Chloro-4-bromophenol

Bromine (200 g., 1.25 moles) is slowly added with stirring to a solution of 150 g. (1.17 moles) of o-chlorophenol in 4 volumes of carbon tetrachloride. (Hood.) The mixture is allowed to stand overnight, and the solvent is then removed by distillation. Fractional distillation 

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Ci2H7MnOs, Tetracarbonyl-2-acetylphenylmanganese, 41B, 827 C12H8BrClHgO, (2-Chloro-4-bromophenolate)phenylmercury, 39B, 561 Cl2HioF2FeO, 1 (1,1-Difluoro-2-oxo-2-(cyclopentadienyliron)ethyl)-cyclopenta-2,4-diene, 42B, 627... 

Our method, NBS-amine system, is applied to orf/zo-bromination of 2-substituted phenols (e.g. 2-allyIphenol, o-cresol, 2-bromophenol, and 2-chloro-phenol) (Table 4). 

A spore-forming strain of Desulfitobacterium chlororespirans was able to couple the dechlorination of 3-chloro-4-hydroxybenzoate to the oxidation of lactate to acetate, pyruvate, or formate (Sanford et al. 1996). Whereas 2,4,6-trichlorophenol and 2,4,6-tribro-mophenol supported growth with the production of 4-chlorophenol and 4-bromophenol, neither 2-bromophenol nor 2-iodophenol was able to do so. The membrane-bound dehalogenase contains cobalamin, iron, and acid-labile sulfur, and is apparently specific for ortho-substituted phenols (Krasotkina et al. 2001). 

Chloro- and bromophenols and A -acylhaloanilines can be fluorinated in the ortho or para position by 1-fluoropyridinium triflates and the fluorophenols and iV-acylfluorohaloanilines thus obtained reduced to fluorophenols and iV-acylfluoroanilincs. For example, 4-chlorophenol reacts with 2-chloro-l-fluoro-6-(trichloromethyl)pyridinium tetrafluoroborate in 1,2-dichlo-roethane at 45°C for three hours to give 4-chloro-2-fluorophenol in 68% yield.51... 

Peters S, Spiteller P (2006) Chloro- and Bromophenols from Cultures of Mycena alcalina. J Nat Prod 69 1809... 

Phenyl ureas, carbamates, organochlorine insecticides, 4-bromophenol, captan, bromo- and chloroanilines, methylanilines, bromo- and chloro-nitrobenzenes, diphenyl amino folpet, hexachlorobenzene, naphthalene, phenol, simazine... 

Earlier studies [11,12] have shown that photo excitation of aqueous 2-chloro-phenol or 2-bromophenol leads to contraction of the aromatic cycle to give cyclopentadienic acids (an example of a Wolff rearrangement [13]), and to substitution of the halogen by OH (photohydrolysis), with moderate quantum yields (< = 0.01-0.04). A carbene (2-oxocyclohexa-3,5-dienylidene) was suggested as a possible intermediate in the ring contraction pathway [11]. 

The photochemistry of aqueous 2-iodophenol was the subject of a subsequent study [19]. Although ring contraction, carbene formation and photohydrolysis took place in this case too, they all were minor pathways (

comparison with homolytic C -1 cleavage forming phenyl radicals and I" atoms (

radical anions. It was concluded that the heterolytic dehalogenation mechanism observed for aqueous 2-chloro- and 2-bromophenol is overruled in the case of 2-iodophenol by a homolytic one promoted by the comparatively weaker carbon-halogen bond [19]. 

The effect of the halogen substituent (fluoro, chloro, bromo and iodo) on the yield and mechanism of 4-halophenol photolysis was investigated by Durand et al. [24], Transient spectroscopy in aerated aqueous solutions indicated the formation of p-benzoquinone O-oxide from each derivative except 4-iodophenol for which no transients were detected p-benzoquinone and hydroquinone were found as photoproducts for all four compounds. It was concluded that the carbene mechanism was valid for the whole series. Under continuous irradiation, the 4-halophenol degradation quantum yields were determined to be

fluorescence lifetimes decreased in the same order, from 2.1 ns for 4-fluorophenol to 0.4 ns for 4-chlorophenol and < 0.1 ns for 4-bromophenol. 

Comparison of the average geometrical parameters in o- and p-chloro and bromophe-nols is given in Table 6. The average bond angles in o-chlorophenols and o-bromophenols as well as the average bond angles in p-chlorophenols and p-bromophenols are the same. 

TABLE 6. Comparison of the average bond length (A) and bond angle (deg) at the hydroxyl group in o- and p-chloro and bromophenols (the notation is given in 48)... 

The diazine substrate was prepared by reaction of the oxyanion of 2-bromophenol with 2-chloro-l,3-diazine followed by palladium(0)-mediated coupling with (trimethylsilyl)ethyne. 

Nitroso compounds, suspended at room temp, in aq. hydroxylamine hydrochloride or sulfate, stirred and treated with finely powdered excess CuCl or CuBr, then with HCI (d. 1.18) or HBr (d. 1.7), yield halides.—E 3-Chloro-4-nitrosophenol — 3,4-dichlorophenol. Y 74.7%. —p-Nitrosophenol p-bromophenol. Y 84%. (F. e. s. H. H. Hodgson... 

Methylphenol in ethanolic solution treated with ferric nitrate nonahydrate (1 equiv.) and heated briefly for 30 sec. afforded an 83% yield of 4-methyl-2-nitrophenol. Under similar conditions 4-chlorophenol gave 4-chloro-2-nitrophenol (88%), 4-bromophenol gave 4-bromo-2-nitrophenol (64%) and 2-chlorophenol, a mixture of 2-chloro-4-nitrophenol (56%) and 2-chk>ro-6-nitrophenol (35%). Aluminium, chromium and copper(ll) nitrates were also used (ref.63). 

The most obvious taste and odor compounds, such as hydrocarbons, solvents, iodoforms, and various chloro- and bromophenols, which have odor thresholds in the microgram per liter range, are currently analyzed by GC-EI-MS using quadrupole instruments. 

Hanai et al. [895] generated k values for 43 alkanes, alkylbenzenes, chloro and polychlorinated benzenes, and 41 alkylphenols, chlorophenols, and bromophenols on a C 3 column using 60/40 to 90/10 acetonitrile/water mobile phases. Once again such a comprehensive tabulation of k values is extremely valuable for method development work. 

Bromo-2-chloro( 1 -octene-3-ones), 2889 (Z)-l-Bromo-l-chlorovinyl group, 980 Bromocresol (BC), 2884 Bromocryptine, 707 Bromodeoxyuridine, 1445 1 -Bromo-2,3-dichloro( 1 -octene-3-ones), 2889 Bromo-4-hydroxybenzaldehyde (BH), 2884 Bromoindole (BRI), 32, 33, 1212 Bromophenol (BP), 2884, 2905... 

Propoxyethanol 2-(2>Methoxyethoxy)ethano p-Bromochlorobenzene p-Dibromobensene m-Chloro nitrobenzene o-Chloronitrobenzene p-Chloronitrobeniene o-Dichlorobensene p-Dichlorobensene Bromobensene o-Bromophenol Chlorobeniene p-Chlorophenol lodobencene Nitrobenzene o-Nitrophenol... 

The decomposition of benzene and naphthalene and its homologues by microorganisms has already been discussed earlier. The metabolizing mechanisms of naphthalenes in fish have been well studied [47, 49]. Decomposition products of chlorobenzene in daphnia, mosquitos, snails and fishes are the polar compounds chlorophenol and chloro-o-dihydroxybenzene amongst other compounds, those of nitrobenzene aniline, acetanilide, aminophenols and nitrophenols and those of hexachlorobenzene pentachlorophenol and unknown compounds [71]. Bromoben-zene is deactivated to the toxic bromophenol [217]. In the case of man and land mammals, studies have concentrated on the metabolism of benzene, toluene, xylenes and styrene, which are also significant in occupational medicine [12, 13, 136, 195, 196, 215-217], A comparison of the metabolism of benzene into phenol in various animal species with the aid of microsomal preparations of the lungs or liver yielded vast differences. However, it is possible for benzene, in part, to inhibit or prevent its own metabolism [218]. 

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