Ethane 1,2-dibromo

One 1-ml aliquot is added to 1.0 ml of freshly-distilled 1,2-dibromo-ethane (bp 132°C) in an oven-dried flask which contains a static atmosphere of nitrogen or argon. After the resulting solution has been allowed to stand at 25°C for 5 min, it Is diluted with 10 rat of water and titrated for base content (residual base) to a phenolphthalein endpoint with standard 0.100 M hydrochloric acid. The second 1-mL aliquot is added cautiously to 10 ml of water and then titrated for base content (total base) to a phenol phthalein endpoint with standard aqueous 0.100 M hydrochloric acid. The methyllithium concentration is the difference between the total base and residual base concentrations.2 Alternatively, the methynithiura concentration may be determined by titration with a standard solution of sec-butyl alcohol employing 2,2 -bipyridyl as an indicator. 

The photoaddition of acenaphthylene to cyclopentadiene was shown to be sensitive to the presence of heavy atoms in the solvent, as shown in Table 10.9. The data in Table 10.9 show that product (46) increases from 18% of the total product in cyclohexane to 38% of the total product in 1,2-dibromo-ethane. This suggests that the [4 + 2] cycloaddition products (47) and (48) and the [2 + 2] product (46) are produced from different excited states. Accordingly, some of the [4 + 2] product has been postulated to arise from either (a) a singlet excited state or (b) a vibrationally excited ground state... 

Under similar conditions, phenylacetonitrile reacts with sulphur and 1,2-dibromo-ethane to produce, in low yield, the thioacetal together with the dicyanostilbene [51 ] (Scheme 4.10). 

This Statement was prepared to give you information about 1, 2-dibromoethane (ethylene dibromide, EDB) and to emphasize the human health effects that may result from exposure to it. The Environmental Protection Agency (EPA) has identified 1,177 sites on its National Priorities List (NPL). 1,2-Dibromoethane has been found at 9 of these sites. However, we do not know how many of the 1,177 NPL sites have been evaluated for 1,2-dibromo-ethane. As EPA evaluates more sites, the number of sites at which 1,2-dibromoethane is found may change. The information is important to you because 1,2-dibromoethane may cause harmful health effects and because these sites are potential or actual sources of human exposure to 1,2-dibromoethane. 

Reznik, G, Stinson, S.F. Ward, J.M. (1980) Respiratory pathology in rats and mice after inhalation of l,2.-dibromo-3-chloropropane or 1,2-dibromo-ethane for 13 weeks. Arch. Toxicol., 46, 233-240... 

Deuterium kinetic isotope effects in the dehydrobromination of the 1,2-dibromo-ethanes CH2Br CH2Br and CD2Br CD2Br [172]... 

Dihydro-1,4-benzoxazines (342) are prepared from 2-hydroxyacetanilides (341) with 1,2-dibromo-ethane and sodium hydroxide in acetonitrile containing a phase transfer catalyst (79S541). 1,1-Dioxides of dihydro-1,4-benzothiazines (344) are generated through the cyclization of imines (343) with methanesulfonyl chloride in the presence of triethylamine (79CI(L)26). 

Unfortunately yields are low when this reaction is extended to 1,2-dibromo-ethane, possibly because of steric problems and/or elimination of HBr. 

Endrin aldehyde Ethane, chloro- (ethyl chloride) Ethane, 1,2-Dibromo-Ethane, 1,1-Dichloro- (ethylene dichloride)... 

For large-scale synthesis of physostigmine, Julian and Pikl (38) devised a simpler route to the key intermediate XXII. Condensation of the sodium salt of 5-ethoxy-1,3-dimethyloxindole with 1,2-dibromo-ethane yielded 3- -bromoethyl-5-ethoxy-l,3-dimethyloxindole, which on heating with methylamine in methanol at 100° gave the V-methyl-amine XXII directly. 

Quinoline red dyestuffs which are prepared by quaternization with benzalchloride, diphenyldichloromethane, phosgene, or 1,2-dibromo-ethane exist only as form 25 (see Fig. 13). 

Homopiperazinium salts (153) have been prepared by reaction of 154 with 1,3-dibromopropane157 158 or 155 with 1,2-dibromo-ethane.167 Similar reactions were also carried out using a variety of... 

Ynamines are obtained by thiol elimination from ketene 5, A -acetals (1-aIkylthio-l-dialkylaminoalkenes) in 40-50% yields on treatment with LiNEt, at 20 °C or with NaNHo in boiling piperidine, or by leading them over solid NaNH.j at 150-165 °C. In the first two procedures the formed ynamines are fractionally distilled from the reaction mixture (equation 83) . When elimination is effected with KNHj in HMPT, aqueous work-up leads to the hydration of the ynamine. Therefore, 1,2-dibromo-ethane is added to the reaction mixture. It functions as a proton donor for the... 

One problem, as shown by the synthesis of (141), is the poor control over double oxidation of both phosphorus centers when preparing mixed phosphine-phosphine oxide ligands. One attractive solution, developed by Grushin, is a catalytic method using simple Pd(II) salts, 1,2-dibromo-ethane under biphasic conditions. In this manner (147) was prepared in high yield (>70%).308... 

Thus a support-bound benzylpiperazine (282) was allowed to undergo a Man-nich reaction with formaldehyde and a-keto-aldehyde hydrazones. Upon addition of 1,2-dibromo-ethane (388) the support-bound piperazine tether is N, N -dialky-lated to give a quinuclidinium species (389). Subsequent Hoffmann elimination released a diazaalkadiene (390) from the polymeric support, allowing it to react with isonitriles to give pyrazoles (395). With electron-rich dienophiles, HDA reactions were also reported to have been performed to yield compound (393) (Scheme 80). 

Steinberg, S.M., J.J. Pignatello, and B.L. Sawhney. 1987. Persistence of 1,2-dibromo-ethane in soils entrapment in intraparticle micropores. Environ. Sci. Technol. 21 1201-1208. 

Reductive dechlorination in combination with the elimination of chloride has been demonstrated in a strain of Clostridium rectum (Ohisa et al. 1982) y-hexachlorocyclohexene formed 1,2,4-trichlorobenzene and y-1,3,4,5,6-pen-tachlorocyclohexene formed 1,4-dichlorobenzene (Figure 6.72). It was suggested that this reductive dechlorination is coupled to the synthesis of ATP, and this possibility has been clearly demonstrated during the dehalogenation of 3-chlorobenzoate coupled to the oxidation of formate in Desulfomonile tied-jei (Mohn and Tiedje 1991). Combined reduction and elimination has also been demonstrated in methanogenic cultures that transform 1,2-dibromo-ethane to ethene and 1,2-dibromoethene to ethyne (Belay and Daniels 1987). 

CrfliBrj 1,2-Dibromo- ethane 131.5 CiHuO Isoamyl alcohol 131.8 CtHiCl... 

Relative rates have been determined for the competitive methylations and also acetylations of azines. Pyridazine reacts faster than pyridines in both reactions this is interpreted in terms of pair-pair electron repulsion and the a-effect.272 An additivity approach provides reasonable predictions of isomer ratios of quaternization products of pyridazine and other azines.273 Reinvestigation of the quaternization of various amino- and diamino-pyridazines with methyl iodide shows that both 1- and 2-methyl derivatives were usually formed.274 3-Amino-6-chloropyridazine forms /V2-quaternary salts with a- and / -halo esters and 1,4-dibromobutane, but with 1,2-dibromo-ethane or 1,3-dibromopropane bicyclic products, are formed.275 Protonation and quaternization of 1,4,5,6-tetrahydropyridazines takes place at position 1, this being the more basic nitrogen.276... 

An alternative synthesis of 2,3-dihydro-1,4-dithiin employs an unsaturated dithiolate ion. Thus, c/5-l,2-ethylenedithiolate, generated from 1,2-dichloroethylene as shown, reacts with 1,2-dibromo-ethane to give the desired compound (Scheme 7) <91SM2093). 

U067. . U076. . Ethane, 1,2-dibromo-Ethane, 1,1-dichloro U206. . D-Glucopyranose, 2-deoxy-2(3-methyl-3-nitrosoureido)-... 

DMAD <74YZ607>, and of the 1,9a,9-benzologue of (7) from 8-quinolinethiol with 1,2-dibromo-ethane <93MI 823-10>. 

Mutagenic tests were positive, while the histidine reversion-Ames test gave inconclusive results (NIOSH 1986). 1,2-Dibromo-ethane is carcinogenic to animals and is suspected to cause cancer in hnmans. Inhalation of this componnd prodnced tnmors in the lungs and nose in mice and rats. Oral administration cansed cancers in the liver and gastrointestinal tract. 

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