Peroxides

PEROXIDES, derivatives of hydrogen peroxide H₂O₂, with a distinction made between i n o r g a n i c P., in which the hydrogen in H₂O₂ is replaced by metals (Na₂O₂, BaO₂), and o r g a n i c P., in which hydrogen is replaced by organic radicals, for example (C₂H₅)₂O₂, (C₂H₃O)₂O₂. Peroxides are characterized by the fact that they contain 2 oxygen atoms bonded together by a chemical bond. Peroxides are characterized by: 1) the release of H₂O₂ upon the action of dilute hydrochloric or sulfuric acid, e.g., Na₂O₂ + 2HCl = 2NaCl + H₂O₂; 2) their production at ordinary temperature by a double decomposition reaction using H₂O₂: BaO + O₂ = BaO₂ + H₂O. Oxygen compounds that do not meet these criteria, such as MnO₂ or PbO₂, are not true peroxides, although this name has incorrectly persisted for them. Among inorganic peroxides, sodium peroxide, Na₂O₂, is obtained in industry by the action of dry air on sodium at 300-400°. Na₂O₂ is yellowish in color, melts at a bright red heat, does not lose oxygen upon ignition, and is a strong oxidizing agent. It is rarely used in therapy due to its strong caustic properties. In a mixture with organic substances (sawdust, cotton), Na₂O₂ produces a powerful explosion. Due to the activity of its oxygen, sodium peroxide serves for processing into other peroxide salts and peroxides and is used in large quantities for bleaching, disinfection, chemical analysis, oxygen production, etc. Soaps containing free oxygen and dissolving fat are prepared from sodium peroxide. Barium peroxide, BaO₂, is formed by heating barium oxide, BaO, in air; upon further heating above 400°, barium peroxide releases oxygen and reverts to the oxide. In recent years, world production of barium peroxide has reached 10,000 tons per year, which is explained by the low cost of obtaining barium oxide from natural baryte minerals. Barium peroxide is used to obtain H₂O₂, in aluminothermy, for luminous compositions, and for laboratory purposes. Perboric acid, HBO₃, is known only in the form of salts, perborates. Sodium perborate, NaBO₃ · 4H₂O, is obtained by the electrolysis of sodium borate or from sodium peroxide and boric acid. A stable and safe salt, easily soluble in water, it is the best substitute for H₂O₂. Its main application is in detergents, bleaching agents, cosmetics, hygiene, and also for therapeutic baths, since 1 kg of perborate releases about 70 liters of oxygen and has no harmful side effects. Calcium, magnesium, and zinc perborates are used in dermatology. Organic peroxides, ROOR, are unstable, often explosive compounds that can be obtained by the action of neutral sulfuric acid esters on H₂O₂, e.g., H—O—OH + CH₃ · O · SO₂ · O · CH₃ = CH₃O—OH + HO · SO₂ · O · CH₃; they play a major role in the oxidation reactions of organic substances by atmospheric oxygen (e.g., as an intermediate product in the oxidation of an aldehyde to an acid). Benzoyl peroxide (C₆H₅CO)₂O₂ is used for bleaching oils and as an antiseptic agent. Benzoyl hydroperoxide, C₆H₅ · CO₃ · O₂H, is used as an energetic oxidizing agent in organic synthesis. Organic peroxides also include ozonides, for example ethylene ozonide CH₂—CH₂|      |&br>O—O—O, obtained by the direct action of ozone. A. Balandin.