Bromo-4-chlorophenol

Dichlorodibenzo- -dioxin. 2-Bromo-4-chlorophenol (31 grams, 0.15 mole) and solid potassium hydroxide (8.4 grams, 0.13 mole) were dissolved in methanol and evaporated to dryness under reduced pressure. The residue was mixed with 50 ml of bEEE, 0.5 ml of ethylene diacetate, and 200 mg of copper catalyst. The turbid mixture was stirred and heated at 200°C for 15 hours. Cooling produced a thick slurry which was transferred into the 500-ml reservoir of a liquid chromatographic column (1.5 X 25 cm) packed with acetate ion exchange resin (Bio-Rad, AG1-X2, 200-400 mesh). The product was eluted from the column with 3 liters of chloroform. After evaporation, the residue was heated at 170°C/2 mm for 14 hours in a 300-cc Nestor-Faust sublimer. The identity of the sublimed product (14 grams, 74% yield) was confirmed by mass spectrometry and x-ray diffraction. Product purity was estimated at 99- -% by GLC (electron capture detector). 

DCDD can be synthesized by two methods. In the first method, 2-bromo-4-chlorophenol and potassium hydroxide are dissolved in methanol and evaporated to dryness. The residue is then mixed with bis(2-ethoxyethyl) ether, ethylene diacetate, and a copper catalyst and then heated, cooled, and eluted from a chromatographic column with chloroform. This residue is evaporated and then sublimed. DCDD can also be synthesized by heating the potassium salt of 2,4-dichlorophenol in the presence of copper powder in a vacuum sublimation apparatus (IARC 1977). 

Bromine (165 g., 1.03 moles) is added slowly with stirring at room temperature to a solution of 128.5 g. (1.00 mole) of p-chlorophenol in 800 ml. of carbon tetrachloride. (Hood.) The mixture is allowed to stand overnight, and the solvent is removed by distillation. The residue is extracted with aqueous sodium hydroxide solution. Acidification of the aqueous extracts and distillation of the precipitated oil give a 62% yield of 2-bromo-4-chlorophenol boiling at 121-123°/10 mm. and melting at 33-34°. 

C6H4BrCfO 2-bromo-4-chlorophenol 695-96-5 25.00 1.7076 2 6521 C6H4FN03 2-fluoro-4-nitrophenol 403-19-0 25.00 1.4306 2... 

A solution of 2-bromo-4-chlorophenol (4 mmol) CH3O Cl in THF was cooled to -78°. A solution of... 

Bromo-2-chlorophenol, see Profenofos 2-Bromo-3-chloropropanol, see l,2-Dibromo-3-... 

Photolytic. When profenofos in an aqueous buffer solution (pH 7.0) was exposed to filtered UV light (X >290 nm) for 24 h at 25 and 50 °C, 29 and 56% decomposed, respectively, to 4-bromo-2-chlorophenol and 4-bromo-2-chlorophenyl ethyl hydrogen phosphate. Both compounds were also identified in soil irradiated with UV light. 

CeHeCIO a-Chlorophenol 175.5 C7H7Br o-Bromo toluene 181.75 CioHn d-Limonene 177.8 Nonazeotrope 243... 

Poly(oxy-1,4-phenylene) is obtained by electrooxidative polymerization of / -bromo-phenol in aqueous NaOH solution. The yield increases when aqueous NaOH is replaced by aqueous KOH or when the reaction is conducted at higher temperature. In contrast, p-chlorophenol electrooxidatively dimerizes to give the biologically and pharmacologically important dioxin, 2,7-dichlorodibenzo[, ][l,4]dioxine254. In an effort to find protective chemical coatings, electrooxidative polymerization of ra-chlorophenol and ra-bromophenol was observed255. 

Hart and Cassis, Jr. utilized the dechlorination with Raney alloy and alkali in the synthesis of 2,6-di-r-butylphenol from 4-bromo- or 4-chlorophenol as starting mate-... 

A comparison between the photoreactions of 2-chlorophenol and 2-bromo-phenol in a low-temperature argon matrix was carried out by Akai et al. by means of IR spectroscopy [17,18]. The formation of fulvene 6-oxide was evidenced in both systems. Homolytic C - Br cleavage was found as an additional pathway in the case of 2-bromophenol. 

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. 

C6H4BrCIO 4-bromo-2-chlorophenol 3964-56-5 20.00 1.6170 1 6520 C6H4FN03 3-fIuoro-4-nitrophenol 394-41-2 25.00 1.4306 2... 

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). 

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