Hydrobromio acid

This acid mixture may be prepared (compare Section 11,49, 1) by placing 120 g. (37-5 ml.) of bromine and 130 g. of crushed ice in a 500 ml. flask, cooling the latter in ice, and passing sulphur dioxide (from a siphon of the liquefied gas) into the bromine layer at such a rate that the gas is completely absorb. The flask is shaken occasionally, and the flow of gas is stopped inunediately the red colour due to free bromine has disappeared the mixture will then have a yellow colour. The resulting acid mixture is equivalent to 260 g. of 48 per cent, hydrobromio acid to which 75 g. of concentrated sulphuric acid have been added it need not be dis. tilled for the preparation of n-butyl bromide. 

Owing to the comparatively negligible difference in the cost of bromine and the equivalent quantity of constat boiling point hydrobromio acid, there is little to be gained—apart from the instructional value—in preparing the hydrobromio acid from bromine in the preparation of alkyl bromides. 

The mixed aliphatic - aromatic ethers are somewhat more reactive in addition to cleavage by strong hydriodio acid and also by constant b.p. hydrobromio acid in acetic acid solution into phenols and alkyl halides, they may be bromi-nated, nitrated and converted into sulphonamides (Section IV,106,2). 

It unites directly with hydriodic and hydrobromio acids when they are presented to it in the nascent state, forming compounds isomorpbous with the corresponding substances in the nitrogen series —... 

Ring cleavage of 1,2-dihydronaphthalene oxideM<1 and 1.4-dihydronaphthalene oxide 1 has been carried out with hydrochloric acid and hydrobromio acid respectively. Though it is Bafe to suppose a trarw-Mohydrin to have been formed in the second case (Eq. 726). the product stereochemistry is somewhat in doubt in the first Eq. 726). 

Keeently Bordwell and Pitt proposed an excellent method tor the ( ihMia of thietane from trunethylene chlorobioncude. The latter ia prepared indnstrially by the addition of hydrobromio acid to allyl chlonde in the preeenoe of a peroxide -which onenia the fixation of the htomine atom to the end of the chain. 

A considerable quantity of constant boiling point hydrobromio acid may be obtained by distilling these solutions. 

Chemical.—The chemical characters of Br are similar to those of Cl, but less active. With HsO it forms a crystalline hydrate at 0 (33° F.) Br 5HjO. Its aqueous solution is decomposed by exposure to light, with formation of hydrobromio acid. 

I hMphmium Cbmp(wnbasic properties, combining with hydriodioand hydrobromio acids to form definite salts, produced when the two dry gases are brought... 

Cleavage with pyridine-hydrochloric acid, glacial acetic acid, hydrobromio acid or dioxon-hydrochloride has been employed as methods of cleavage of oxirane rings before their determination [126]. 

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