Bromide solution

Addition of chlorine water to a bromide solution liberates bromine, which colours the solution brown. 

SO, + 2H,0 + Br, — HjSO, + 2HBr Alternatively, the acid mixture may be obtained from the reaction between potassium bromide solution and concentrated sulphuric acid below 76° the potassium hydrogen sulphate crystallises out and is removed by filtration ... 

Prepare a solution of p-tolyldiazonium chloride from 53 -5 g. of p-tolui-dine using the proportions and experimental conditions given under p-Chlorotoluene (Section IV,61). Add the diazonium chloride solution to the boiling cuprous bromide solution, and proceed as in Method 1. The yield of pure, colourless p-bromotoluene, b.p, 182-184° (mainly 183°), is 40 g. m.p. 26°,... 

Mercuric Bromide. Mercuric hi.omide[7789-94-7] HgBr2 is a white crystalline powder, considerably less stable than the chloride, and also much less soluble in water (0.6% at 25°C). Therefore, it is prepared easily by precipitation, using mercuric nitrate and sodium bromide solution. Drying of the washed compound is carried out below 75°C. Mercuric bromide has a few medicinal uses. 

Boiling the solution speeds the conversion of intermediate hypobromites and bromites to bromate. The less soluble bromate can be separated from the hahde by fractional crystallization. A method that is often more economical is the oxidation of bromides into bromates by hypochlorites in aqueous solution. This can be done by passing chlorine into an alkaline bromide solution (75) ... 

Other Metals. Ruthenium, the least expensive of the platinum group, is the second best electrical conductor, has the hardest deposit, and has a high melting point. A general purpose bath uses 5.3 g/L of mthenium as the sulfamate salt with 8 g/L sulfamic acid, and is operated at 25—60°C with a pH of 1—2. Osmium has been plated from acid chloride solutions (130) and iridium from bromide solutions, but there are no known appHcations for these baths. 

Environment Internal Untreated water at 42°F (6°C) External Lithium bromide solution at 40°F (4°C) and a partial pressure of 4 mm of mercury... 

The preparation of cyclohexylmagnesium bromide is described on p. 22. The solution may be standardized by titrating against 0.5 N hydrochloric acid, and exactly one mole equivalent is used in the preparation. Five cubic centimeters of cyclohexylmagnesium bromide solution is slowly added to 20 cc. of water, an excess of the standard acid is added, and the excess acid titrated with sodium hydroxide. If 85 g. (3.5 moles) of magnesium, one liter of dry ether, and 571 g. of cyclohexyl bromide (3.5 moles) are used, a solution results which is about 2 molar. 

In a 5-I. round-bottom flask, fitted with a stirrer, separatory funnel and a reflux condenser to the upper end of which a calcium chloride tube is attached, is placed 150 g. of magnesium turnings. A small crystal of iodine (Note i) and about 100 cc, of a mixture of 822 g. (6 moles) of M-butyl bromide and 2 1. of anhydrous ethyl ether are added. As soon as the reaction starts, 350 cc. of anhydrous ether is added and the remainder of the -butyl bromide solution is dropped in at such a rate that the mixture boils continuously. The time of addition (one and one-half hours) may be decreased by cooling the flask externally. Stirring is started as soon as enough liquid is present in the flask. 

The butyl bromide appears to react as fast as it is added, so that there is no need of stirring or warming the butylmag-nesium bromide solution before adding the ethylene oxide. The small amount of unattacked magnesium has no influence on the subsequent reactions. 

Tetrahydrofuran, anhydrous, 99.9t (water content <0.006t) was purchased from Aldrich Chemical Company, Inc., and used as received. The vinyl bromide solution was prepared In a 500-mL, round-bottomed flask fitted with a glass stopper. The stoppered flask containing the tetrahydrofuran was chilled to about 5 C and weighed. The vinyl bromide, also chilled to about 5°C, was rapidly poured Into the tetrahydrofuran until the desired amount had been added. The flask was stoppered, the contents mixed by shaking, allowed to warm to about 16°C, and then added to the pressure-equalizing addition funnel. 

In a i-l. round-bottomed, three-necked flask fitted with an efficient reflux condenser, liquid-sealed stirrer, and dropping funnel is placed t3 g. (0.53 gram atom) of magnesium turnings. A few cubic centimeters of a solution of 60 g. (41.4 cc., 0.55 mole) of pure ethyl bromide in 50 cc. of absolute ether is added and the stirrer started (Note i). When the bromide begins to react 200 cc. of absolute ether is added, and then the balance of the bromide solution is run in as fast as the refluxing permits (about one-half hour). After allowing fifteen minutes for the completion of the reaction, a solution of 40 g. (0.42 mole) of 2,4-dimethyl-pyrrole (Org. Syn. 15, 20) in 100 cc. of absolute ether is added in the course of twenty minutes (Note 2) and the mixture is refluxed for one-half hour on the steam bath. 

Alkyl fluorides have been prepared by reaction between elementary fluorine and the paraffins, by the addition of hydrogen fluoride to olefins, by the reaction of alkyl halides with mercurous fluoride, with mercuric fluoride, with silver fluoride, or with potassium fluoride under pressure. The procedure used is based on that of Hoffmann involving interaction at atmospheric pressure of anhydrous potassium fluoride with an alkyl halide in the presence of ethylene glycol as a solvent for the inorganic fluoride a small amount of olefin accompanies the alkyl fluoride produced and is readily removed by treatment with bromine-potassium bromide solution. Methods for the preparation of alkyl monofluorides have been reviewed. ... 

J/3,5a,6(3- Trihydroxy-6oi, 17a-Dimethyl-17 -Carbometboxyandrostane (IV) 3(3-Acetoxy-5a-hydroxy-17a-methyl-17/3-carbomethoxyandrostan-6-one (III, 1.004 g) is dissolved in dry benzene (25 ml) and methyl magnesium bromide solution in ether (3M, 10 ml) is added. 

Alternatively, 25.0 g of either 3j3,5a-dihydroxy-17a-methyl-17j3-carbomethoxyandrostan-6-one (Ilia) or 25.0 g of its 3)3-acetate (Hlb), are dissolved in dry tetrahydrofuran (1,250 ml, freshly distilled over lithium aluminum hydride) and dry benzene (2,000 ml) is added. Methyl magnesium bromide in ether solution (3 M, 750 ml) is added to the stirred solution and the resulting mixture is stirred at room temperature for 16 hours. An additional quantity of methyl magnesium bromide solution in ether (2M, 375 ml) is added, and 1,250 ml of the solvent mixture are distilled off. The resulting mixture is refluxed for 5 hours and worked up as described above, yielding compound (V) as a colorless oil. 

Mixing Chart for Zinc Brotnide/Calciutn Bromide Solution Biend 13.7 lb/g l CaBr2/CaCl2-t-19.2 Ib/gal ZnBr2/CaBr2... 

Absorption-type refrigerators operating with strong lithium bromide solutions can also be inhibited by a number of chemicals. Thus, a mixture of lithium hydroxide -I- BTA -I- sodium molybdate has been reported . 

Bromides can also be determined by the Volhard method, but as silver bromide is less soluble than silver thiocyanate it is not necessary to filter off the silver bromide (compare chloride). The bromide solution is acidified with dilute nitric acid, an excess of standard 0.1M silver nitrate added, the mixture thoroughly shaken, and the residual silver nitrate determined with standard 0.1 M ammonium or potassium thiocyanate, using ammonium iron(III) sulphate as indicator. 

To 25.0 mL of 0.01-0.015 M persulphate solution in a 150 mL conical flask, add 7 mL of 5 M sodium bromide solution and 2 mL of 3 M sulphuric acid. Stopper the flask. Swirl the contents, then add excess of 0.05M ammonium iron(II) sulphate (15.0mL), and allow to stand for 20 minutes. Add 1 mL of 0.001 M ferroin indicator, and titrate the excess of Fe2+ ion with 0.02 M cerium(IV) sulphate in 0.5 M sulphuric acid to the first colour change from orange to yellow. 

As an alternative, a reversible indicator may be employed, either (a) 1-naphthoflavone (0.5% solution in ethanol, which gives an orange-coloured solution at the end-point), or (b) p-ethoxychrysoidine (0.1% aqueous solution, colour change pink to pale yellow). Under these conditions, the measured 25 mL portion of the arsenic solution is treated with 10 mL of 10 per cent potassium bromide solution, 6 mL of concentrated hydrochloric acid, 10 mL of water and either 0.5 mL of indicator (a) or two drops of indicator (b). 

Reagent. Supporting electrolyte. Prepare a 0.05 M sodium bromide solution. 

Procedure. Place 80 mL of the arsenic/antimony solution in the titration cell of the spectrophotometer. Titrate with standard bromate/bromide solution at 326 nm taking an absorbance reading at least every 0.2 mL. From the curve obtained calculate the concentration of arsenic and antimony in the solution. 

When 1-methyl-, 1,2- and 1,3-dimethyl-indoles were oxidized on a platinum electrode in methanolic ammonium bromide solution, in addition to the oxidation products, products of nuclear bromination at the 3-and 5-positions were observed. 1,2- Dimethylindole (20) gave 3-bromo-1,2-dimethylindole (81CCC3278) [bromine in chloroform gave the same product (85CHE786)]. In acidic conditions the amidinium cation formed from 20 was brominated in the 5-position (Scheme 14). Acylated 2-aminoindoles reacted similarly in neutral media to give 3-bromo derivatives and when protonated to give 5-bromo products. Bromine in chloroform transformed l-methyl-2-dimethylaminoindole (21) into the 3-bromo derivative (85CHE782) (Scheme 15). 

The arylation of alkenes by treatment with a diazonium chloride (or bromide) solution and cupric chloride (or bromide) is called the Meerwein arylation reaction, after its discoverer (Meerwein et al., 1939). Originally, it was discovered using a,P-unsaturated carbonyl compounds, namely coumarin (Scheme 10-43) and cinnamic derivatives (Schemes 10-44 and 10-45). As Scheme 10-45 shows, the Meerwein reac-... 

Recycle traditionally involves caustic scrubbing the gaseous HBr from bromination reactions (eqn. 3). The resulting sodium bromide solution is then treated with chlorine gas to generate bromine (eqn. 4). 

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