased hepatotoxicity of compounds such as carbon tetrachloride and trichloroethylene in the rat potentiation of acrylonitrile toxicity by altering the rate at which it is metabolized to cyanide and potentiation of the neurotoxicity of -hexane by altering the toxicokinetics of its 2,4-hexane-dione metabolite.Because occupationally exposed workers are most often exposed to a mixmre of solvents, use of the rule of additivity may underestimate the effect of combined exposures. ... 

When absorbed, isopropyl alcohol is oxidized in the liver at the hydroxyl moiety and converted to acetone." Occupational exposure to isopropyl alcohol can be biomonitored by means of urinalysis for acetone after exposures as low as 70ppm." The acetone metabolite may also be responsible for the enhanced toxicity of carbon tetrachloride following pretreatment of animals with isopropyl alcohol. Extra caution is in order when isopropyl alcohol is... 

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