Halogenated ethanes

C2F5Br absorbs at 193 nm but not at 248 nm. At the shorter wavelength photodissociation occurs via 

The CM recoil energy of the fragments was 30 kcal/mol with a FWHM 

C2F5I absorbs at 248 nm but not at 193 nm. TOF measurements of the photodissociation products at the former wavelength indicate that the I atom is produced only in the state, which 

The anisotropy parameter indicates that this is a parallel transition ( Qg - N) and the absorption coefficient suggests that it is much stronger than the corresponding CH Br transition. While the authors suggest that this is a mystery, it could be that the absorption strength is a result of the heavy I atom breaking down the spin selection rule. 

Wight and Leone have remeasured the I( 1/2) yield at 193 nm, and found that the yield is 0.50 0.14, while it is 0.14 0.04 for the Br(2pj/2) channel. Krajonovich et al. (193) have shown that the total yield of Br is 0.33, so that the yield for Br Pg ) must be 0.33 - 0.14 = 0.19. The corresponding yield that Wight and Leone measured for the I ( 1/2) state is in agreement, within their experimental error, with the TOF results, suggesting that most of the I atoms are produced electronically excited. The TOF studies (198) of the photodissociation of 1,2-chloroiodoethane at 248 and 266 indicate that the only two important primary process are 

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Jafvert, C.T. and Wolfe, N.L. Degradation of selected halogenated ethanes in anoxic sediment-water systems. Environ. Toxicol C/je/n,.6(ll) 827-837. 1987. 

National Toxicology Program NTP Technical Report on Renal Toxicity Studies of Selected Halogenated Ethanes Administered by Gavage to F344/N Rats. Technical Report Series No. 45, NIH Pub No 96-3935, pp 1-52. Research Triangle Park, NC, US Department of Health and Human Services, 1996... 

Permeation of Protective Garment Materials by Liquid Halogenated Ethanes and a Polychlorinated Biphenyl... 

Despite the hazards involved in the use of these compounds, the halogenated ethanes find continued widespread use and the PCBs are widely encountered, although their original roles are being satisfied through replacement by other substances and they are no longer being manufactured nor imported into the United States. 

Because of the wide scope of usage of these materials and their associated risks, the present study was performed to determine those protective garment materials which would afford the highest degree of protection against the halogenated ethanes and the particular PCB (Aroclor-1254) chosen for this study. 

To determine the volume change of a given material following immersion, 1" by ln pieces of the subject materials were individually placed in beakers which contained the halogenated ethanes and the particular PCB of this study. At 1, 4, and 24h following immersion, the material was removed from its solvent and dimensional measurements obtained within 1 min. following removal. 

Experiments were performed to determine the rate at which the halogenated ethanes and the PCB used in this study permeated various protective garment materials. Discrete, rather than continuous, sampling was employed for these studies and because of the hazardous nature of the compounds employed, the experiments were performed in a chemical fume hood having a face velocity >125 linear ft./min. 

A zero time base for the halogenated ethane permeation studies was established as follows The aqueous side of the cell was filled with 100 mL of water and allowed to reach thermal equilibrium with the water bath. Likewise, the particular organic compound being tested... 

For both the halogenated ethanes and the PCBs, in those cases where a positive organic concentration value was obtained, i.e., after breakthrough, it was necessary to mathematically correct the observed concentration to compensate for dilution effects. Because of sequential dilutions during sampling, the true organic concentration for each discrete sample was calculated from the formula.(13) ... 

Protective Garment Materials Permeation by Halogenated Ethanes (1,2-Dichloroethane 1,1,1-Tricloroethane and 1.1,2-Trichloroethane). Tables IV, V, and VI present the protective garment breakthrough times for 1,2-dichloroethane 1,1,1-trichloro-ethane and 1,1,2-trichloroethane for both the homogeneous, non-bonded materials and for the coated/bonded composite materials. 

Another important point which may be inferred from the limited data of Tables IV, V, and VI is that for compounds which are chemically similar, e.e., congeners or isomers as was the case for the halogenated ethanes, there may be appreciable differences in the rate at which they permeate given materials, and in many cases will show non-Fickian behavior as shown in the graphs of Fig. 9-18. 

Strobel, K. Grummt, T. (1987) Aliphatic and aromatic halocarbons as potential mutagens in drinking water. III. Halogenated ethanes and ethenes. Toxicol, environ. Chem., 15, 101-128... 

Jafvert and Wolfe (1987) studied the rate of disappearance of a series of halogenated ethanes in an anaerobic sediment-water slurry. They found the following initial pseudo-first-order rate constants, kobs, for the various compounds ... 

A series of halogenated ethanes 1 containing the trifluoromethyl group has been oxidized under various conditions.5-7 When water is present in the reaction mixture, the acid 3 is usually formed during the reaction when water is absent, the acid halide 2 formed can be hydrolyzed in a trap with water. Trifluoroacetaldehyde hydrate 4 is formed6 as a minor product in addition to the acid when 2-chloro-l,l,l-trifluoroethane is treated with oxygen and chlorine under UV irradiation with subsequent reflux of the mixture with hydrogen peroxide. 

TABLE D.4 AWPC-Temperature Functions (Eq. 12.5.1) for Halogenated Ethanes... 

Figure 10. Same as Fig. 9, but for fully halogenated ethanes and methyl chloroform. 

Horvath, A.L., Getzen, F.W. (1999a) IUPAC-NIST Solubility Data Series 67. Halogenated ethanes and ethenes with water. J. Phys. Chem. Ref. Data 28, 395-620. 

Brown, A.C., Canosa-Mas, C.E., Parr, A.D., Wayne, R.P (1990) Laboratory studies of some halogenated ethanes and ethers measurements of rates of reaction with OH and of infrared absorption cross-sections. Atmos. Environ. 24A, 2499-2511. 

Barbash J. E. (1993) Abiotic reactions of halogenated ethanes and ethylenes with sulfide, nitrate and pH-buffer anions in aqueous solution. PhD Dissertation, Department of Environmental Science and Engineering, Stanford University, Stanford, CA, 417p. 

Barbash J. E. and Reinhard M. (1992a) Abiotic reactions of halogenated ethanes and ethylenes in buffered aqueous solutions containing hydrogen sulfide. Prep. Ext. Abstr. Am. Chem. Soc. Div. Environ. Chem. 32(1), 670—673. 

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