Water bromine

Aniline is readily halogenated, treatment with bromine water giving an instant precipitate of 2,4,6-tribromoaniline. 

Bromine. Slip slightly to one side the glass plate covering one jar of ethylene, add 2-3 ml. of bromine water (preparation, p. 525), restore the glass plate in position, and then shake the jar vigorously. The colour of the bromine rapidly disappears as 1,2-dibromoethanc is formed. Note that owing to the absorption... 

Bromine. Slip the glass cover of a jar momentarily aside, add 2-3 ml. of bromine water, replace the cover and shake the contents of the jar vigorously. Note that the bromine is absorbed only very slowly, in marked contrast to the rapid absorption by ethylene. This slow reaction with bromine water is also in marked contrast to the action of chlorine water, which unites with acetylene with explosive violence. (Therefore do not attempt this test with chlorine or chlorine water.)... 

Certain phenols give white bromo derivatives with bromine water. 

Action of bromine water. To a concentrated aqueous solution of the phenol or to the phenol itself, add bromine water gradually. At first the bromine is decolorised and then on adding an excess a white or yellowish-white precipitate of a polybromo-derivative is produced with all except catechol, hydroquinone, i- and 2 naphthol. 

On adding i drop of bromine water to catechol, a deep red coloration is produced immediately. On gradually adding bromine water to a solution of hydroquinone, a deep red coloration is produced, followed by the separation of deep green crystals which then dissolve giving a yellow solution, i- and 2-Naphthol will decolorise hromine water, but usually no precipitate of the bromo compound can be obtained. 

Formation of bromostyrene. Dissolve 0-2 g. of cinnamic acid (or a cinnamate) in about 5 ml. of NagCOg solution. Add bromine-water drop by drop and note the rapid separation of bromostyrene, CjHjCHiCHBr, as a colourless oil, having a pleasant characteristic odour. 

Bromine-water. Shake about 5 ml. of bromine with 100 ml. of water, and decant off the clear aqueous solution as required (concentration about 3%). 

The hypobromite solution may be prepared by treating 6 ml. of bromine water with dilute sodium hydroxide solution dropwise, until the bromine colour is just discharged. 

Extract the acidified solution with ether, remove the ether and identify the phenol in the usual manner (see Section IV,114).f Add a few drops of bromine water or nitric acid to the aqueous layer and test for sulphate with barium chloride solution. 

Dissolve the solid in 700 ml. of water in a 1500 ml. round-bottomed flask, and add a solution of 88 ml. of concentrated sulphuric acid in about 200 ml. of water until the liquid has a distinct odour of sulphur dioxide sufficient heat will be liberated in the neutralisation to cause the solution to boil. Immediately steam distil the liquid (Fig. II, 40, 1 it is better to use the apparatus shown in Fig. II, 41, 3) until a sample of the distillate gives only a slight precipitate with bromine water. About 700 ml. of distillate should be collected. Saturate the steam distillate with salt, extract the dl with ether, dry the extract with a little anhydrous magnesium or calcium sulphate, distil oflF the ether (compare Fig. II, 13, 4, but with a 50 ml. Claisen flask replacing the distilling flask) and distil the residue under diminished pressure. Collect the p-cresol at 95-96°/15 mm. the colourless liquid solidifies to a white crystalline solid, m.p. 31°. The yield is 24 g. 

Dissolve 0 -1 g. of the compound in 10-15 ml. of water and add bromine water until the colour of the latter persists. A white precipitate will form if a phenol is present. 

Bromine in carbon tetrachloride and bromine water, (c) Ferric chloride solution. 

Sn Citrate, C20 , 2,3-dimercaptopropanol, EDTA, F , E, OH , oxidation with bromine water,... 

Bromine water, saturated solution to 400 mL water add 20 mL of bromine use a glass stopper coated with petrolatum. 

Acids nd Sa.lts. The oxygen acids of bromine are strong oxidants but at ordinary temperatures are stable only in solution. An aqueous solution of hypobromous acid [13517-11-8] may be prepared by treating bromine water with silver oxide or mercuric oxide (69) ... 

Orotic acid undergoes 5-nitration, 5-bromination in hydrobromic acid with peroxide, 5,5-dibromination following decarboxylation in bromine water, esterification, methylation (rather complicated), conversion into its acid chloride (containing some anhydride) by treatment with thionyl chloride, and conversion into 2,6-dichloropyrimidine-4-carboxylic acid by phosphoryl chloride (62HC(16)422). 

Ethylene bromohydrin has been prepared by the reaction between ethylene glycol and hydrobromic acid and phosphorus tribromide. It has also been prepared by the direct addition of hypobromous acid to ethylene, and by the reaction between ethylene and dilute bromine water. With ethylene oxide now available at a reasonable price, the method described is probably the best because of the high yields and the convenience of reaction. 

The cream-colored solid is separated at once by filtration and washed thoroughly with water to remove excess bromine water and acids. It is used in the next step without drying. The melting range of the crude product is usually 170-172°. 

Reaction.—Add bromine water to a little of the allyl alcohol. It is immediately decolouiised, C3H3OH + Br3 = CjH3lii30H. See Appendix., p. 259. 

Pure Commercial Benzene, obtained from coal-tai naphtha, should distil w lthin one degiee (80—Si ), and solidify completely when cooled to 0°. Other tests are as follow s shaken with concentrated sulphuric acid for a few minutes, the acid should not darken, and a drop of bromine water should not be immediately decolourised. A single distillation over a few small pieces of sodium, which absorb any traces of water, is usually a sufficient purification. If the benzene impart a brown or black colour to the sulphuric acid, it must be repeatedly shaken with about 20 per cent, of the acid until the lattev becomes only slightly yellow on standing. This is done in a stoppered separating funnel, and after shaking fora few minutes the mixture is allow ed to settle, and the low er layer of acid diawn off. The benzene is then shaken tw o 01 three times with water to free it from acid, carefully separated from the aqueous layer, and left in contact with fused calcium chloride until the liquid becomes clear. It is then decanted, frozen in ice, and any liquid (carbon bisulphide, paraffins) carefully drained off, and die benzene finally distilled over sodium. 

Rcarti(m< . — W . Vc a solution of / -tiesol by shaking up a few drops with 5 c.c. of water. I o one jKirlion add a few drops of bromine water. A rvhite preci[)itatc of letrabromocrcsol is formed. To another j)Ortion add a drop of feme chloiide. A blue colouration is produced. Sec Appendix, p. 284. 

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

The action of bromine water (p. 180), Liebermann s nitroso-reaction (p. 180) and the phenolphthalein reaction (p. 186), using rone, sulphuric acid or zinc chloride, may also be applied. 

Other routes are the thermal decomposition of (NH4)2Cr207, the reaction of NH3 with bromine water, or the high-temperature reaction of NH3... 

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