Dichlorobenzene isomers

Which one of the dichlorobenzene isomers does not have a dipole moment" Which one has the largest dipole moment" Compare your answers with the dipole moments calculated using the molecular modeling software in Learning By Modeling... 

The dichlorobenzene isomers have very similar vapor pressures making separation by distillation difficult. Crystallization is generally used in combination with distillation to obtain the pure 1,2 and 1,4-dichlorobenzene isomers. The small quantity of 1,3-dichlorobenzene isomer produced is not generally isolated as a pure product. Environmental concerns have led to the use of improved crystalliza tion systems that contain the products with minimal losses to the environment. 

Bosma TNP, JR van der Meer, G Schraa, ME Tros, AJB Zehnder (1988) Reductive dechlorination of all tri-chloro- and dichlorobenzene isomers. EEMS Microbiol Ecol 53 223-239. 

Ishiyama, K. and Watanabe, M. (1999) Separation of dichlorobenzene isomer. Jpn Patent 11180911. 

Guo, G. and Long, Y. (2001) Static equilibrium studies on separation of dichlorobenzene isomers on binder-free hydrophobic adsorlaent of MFI type zeolite. Sep. Purif. Technol,... 

Dichlorobenzene was reported in drinking water samples from 3 cities on Lake Ontario at concentrations ranging from 8 to 20 ppt (Oliver and Nicol 1982a). Dichlorobenzene isomers were detected in 0-3% of drinking water samples from selected locations in New Jersey, North Carolina, and North Dakota locations (Wallace et al. 1986a). 

Fisher R, Barr J, Zuloski CF, et al. 1991. In-vitro hepatotoxicity of three dichlorobenzene isomers in human liver slices. Hum Exp Toxicol 10 357-363. 

Valentovic AlA, Ball JG, Anestis D, et al Acute hepatic and renal toxicity of dichlorobenzene isomers in Fischer 344 rats. J Appl Toxicol 13 1-7, 1993... 

To determine the preferred mode of addition at high temperatures, solutions of 1-48 g (0-01 mole) of phthalic anhydride in 14-7 g (0-1 mole) of each dichlorobenzene isomer were pyrolyzed at 690° under nitrogen in a Vycor tube filled with Vycor beads (Meyerson and Fields, 1966b). Contact time was 22 sec. The products remaining after removal of excess dichlorobenzene (1 15 g, 1-6 g, and 1-06 g, respectively, from the ortho, meta, and para isomers) were analyzed by mass spectrometry. 

Tetrachloroanthracene was formed in low yields the values for the o-, m-, and -dichlorobenzene isomers, respectively, on the same scale as in the Table were 2, 1, and 0, about in the expected proportions. 

Photoinduced dehalogenation of dichlorobenzene isomers and their monosubstituted derivatives (30 compounds) is reported to give the corresponding monochlorobenzenes363. Upon irradiation in CD3OD the compounds underwent exchange of one of the chlorine atoms with deuterium. 

Direct oxidation of the lesser chlorinated ethenes, ethanes, polychlorinated benzenes, and chlorobenzene has been reported. Wiedemeier et al. [25] summarize a number of studies that report direct aerobic oxidation of vinyl chloride (VC), 1,2-dichloroethane, the three dichlorobenzene isomers, 1,2,4-trichlorobenzene, and 1,2,4,5-tetrachlorobenzene. Bradley [33] reports that DCE has served as a primary substrate for energy production with oxygen as the electron acceptor, though use of DCE as a sole carbon source has not been demonstrated. Rittmann and McCarty [29] also report that the two least chlorinated methanes (dichloromethane and chloromethane) as well as chloroethane can be directly oxidized under aerobic conditions. Direct oxidation of the chlorinated compounds is typically modeled using either first-order or Monod kinetics [29,31]. 

Example The three possible dichlorobenzene isomers are shown in the diagram on the right. 

A significant number of chlorinated haloethers, chlorinated hydrocarbons, and chlorinated benzenes are SVOCs. Examples include bis(2-chloroisopropylether), 4-chlorophenylphenylether, hexachloroelhane, isomers of dichlorobenzene, isomers of trichlorobenze, isomers of tetrachlorobenzene, pentachlorobenzene, and hexachlorobenzene, to name only a few. A number of nitroaromatic SVOCs are considered enviromnentally significant. Remedial action at an old military installation might reqnire the determination of isomers of nitrobenzene, dinitrobenzene, dinitrotoluene, and trinitrotoluene (TNT) in soil and water samples, because they are indicative of explosives. 

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