Bromine derivatives

Bromine compounds are much more expensive than chlorine compounds and, since the atomic weight of bromine is about twice that of chlorine, the halogen cost incurred in the use of bromine compounds as intermediates is likely to be at least an order of magnitude greater than the cost of the corresponding chlorine compound. Not least for this reason, the synthesis of phosgene from bromine-containing compounds is unlikely to be economically practical and are probably not worthy of development on a purely commercial basis. However, C-Br bonds are more readily cleaved than C-CI bonds, and bromide is readily oxidized back to bromine. 

In general, as for chlorine derivatives, the presence of humidity or the increase in the temperature will increase the corrosion of aluminium in contact with bromine derivatives. 

Methyl bromide CH3Br, a nematicide, attacks aluminium it may violently decompose in contact with aluminium. 

In the presence of humidity, bromoform CHBfs will also attack aluminium. Adding an alkaline buffer (amines such as dimethylamine) to the product may inhibit the attack. Hot bromoform, even anhydrous, will attack aluminium. 

In the absence of humidity, aluminium resists dibromomethane CH2Br2. The attack in the presence of humidity can be inhibited by adding amines. 

Ethylbromide CH3CH2Br will attack aluminium, even cold and exempt of humidity. 1,1-Dibromoethane CH3CHBr2 has no action. 

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Butynediol is principally used in pickling and plating baths. Smak amounts are used in the manufacture of brominated derivatives, useful as flame retardants. Itwas formerly used in awkd oat herbicide, Carbyne (Barban), 4-chloro-2-butynyl-A/-(3-chlorophenyl)carbamate [101-27-9] C H Cl2N02 (77). 

V-Chlorosuccinimide [128-09-6] mp 150—151°C, forms orthorhombic crystals and has a chlorine-like odor it is prepared from succinimide and hypochlorous acid (114,115). Because of its powerhil germicide properties, it is used ia disiafectants for drinking water. Like its bromine derivative, it is also a halogenating agent. 

Methyl-heptenone also forms a bromine derivative which is well suited for the identification of the ketone. This body, which has the formula CgHjjBrgO. OH, melts at 98° to 99°, and is obtained as follows Three grams of methyl-heptenone are mixed with a solution containing 3 grams of caustic soda, 12 grams of bromine, and 100 c c. of water. After a time an oily substance is deposited, which is extracted with ether. The solvent is evaporated, and the residue, redissolved in ether, is treated with animal charcoal and filtered. On slow evaporation the product is obtained in well-defined crystals. 

Instead of the chloroethyl theophylline, it is also possible to use the corresponding bromine derivative. It was found that in this way the process is facilitated and the yield is improved. 

Among aromatic bromine derivates, only polybrominated biphenyl is known to have a porphyrogenic effect (ref. 24). From scarce data about the toxicity of 4 and 5 porphyrogenic activity in the case of repeated administration could be expected (refs. 25,26). No data are available concerning the remaining compounds. 

The analysis of pentaerythritols and brominated derivatives, which are fire retardants, may be performed by a number of techniques, some of which will be discussed here. Each procedure suffers from different drawbacks. The method chosen must answer the specific need of the analysis. We use the following abbreviations. 

The molecular point groups of (CF3)2S02, ( 03)2802 and (CBr3)2S02 can be either C2V or C2 according to electron diffraction and vibrational spectroscopic data. The molecular model and projection formula for ( 13)2802 are shown in Figure 11. The molecular geometry of the bromine derivative has not been determined but its vibrational... 

Halogen derivatives are hardly inflammable. Their behaviour depends on the halogen rate that is present in the molecule and its nature (brominated derivatives are less inflammable than chlorinated) as well as the temperature to which they are exposed. So some of them that used to be used as extinguishing... 

Bromoethane was used in sterilisation equipment to make diethyl ether atmospheres fireproof. This method is inefficient since 31 % brominated derivative should be used. Inflammability data regarding bromoethane vary from one author to the next. It is most often agreed that this compound has very narrow inflammability limits (13.5-14.5%). The range is more critical under pressure and is thought to reach 8.6-20%. 

During laboratory-scale fractional distillation of a mixture of the aniline and its mono- and di-brominated derivatives, an explosion occurred, attributed to the lability of the bromine substituent. 

Durene, pentamethyl benzene and hexamethyl benzene have usually been prepared from benzene or one of its methylated derivatives by the Friedel-Crafts synthesis.1 Durene has been made from bromine derivatives of methylated benzenes by the Fittig reaction.2 It has also been obtained in 20 per cent yield by passing methyl alcohol and acetone vapors over heated alu-... 

Entry to the ugibohlin, phakellin, and isophakellin ABC ring systems was achieved via intramolecular N(l)-C(3) cyclizations of the Weinreb amide 169 of pyrrole-proline 168 or its brominated derivatives to give the bispyrrolopyr-azine 170 (Scheme 12) <2005TL249>. 

Reaction of compound 37 with bromine in chloroform results in mono-bromination a to the sulfur. Treatment of this brominated derivative with NaBH3CN in AcOH gives a mixture of products resulting from reduction of the C=N double bond and of elimination of HBr. Reaction of 44 with sodium ethoxide results in the ethoxy-substituted derivative 45, whereas reaction with pyridine gives the dehydrobrominated derivative 46. Reaction of either 44 or 46 with sodium cyanide in dimethyl sulfoxide (DMSO) gives the cyano-derivative 47 <1983HCA971> (Scheme 13). 

One of the most important reactions of purines is the bromination of guanine or adenine at the C-8 position. It is this site that is the most common point of modification for bioconjugate techniques using purine bases (Figure 1.53). Either an aqueous solution of bromine or the compound N-bromosuccinimide can be used for this reaction. The brominated derivatives then can be used to couple amine-containing compounds to the pyrimidine ring structure by nucleophilic substitution (Chapter 27, Section 2.1). 

The associated bromine derivatives are prepared by a different procedure, involving bromodepheny lation ... 

In addition, brominated derivatives of alkylphenols (BrNPnEO and BrNPnEC) can be formed during chlorine disinfection of water if... 

Finally, it is interesting to note that brominated derivatives of NP included in the present study, estrogenic in the E-Screen bioassay, were proposed to be fat-soluble [30], In fact, as non-ionic surfactants, these molecules have a hydrophilic and a hydrophobic part [31]. The presence of these brominated compounds in fat tissue of humans or animals has yet to be demonstrated. However, if they do bioaccumulate in adipose tissue, as their fat solubility suggests, they may account for the xenoestrogen burden alongside organohalogenated compounds. 

A second method is due to J. von Braun and consists in the addition of cyanogen bromide to tertiary cyclic bases.1 In the unstable addition product a C—N-linkage is broken and at the same time the bromine wanders to a new position. A brominated derivative of cyanamide is produced and this, on hydrolysis, yields a secondary amine which can be broken down further, e.g. 

Chlorination of waters containing two phenylurea-type herbicides, isoproturon and diuron, results in the formation of THMs. The reaction of the phenylurea-type herbicide isoproturon with chlorine produced compounds that still contained the aromatic ring of the herbicide with the urea side-chain unmodified. The formation of chlorinated and brominated derivatives was related to the bromide concentration present in the water [113]. 

Bromine is another candidate for water disinfection. This element is very corrosive and requires special techniques for handling, however, a bromine derivative, BrCl is much less corrosive and is known to be a more effective bactericide [1 ]. 

Iodinated or brominated, derivatives of amino-isophthalic acid 1-2 EPOl18349 Dimo/Guerbet 18... 

It was also synthesised by E. Fischer in 1901 from 7-phthalimido-propylmalonic ester which he employed in the preparation of ornithine. The bromine derivative of this compound when treated with ammonia gave a complex mixture of products which after hydrolysis by hydrochloric acid at 100° C. gave phthalimide and a-pyrrolidine carboxylic acid —... 

CHCI3. The organic layer was evaporated to dryness and the residue dried at 105 C for 3 hours. Chlorpromazine was weighed as its brominated derivative. 

The detection and monitoring of bromine is important in various fields of application. In industrial processes, bromine is employed, for example, for the desulfurization of flue gas and an on-line detector enables the process to be optimized. The presence of bromine in the atmosphere has been implicated in processes such as ozone depletion, [145] and devices for monitoring the release of bromine and bromine derivatives are desirable. Bromide monitoring is of interest in industrial contexts, photographic developers, environmental, and in medical samples. 

The dysideathiazoles A-E (331-335) are a series of polychlorinated amino acid derivatives from Pacific Island collections of D. herbacea. The structures were determined by X-ray analyses and the absolute configurations were determined by X-ray crystallography of a brominated derivative [301]. Herbamide A (336), a chlorinated amide was isolated from a Papua New Guinean sample of D. herbacea as a minor component [302]. D. herbacea from the southern Great Barrier Reef contained a thiazole (337) amongst other known metabolites [303]. A Dysidea sp. 

Athyl-/S./S-dinitroathyl-ather in Ger), (02N)2HC.H2C.0.C2H5 mw 164.12, N 17 07% colorless oil, bp 100° at 11mm press sol in org solvs v si sol in w was obtd on acidification if its Potassium salt, K.C4H7N205, It-yel ndls (from ale), prepd by reacting tri-nitroethane with K ethoxide forms a Bromine deriv, C Hy OjBr, col oil, bp 103-04° at 13mm press and a Silver salt, Ag.C Hy Oj, which is probably expl (See Refs)... 

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