1.2- Dibromoethane values

The double titration method, which involves the use of ben2ylchloride, 1,2-dibromoethane, or aUyl bromide, determines carbon-bound lithium indirectly (101,102). One sample of the //-butyUithium is hydroly2ed directly, and the resulting alkalinity is determined. A second sample is treated with ben2ylchloride and is then hydroly2ed and titrated with acid. The second value (free base) is subtracted from the first (total base) to give a measure of the actual carbon-bound lithium present (active base). 

As an illustration, let us take the case of 1,2 dibromoethane and see how far the calculated value of dipole agrees with the observed value. 

As the duration of exposure of the rats increased, the LC o (lethal concentration, 50% kill) value decreased. Maximum nonfatal single exposures for rats were 1.2 minutes at 10,000 ppm, 2.4 minutes at 5,000 ppm, 6 minutes at 3,000 ppm, 12 minutes at 1,600 ppm, 36 minutes at 400 ppm, 2 hours at 200 ppm, and 16 hours at 100 ppm, the longest exposure tested. In other species exposed to 1,2-dibromoethane by Rowe et al. (1952), maximum nonfatal single exposures for guinea pigs were 2 hours at 400 ppm and 7 hours at 200 ppm, the longest exposure tested. 

A decrease in male fertility to 49% below expected values (significant at p=0.05) was reported in one of four 1,2-dibromoethane manufacturing plants (Wong et al. 1979). After adjustment for workers who had vasectomies and one whose wife had a hysterectomy, the reduction in fertility was 29% and no longer significant at that level. 

Single-dose oral LD o values in rats, guinea pigs, rabbits, and mice were determined by Rowe et al. (1952) in a gavage study using 1,2-dibromoethane in olive oil. All reliable LDso values (lethal dose, 50% kill) for each species for the acute-duration category are recorded in Table 2-2 and plotted in Figure 2-2. 

Renal Effects. The patient described by Letz et al. (1984) (see Section 2.2.3.1) who lived for 64 hours after exposure to toxic levels of 1,2-dibromoethane had acute renal failure as evidenced by severe oliguria 24 hours after exposure and abnormal clinical chemistry values (blood urea nitrogen, creatinine, and serum uric acid). Severe metabolic acidosis was present despite two hemodialysis procedures. 

Dibromoethane has been detected in an estimated 0.23% of the groundwater samples analyzed for the 2,783 hazardous waste sites participating in the Contract Laboratory Program (CLP) a positive geometric mean concentration value was not reported. 1,2-Dibromoethane has not been detected in surface water samples taken at hazardous waste sites (CLPSD 1988). Note that the CLP Statistical Database (CLPSD) includes data from both NPL and non-NPL sites. 

Dibromoethane has also been detected in ambient air samples collected at two hazardous waste sites in New Jersey at geometric mean concentrations of 20- 50 ppt the maximum value reported was 6,710 ppt (La Regina et al. 1986). 

For compounds other than PAHs, unfortunately there are not enough data available that would allow a more general analysis of the concentration dependence of Kioc values. Nevertheless, a few additional observations may give us some better feeling of the magnitude of this dependence. For example, for sorption of smaller apolar and weakly monopolar compounds (e.g., benzene, chlorobenzene, 1,2-dichlorobenzene, tetrachloroethene, dibromoethane) to soil (Chiou and Kile, 1998) or aquifer materials (Xia and Ball, 1999 and 2000), not more than a factor of 2 difference in Kioc was found between low and high sorbate concentrations. A somewhat more pronounced effect (i.e., factor 2 to 3) was observed for sorption of the more polar... 

Typical acidic catalysts are silica—alumina, transition metal sulphates or chlorides, calcium phosphate etc. They are characterised by low deuterium kinetic isotope effects and low stereoselectivity (see Tables 8,11 and 12). These results correspond to the E2cA or El mechanisms, between which a transition may be observed due to the influence of the structure of the reactants, i.e. according to the polarity of the Ca—X and Cp—H bonds. Again, the reactions of 1,2-dibromoethane and 1,1,2,2-tetrachloroethane yielded the evidence. The deuterium kinetic isotope effect on silica—alumina was 1.0 for the dibromo-derivative, which indicates a pure El mechanism, whereas for the tetrachloro-derivative, the value of 1.5 was found. 

Since we are not told the values of the interactions for 1,2-dibromoethane, the diagram can only be qualitative. 

By evaluating the integrated intensities of the Raman bands at 551 and 659 cm attributed to the C-Br stretching vibrations of the gauche and the trans isomer of 1,2-dibromoethane, Spiekermann et al. (1976) obtained the following values for AH and AS ... 

Tables 3 and 4 contain results from a study of a series of coumarins and fiirocoumarins in, 1,2-dibromoethane, which found that the lactone carbonyl signal consistently appeared near 350 ppm more variability was seen for the single bonded oxygen, especially for the furocoumarins, typically appearing at 220 ppm [85]. Synthetic 3-aryl coumarins also exhibit 6(C=0) and 5(-0-) values near those mentioned above [86]. Recently, a study of a series of 7-substituted-4-methylcoumarins, with a wide range in electronic character of the substituents, demonstrated that the carbonyl signal is quite sensitive to substituent effects and that the NMR chemical shift is reasonably well correlated with the carbonyl oxygen AMI estimated electron density [87].

This reaction proceeds between Ga2Br4 and MeBr or EtBr to give isolable products. With higher alkyl bromides, the reactions are of little synthetic value because oxidative addition is followed by further reaction of the electron-pair acceptor acid RGaX2 with excess RX to give organic materials and the Ga(III) halide, Ga2Br6. Reaction with 1,2-dibromoethane leads to formation of ethene. ... 

Reactive halides, e.g., methyl iodide, ethyl bromide or 1,2-dibromoethane, help to overcome the induction period. Many other activating additions are of doubtful or limited value . 

Nonlinear isotherms have been reported particularly at low Cg values (Fig. 3.10a). The sorption of both dibromoethane (EDB) and the herbicide diuron (DUN) on a peat soil (49.3%OC) both show this response, which is more pronounced with the latter. A similar type of response is also observed in soils of lower organic carbon content. A competitive effect is also demonstrated with trichloroethylene and phenol suppressing the sorption of EDB and EDB (at a sufficient concentration), monuron and dichlorophenol affecting the sorption of diuron. The... 

Dibromoethane is moderate to highly toxic by ingestion. Its toxicity is far greater than that of 1,2-dichloroethane. An oral intake of 5 to 10 mL of the liquid can be fatal to humans. Death occurs from necrosis of the liver and kidney damage. The oral LD50 values varied between 50 and 125 mg/kg for different species of laboratory animals. 

Which of following liquids will completely wet PS n-hexadecane (27.6), formamide (58.2), acetone (23.3), watCT (72.8) and 1,1-dibromoethane (39.55) Explain briefly your answer. The values in parentheses are the smface tensions of the liquids, aU in mN m. ... 

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