Bromic acid, reactions

CH3C(0)CH2Br. Colourless liquid which rapidly becomes violet in colour it is a powerful lachrymator b.p. 1367725 mm. Manufactured by treating aqueous propanone with bromine at 30-40 C it is usual to add sodium chlorate(V) to convert the hydro-bromic acid formed by the reaction back to bromine. It is not very stable and decomposes on standing. 

Acetophenone.—The Fnedel-Crafts reaction, of which this pieparation is a type, consists in the use of anhydious aluminium chlonde for effecting combination between an aromatic hydrocarbon or its deiivative on the one hand, and a halogen i,Cl 01 Bi) compound on the othei. The leaction 13 always accompanied by the evolution of hydiochloiic or hydio-bromic acid, and the product is a compound with AlCl-j, which decomposes and yields the new substance on the addition of watei. This reaction has been utilised, as in the present case, (r) for the prepaiation of ketones, in which an acid chloiide (aliphatic or aromatic) is employed,... 

The initial study by Berliner369 used R = Me, R = H, and R" variable, the reaction being carried out in a refluxing mixture of acetic acid (10 ml), hydro-bromic acid (4 mole, 48 %) and water (1 ml). The rate coefficients (the reaction was first-order in aromatic) are given in Table 95 and it appeared that the reaction... 

Bromates, chlorates or iodates ignite in contact with phosphonium iodide at ambient temperature if dry, or in presence of acid to generate bromic acid, etc. Ignition also occurs with nitric acid, and reaction with dry silver nitrate is very exothermic. Interaction with antimony pentachloride at ambient temperature proceeds explosively. 

C. 3,5-Dibromosulfanilamide. The bromination of sulfanilamide is carried out in much the same way as the chlorination. The stirrer must be more efficient (Note 9) a glass stirrer with two sets of blades is satisfactory if run at high speed. Fifty grams (0.29 mole) of sulfanilamide is dissolved in a mixture of 850 ml. of water (Note 9) and 100 ml. (0.68 mole) of 40% hydro-bromic acid (Note 10). The solution is heated as above, but to 70-75°, and 65 g. (59 ml., 0.58 mole) of 30% hydrogen peroxide is added (Notes 2 and 11). A precipitate settles in 2 to 3 minutes, and the solution becomes yellow. The heat of reaction causes the internal temperature to rise without further application of heat to a maximum of 85-90° after 10 minutes by the end of the reaction time the temperature will have fallen to about... 

A. J. Balard showed that bromic acid is decomposed by hydrobtomic add into bromine and water by hydrochloric acid into water an d bromine chloride and by hydriodic acid into water and iodine bromide. There are nine reactions belonging to this set, namely, chloric, bromic, and iodic acids each with each of the three haloid acids—HC1, HBr, and HI. The kinetics of these reactions have been studied extensively.29 W. Bray has shown that the velocity of the reaction between... 

Preparation of bromine by oxidizing hydro-bromic acid by manga-nese(IV) oxide Drawing of apparatus. Reaction equations. Required calculations. Tabulated data (b.p. of bromine, density, etc.) When the reaction mixture is heated, a brown bromine vapour condensing as a heavy reddish brown liquid evolves... 

Prepare a little of a bromic acid solution. To do this, mix 2-3 drops of a saturated potassium bromate solution with 1-2 ml of a dilute sulphuric acid solution. Throw a minute iodine crystal into the solution, mix the test tube contents several times, decant the solution, and add several drops of an organic solvent to it. What is observed Write the equations of the reactions. Will bromine displace iodine from iodic acid ... 

The hydroxy groups of pyrrolizidine amino-alcohols are readily replaced by chlorine atoms upon treatment with thionyl chloride (see, e.g., refs. 101 and 103). In this reaction, the allylic hydroxyl group is more reactive and can be selectively replaced by chlorine.79 In some particular cases, methoxyl groups can also be substituted for halogen e.g., l/3-methoxymethyl-8a-pyrrolizidine, when treated with hydro-bromic acid, gives rise to the corresponding bromo derivative.104... 

Now that we know the names and formulas of some acids and bases, we can also write equations for specific examples of this type of reaction, using our shorthand notation. For example, if potassium hydroxide reacts with hydro-bromic acid, we write... 

The oxidation of arsine may be accomplished by means of the halogen oxyacids and their salts,8 although not so readily as with the halogens themselves. Hypochlorites and hypobromites cause complete oxidation to arsenic acid, but side reactions are liable to occur, especially if the gas is present in excess. Chloric add slowly oxidises arsine to arsenious acid a trace of silver nitrate catalyses the reaction. Chlorates are quite inactive. More complete oxidation results with solutions of bromic acid and bromates, iodic acid and iodates, especially in the presence of catalysts. The reactions are of the type represented by the equation8... 

Arsenious oxide and arsenites may be oxidised similarly by bromine or bromic acid. In hydrochloric acid solution the reaction with bromine may be represented by the equation... 

It has been reported (Bruno Camerino, private communication) that, during the preparation of sodium nitromalonaldehyde monohydrate1 on a pilot-plant scale, two operators were so affected by the fumes evolved during the preparation that their immediate hospitalization was necessary. It was determined subsequently that hydrogen cyanide, up to approximately 1 g./kg. of muco-bromic acid utilized, was formed in the reaction mixture. It is essential that precautions specified in Note 1 of the procedure be followed carefully. 

In this section, consideration will be given to the actual processes of acetal- or ketal-formation and not to the more indirect methods by which acetals and ketals of the polyhydric alcohols may be synthesized from compounds (e.g. derivatives of the monosaccharides) containing preformed alkylidene or arylidene groupings. The condensation of a carbonyl compound with a glycol is facilitated by acidic catalysts, and, since the reaction is reversible, by dehydration. The catalysts most frequently employed are concentrated sulfuric, hydrochloric and hydro-bromic acids, gaseous hydrogen chloride, zinc chloride and cupric sulfate others are phosphorus pentoxide, sulfosalicylic acid, and anhydrous sodium sulfate. The formation of benzylidene compounds is promoted less efficiently by phosphorus pentoxide than by either concentrated sulfuric acid or concentrated hydrochloric acid 1" the reaction is assisted by chloro- and nitro-substituents on the aromatic nucleus, but hindered by methyl- and methoxy-groups.18... 

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