1.2- Dibromoethane compounds

In the chronic inhalation bioassay of 1,2-dibromoethane conducted by NTP (1982) (discussed in Section 2.2.1.8), increased incidence of focal and centrilobular hepatocellular necrosis occurred in male and female F344 rats exposed to the highest dose (40 ppm) of 1,2-dibromoethane. Compound-related degenerative or necrotizing hepatocellular lesions did not occur in B6C3Fi mice following exposure to any concentration used. Liver lesions were not reported in rats after chronic inhalation exposure to 20 ppm 1,2-dibromoethane with or without 0.05% disulfiram in the diet however, hepatocellular tumors (not otherwise classified) were induced in exposed rats fed dietary disulfiram (Wong et al. 1982). Also see Section 2.2.1.8. 

Bromine is used in the manufacture of many important organic compounds including 1,2-dibromoethane (ethylene dibromide), added to petrol to prevent lead deposition which occurs by decomposition of the anti-knock —lead tetraethyl bromomethane (methyl bromide), a fumigating agent, and several compounds used to reduce flammability of polyester plastics and epoxide resins. Silver(I) bromide is used extensively in the photographic industry... 

In 1882, Will (90), by reacting CS2 with the product (56) resulting from the condensation of dibromoethane with N,N -diphenylthiourea, obtained the first derivative of thiazolidine-2-thione (57). He observed the reaction of 57 with methyl iodide to afford an addition compound (58). 

Quaternary Salts. Herbicides paraquat (20) and diquat (59) are the quaternary salts of 4,4 -bipyridine (19) and 2,2 -bipyridine with methyl chloride and 1,2-dibromoethane, respectively. Higher alkylpyridinium salts are used in the textile industry as dye ancillaries and spin bath additives. The higher alkylpyridinium salt, hexadecylpytidinium chloride [123-03-5] (67) (cetylpyridinium chloride) is a topical antiseptic. Amprolium (62), a quaternary salt of a-picohne (2), is a coccidiostat. Bisaryl salts of butylpyridinium bromide (or its lower 1-alkyl homologues) with aluminum chloride have been used as battery electrolytes (84), in aluminum electroplating baths (85), as Friedel-Crafts catalysts (86), and for the formylation of toluene by carbon monoxide (87) (see QuaternaryAA ONiUM compounds). 

Dibromoethane (ethylene dibromide) 2-Dibutylaminoethanol (aminoethanol compounds) Dibutyl phosphate... 

Although the polysulfur macrocycles became more interesting to the scientific community after Pedersen s report of the crown compounds (see Chap. 1), examples of such structures may be found in the literature dating back some time. The first report of a macrocyclic polysulfide appears to be that by Ray who found in 1920 that when 1,2-dimercaptoethane and 1,2-dibromoethane were heated with alcoholic potassium hydrogen sulfide as shown in Eq. (6.2), triethylene trisulfide (2) and a substance presumed to be triethylene tetrasulfide (3) could be isolated. 

There has been much interest recently in the reaction of a, o)-di-halogenoalkanes. 1,2-Dibromoethane reacts with phthalazine to give ethane 1,2-bis-phthalazinium dibromide (1), none of the mono salt being formed directly, but the same dibromo compound and a, a -dipyridyl give the cyclic compound 2. ... 

Tetrahydroimidazo[5,l-c][l,2,4]triazine 474 was prepared (79KGS1540) by treating imidazole derivatives 472 or 473 with hydrazine. Compound 473 was obtained by reaction of the respective imidazole with 1,2-dibromoethane or by the reaction of the alcohol derivative 471 with phosphorus tribromide. On the other hand, chlorination of471 with thionyl chloride gave 472 (Scheme 100). 

Halogenated phenols, particularly 2-bromo-, 2,4-dibromo-, and 2,4,6-tribromophenol, have been identified in automotive emissions and are the products of thermal reactions involving the dibromoethane fuel additive (Muller and Buser 1986). It could therefore no longer be assumed that such compounds are exclusively the products of biosynthesis by marine algae. 

Cyclopropyl sulfones were shown to be obtained either by cyclization of y-p-tosyloxy sulfones 232 with base or by treatment of phenylsulfonylacetonitrile 233a or ethyl phenyl sulfonyl acetate 233b with 1,2-dibromoethane in the presence of benzyltriethyl-ammonium chloride (BTEA) and alkali in good yields. Chang and Pinnick synthesized various cyclopropane derivatives 234 upon initial treatment of carbanions derived from cyclopropyl phenyl sulfone with either alkylating agents or a carbonyl compound and subsequent desulfonylation, as shown below. 

In the ring closure of 5-amino-2,3-dihydro-17/-l,2,4-triazolo-3-thione 431 (R = NH2) with 1,2-dibromoethane in the presence of sodium methoxide (2equiv), compound 42 was formed as the main product (Scheme 50) <2003JHC821>. Similarly, the same type of functionalized thiazolo[3,2-A][l,2,4]triazoles 440 and 441 were isolated in the reaction of 1,2-dibromoethane with 2,3-dihydro-17/-l,2,4-triazolo-3-thione (431, R = H) or 2,3-dihydro-5-methyl-l/7-l,2,4-triazolo-3-thione (431, R = Me), using DMF as the solvent in the presence of potassium carbonate and benzyltriethylammonium chloride (CBTEA) (Scheme 50) <2004PS(179)1799>. 

RCu(CN)ZnI.u These new copper reagents are prepared by reaction of primary or secondary iodides with zinc that has been activated with 1,2-dibromoethane and chlorotrimethylsilane. The resulting organozinc compounds are then allowed to react with the THF-soluble CuCN-2LiCl (equation I). Because of the mild conditions, these new reagents can be prepared from iodides containing keto, ester, and nitrile groups. 

The following compounds were determined by this procedure chloroform bromoform 1,1,1-trichloroethane 1,1,2,2-tetrachloroethane trichloroethylene benzene carbon tetrachloride toluene bromodichloromethane chlorobenzene 1,1,2-trichloroethane o,p-xylene tetrachloroethylene o,p-chlorotoluene 1,2-dibromoethane and fluorobenzene (used as an internal standard). 

Of particular interest in the application of cyclodextrins is the enhancement of luminescence from molecules when they are present in a cyclodextrin cavity. Polynuclear aromatic hydrocarbons show virtually no phosphorescence in solution. If, however, these compounds in solution are encapsulated with 1,2-dibromoethane (enhances intersystem crossing by increasing spin-orbit coupling external heavy atom effect) in the cavities of P-cyclodextrin and nitrogen gas passed, intense phosphorescence emission occurs at room temperature. Cyclodextrins form complexes with guest molecules, which fit into the cavity so that the microenvironment around the guest molecule is different from that in... 

In the chronic gavage study of 1,2-dibromoethane conducted by NCI (1978), high-dose male Osborne-Mendel rats and B6C3P mice developed testicular atrophy. Because study animals had high compound- and gavage- related mortality and early onset of forestomach squamous cell carcinomas, it is difficult to determine from these results whether testicular atrophy (degeneration) was a primary (compound-induced) or secondary nonspecific) event. 

No studies were available in humans or animals regarding the distribution of 1,2-dibromoethane following dermal exposure. However, toxic effects observed in humans and animals after dermal exposure indicate that the compound is widely distributed throughout the body. 

Based on the rapid and extensive metabolism seen in all animals, the fate of 1,2-dibromoethane in humans would be expected to be similar. Seventy percent of the administered parent compound is excreted in the urine and feces by 48 hours. The lack of persistence of metabolites in the tissues indicate that 1,2-dibromoethane is readily removed from the body. Low-level exposure would not be expected to result in accumulation of 1,2-dibromoethane or its metabolites in human tissue. 

Primary biomarkers of exposure are the presence of 1,2-dibromoethane in blood or exhaled breath or excretion of specific metabolites in urine. In humans exposed to toxic levels of 1,2- dibromoethane (Letz et al. 1984), the parent compound was not measured in blood samples collected before death. However, two exposed individuals had elevated levels of serum bromide ions. This elevation is likely to have resulted from debromination of 1,2-dibromoethane during its metabolism. Elevated serum bromide is not specific to 1,2-dibromoethane exposure, but, rather, it is indicative of exposure to classes of brominated chemicals. 

Rats exposed acutely by gavage to 110 mg/kg of 1,2-dibromoethane in olive oil had elevated concentrations of the parent compound in the blood up to 30 minutes after exposure. At 2 and 4 hours postexposure, only trace amounts were detected and by 13 hours after exposure,... 

The most important route of exposure to 1,2-dibromoethane for most members of the general population is ingestion of contaminated drinking water. Individuals living in the vicinity of hazardous waste sites contaminated with 1,2-dibromoethane may be exposed to higher concentrations of the compound. 

EPA has identified 1,177 NPL sites. 1,2-Dibromoethane has been found at 9 of the total number of sites evaluated for that compound. We do not know how many of the 1,177 sites have been evaluated for 1, 2-dibromoethane. As more sites are evaluated by EPA, this number may change (View 1989). The frequency of these sites within the United States can be seen in Figure 5-1. 

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