These compounds may be obtained by heating the alkylen iodides or bromides (e.g.
The oxychloride, bromides, and other compounds were subsequently discovered; here we need only notice Moissan's preparation of the trifluoride and Thorpe's discovery of the pentafluoride, a compound of especial note, for it volatilizes unchanged, giving a vapour of normal density and so demonstrating the stability of a pentavalent phosphorus compound (the pentachloride and pentabromide dissociate into a molecule of the halogen element and phosphorus trichoride).
Taking as types hydrogen, hydrochloric acid, water and ammonia, he postulated that all organic compounds were referable to these four forms: the hydrogen type included hydrocarbons, aldehydes and ketones; the hydrochloric acid type, the chlorides, bromides and iodides; the water type, the alcohols, ethers, monobasic acids, acid anhydrides, and the analogous sulphur compounds; and the ammonia type, the amines, acid-amides, and the analogous phosphorus and arsenic compounds.
Perkin, junr., in 1883, that ethylene and trimethylene bromides are capable of acting in such a way on sodium acetoacetic ester as to form triand tetramethylene rings.
For instance, constant differences are found between the chlorides, bromides and iodides of sodium and potassium According to H.
With ammonia and alkaline bromides and iodides double salts are formed.
The bromides and iodides resemble the chlorides.
Aurous bromide, AuBr, is a yellowish-green powder obtained by heating the tribromide to 140°; auric bromide, AuBr 3, forms reddish-black or scarlet-red leafy crystals, which dissolve in water to form a reddishbrown solution,and combines with bromides to form bromaurates corresponding to the chloraurates.
The anhydrous chlorides of nickel, cobalt, cadmium, barium, iron and lead act in the same way as catalysts at about 300° C., and the bromides of lead, cadmium, nickel and barium at about 320° C.
Sulphuric acid is now added to the liquid, and any alkaline sulphides and sulphites present are decomposed, while iodides and bromides are converted into sulphates, and hydriodic and hydrobromic acids are liberated and remain dissolved in the solution.
The iodides as a class resemble the chlorides and bromides, but are less fusible and volatile.
10 a Analogous bromine and iodine compounds are unknown, since bromides and iodides on heating with potassium bichromate and concentrated sulphuric acid give free bromine or free iodine.
They can be distinguished from the corresponding bromides and iodides by the fact that on distillation with a mixture of potassium bichromate and concentrated sulphuric acid they yield chromium oxychloride, whereas bromides and iodides by the same treatment give bromine and iodine respectively.
The waters are tasteless and inodorous, and contain calcium and magnesium bicarbonates, combinations of hydrogen and silicon, and of iodides, bromides and lithium.
The bromides closely resemble the chlorides and fluorides.
(K-k) 2 = 2T/gp the specific cohesion, we may state the general results of his experiments as follows: The bromides and iodides have a specific cohesion about half that of mercury.
Similar bromides and iodides are known.
Potassium, sodium and magnesium bromides are found in mineral waters, in river and sea-water, and occasionally in marine plants and animals.
With the other elements it unites to form bromides, often with explosive violence; phosphorus detonates in liquid bromine and inflames in the vapour; iron is occasionally used to absorb bromine vapour, potassium reacts energetically, but sodium requires to be heated to 200° C. The chief use of bromine in analytical chemistry is based upon the oxidizing action of bromine water.
It cannot be prepared with any degree of purity by the action of concentrated sulphuric acid on bromides, since secondary reactions take place, leading to the liberation of free bromine and formation of sulphur dioxide.
Hydrobromic acid reacts with metallic oxides, hydroxides and carbonates to form bromides, which can in many cases be obtained also by the direct union of the metals with bromine.
As a class, the metallic bromides are solids at ordinary temperatures, which fuse readily and volatilize on heating.
Sodium nitrate, potassium nitrate, potassium chloride, ammonium chloride, the alkaline iodides and bromides, also belong partly to this group, although most of them have also specific actions.
Alkaline bromides, in addition to their saline action, have in sufficient doses a depressing effect upon the central nervous system, and less markedly upon the heart.
The non-metallic bromides are usually liquids, which are readily decomposed by water.
Silver nitrate in the presence of nitric acid gives with bromides a pale yellow precipitate of silver bromide, AgBr, which is sparingly soluble in ammonia.
In medicine it is largely employed in the form of bromides of potassium, sodium and ammonium, as well as in combination with alkaloids and other substances.
Of the three bromides in common use the potassium salt is the most rapid and certain in its action, but may depress the heart in morbid states of that organ; in such cases the sodium salt - of which the base is inert - may be employed.
The conditions in which bromides are most frequently used are insomnia, epilepsy, whooping-cough, delirium tremens, asthma, migraine, laryngismus stridulus, the symptoms often attendant upon the climacteric in women, hysteria, neuralgia, certain nervous disorders of the heart, strychnine poisoning, nymphomania and spermatorrhoea.