2.3.4- Tribromophenol

Data Base, Jan. 2001 1 -hydroxy-2,4,6-tribromobenzene FLUKA CHEMIE 

Microbicide group (substance class) Chemical name Chemical formula Structural formula 

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It should be noted that phenol also reacts very readily with bromine to give the corresponding 2.4,6-tribromophenol, C6H2(OH)Br,v... 

Group III. Carboxylic and sulphonic acids (also sym.-tribromophenol, 2 4-dinitrophenol and picric acid) are also soluble in dilute sodium bicarbonate solution. 

Brominated Phenols. Tribromophenol [75-80-9] and dibromophenol [615-58-7] are both prepared through bromination of phenol. These are not actually used as reactive flame retardants, but rather as starting materials for other flame retardants such as BTBPE [37853-59-1] and epoxy oligomers. 

Bromination can be conveniently effected by transfer of bromine from one nucleus to another. As the Friedel-Crafts isomerization of bromoaromatic compounds generally takes place through an intermolecular mechanism, the migrating bromine atom serves as a source of positive bromine, thus effecting ring brominations (161,162). 2,4,6-Tribromophenol, for example, has been prepared by bromination of phenol with dibromobenzene. 

During certain substitution reactions, the carboxyl group is often replaced by the entering group. An example is fuming nitric acid, which results in the formation of trinitrophenol. Another is the bromination of saUcyhc acid in aqueous solution to yield 2,4,6-tribromophenol [25376-38-9] (eq. 6). 

Oxidation of saligenin with chromic acid or silver oxide yields saUcyladehyde as the first product. Further oxidation results in the formation of sahcyhc acid, which is also obtained when saligenin is heated with sodium hydroxide at 200—240°C. Chlorination of an aqueous solution of the alcohol gives 2,4,6-trichlorophenol, and bromination in an alkaline medium yields 2,4,6-tribromophenol and tribromosaligenin. When saligenin is heated with one mole of resorcinol in the presence of anhydrous zinc chloride, 3-hydroxyxanthene forms. 

Phenols and phenol ethers readily undergo mono-, di-, or trihromination in inert solvents depending on the amount of bromine used. In water the main product is the 2,4,6-tribromophenol [118-79-6] C H Br O (23). In water or acetic acid anilines also give the tribrorninated product (25). 

Tribromophenol can be further brominated in buffered acetic acid to give 2,4,4,6-tetrabromo-2,5-cyclohexadien-l-one [20244-61-5] a useful hrominating agent (26). 

A small amount of tribromophenol is eliminated in the evaporation, the substance being volatile with steam. 

Tribromophenol [118-79-6] M 330.8, m 94", pK 6.00. Crystd from EtOH or pet ether. Dried under vacuum over P2O5 at room temperature. 

Treatment of p-hydroxybenzoic acid with aqueous bromine leads to the evolution of carbon dioxide and the formation of 2,4,6-tribromophenol. Explain. 

Add to another portion a drop of bromine water. A white crystalline precipitate of tribromophenol is formed. 

Tartaric acid, 114 Terephthalic acid, i7r Tetrabromocresol, 165 7 hiocarbamide, 128 Thiocarbanilamide, 159 Thiocarbanilide, 159 Thiourea, 128 /i-Tolyl bromide, 167 / Tolyl chloride, 165 /-Tolyl cyanide, 169 Tolyliodochloride, 169 Toluene from toluidine, 163 / Toluic acid, 170 Tribromophenol, 180 Trichloracetic acid, 99 Trimethylxanthine, 131 l rinitrophenol, 185 Triphenylguanidine, ito Triphenylmetbane, 2 4 J schugac s hydroxyl method, 223 Tube furnace, 23 Tyrosine, 133... 

In the presence of excess bromine, the first-order rate coefficient was 10.3 x 10" 5, but kinetic studies here were complicated due to rapid reaction of bromine with the 2,4,6-tribromophenol to give the intermediate (LXII), with SO3 replaced by Br) which slowly decomposed with a rate coefficient k2 to give two products. By analysis in terms of two consecutive first-order reactions, the values of k2 and k2 were determined as 9.2 x 10"5 and 3.75 x 10"4 and the latter rate being the faster means that two moles of bromine were consumed for every mole of sulphonate undergoing substitution in fact, more than two moles were consumed, the reason for this being undetermined. 

A. 2,i,l,()-Tetrabromo-2,5-cyclohexadien-l-one. A mixture of 66.2 g. (0.2 mole) of 2,4,6-tribromophenol (Note 1), 27.2 g. (0.2 mole) of sodium acetate trihydrate, and 400 ml. of glacial acetic acid is placed in a 1-1. Erlenmeyer flask and warmed until a clear solution is obtained. The temperature of the solution is approximately 70°. The solution is magnetically stirred and cooled to room temperature to produce a finely divided suspension of the phenol. A solution of 32 g. (0.2 mole) of bromine in 200 ml. of glacial acetic acid is added dropwise over 1 hour (Note 2). The resulting mixture is kept at room temperature for 30 minutes and is then poured onto 2 kg. of crushed ice. The yellow solid which separates is removed by suction filtration after the ice has melted, and the damp crystals are dissolved in the minimum quantity of warm chloroform (Note 3). The upper aqueous layer is removed by means of a pipet fitted with a suction bulb. The dienone crystallizes from the... 

The submitters used reagent-grade 2,4,6-tribromophenol. The checkers recrystallized the practical-grade reagent purchased from Fisher Scientific Company. The solvent used was Skelly B, and the melting point of the phenol, after recrystallization, was 93-95°. 

Tribromophenol may be recovered by acidification of the aqueous alkaline extracts and can be reapplied in the preparation of the tetrabromo-compound after crystallization from petroleum ether (b.p. 80-100°). 

Addition of every primary amine was effective for obtaining the ortho-dibromide selectively. In the absence of amines, the yield of 2,6-dibromophenol was much lower than that of 2,4,6-tribromophenol. The selective ortho-dibromination of phenols was also observed when secondary amines were added. 

The phenol-contaminated sample was unique in yielding bromine containing none of the starting contaminant. Analysis of the bromine by FT-IR and INMR showed a complex mixture of brominated phenols and small amounts of other brominated hydrocarbons. The absence of phenol in the bromine product is not surprising, since phenol reacts with bromine at room temperature to make predominantly tribromophenol. 

For the organic contaminants, the required bromine product quality wilt also be site specific. If the catalytic oxidation unit is dedicated to a single bromination process, phase separation and drying may be the only purification required. Contaminants in the recovered bromine which are either the starting materials or products of the original bromination reaction should not present a problem if present in bromine recycled to the bromination reactor. In this case, the catalytic reactor would be operated to minimize the formation of undesirable brominated byproducts. For example, if phenol is present in the waste HBr from a tribromo-phenol manufacturing process, minor tribromophenol contamination of the bromine recycled to the reactor should not be a problem. Similarly, fluorobenzene in bromine recycled to a fluorobenzene bromination process should not present a problem. 

Tribromophenol and other simple brominated phenols (No. 66, 2005) Tributyltin oxide (No. 14, 1999)... 

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. 

Boyle AW, CD Phelps, LY Young (1999) Isolation from estuarine sediments of a Desulfovibrio strain which can grow on lactate coupled to the reductive dehalogenation of 2,4,6-tribromophenol. Appl Environ Microbiol 65 1133-1140. 

They are soluble in 6 per cent, sodium hydroxide solution and insoluble in 5 per cent, sodium bicarbonate solution they are precipitated from their solutions in aqueous sodium hydroxide by carbon dioxide. [Exceptions the presence of certain negative groups in phenols increases the acidity to such an extent that they may dissolve in sodium bicarbonate solution, for example, 2 4-dinitrophenol, picric acid and s-tribromophenol.]... 

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