Chlorine oxide

Oxides or oxides are the compounds of various elements with oxygen. Almost all elements form such compounds. Chlorine, like other halogens, is characterized in such compounds by a positive oxidation state. All chlorine oxides are extremely unstable substances, which is characteristic of oxides of all halogens. Four substances are known, in which molecules contain chlorine and oxygen.

1. The gaseous compound from yellow to reddish with a characteristic odor (reminiscent of the smell of Cl2 gas) is chlorine oxide (I). The formula is chemical Cl2O. Melting point minus 116 ° C, boiling point plus 2 ° C. Under normal conditions, its density is 3.22 kg / m³.
2. Yellow or yellow-orange gas with a characteristic odor - chlorine oxide (IV). Formula Chemical ClO2. Melting point minus 59 ° C, boiling point plus 11 ° C.
3. Red-brown liquid is chlorine (VI) oxide. The formula is chemical Cl2O6. Melting point plus 3.5 ° C, boiling point plus 203 ° C.
4. Colorless oily liquid - chlorine oxide (VII). Formula Chemical Cl2O7. The melting point is minus 91.5 ° C, the boiling point is plus 80 ° C.

Chlorine oxide with an oxidation state of +1 is anhydride of a weak monoacid hypochlorous acid (HClO). It is obtained by the Peluse method by the interaction of mercury oxide with gaseous chlorine by one of the reaction equations: 2Cl2 + 2HgO → Cl2O + Hg2OCl2 or 2Cl2 + HgO → Cl2O + HgCl2. The conditions of these reactions are different. Chlorine oxide (I) is condensed at minus 60 ° C, because at higher temperatures it decomposes, explodes, and is explosive in concentrated form. An aqueous solution of Cl2O is obtained by chlorinating in water alkali or alkaline metal carbonates. Oxide is highly soluble in water, and hypochlorous acid is formed: Cl2O + H2O ↔ 2HClO. In addition, it also dissolves in carbon tetrachloride.

Chlorine oxide with an oxidation state of +4 is otherwise called dioxide. This substance is soluble in water, sulfuric and acetic acids, acetonitrile, carbon tetrachloride, as well as in other organic solvents, with increasing polarity of which its solubility increases. Under laboratory conditions, it is obtained by reacting potassium chlorate with oxalic acid: 2KClO3 + H2C2O4 → K2CO3 + 2ClO2 + CO2 + H2O. Since chlorine (IV) oxide is an explosive substance, it can not be stored in solution. For these purposes, silica gel is used, on the surface of which, in the adsorbed form of ClO2 can be stored for a long time, it is simultaneously possible to get rid of contaminating chlorine impurities, since it is not absorbed by silica gel. In industrial conditions, ClO2 is obtained by reduction with sulfur dioxide, in the presence of sulfuric acid, sodium chlorate: 2NaClO3 + SO2 + H2SO4 → 2NaHSO4 + 2ClO2. It is used as a bleach, for example, paper or cellulose, etc., as well as for sterilization and disinfection of various materials.

Chlorine oxide with a degree of oxidation of +6, during melting decomposes according to the reaction equation: Cl2O6 → 2ClO3. Chlorine (VI) oxide is obtained by oxidizing with ozone dioxide: 2O3 + 2ClO2 → 2O2 + Cl2O6. This oxide is able to react with alkali solutions and with water. Disproportionation reactions occur. For example, when interacting with potassium hydroxide: 2KOH + Cl2O6 → KClO3 + KClO4 + H2O, chlorate and potassium perchlorate are obtained as a result.

The higher chlorine oxide is also called chlorine anhydride or dichloroheptaoxide is a strong oxidizer. It is capable of blowing up or heating up. However, this substance is more stable than oxides with a degree of oxidation of +1 and +4. Its decomposition to chlorine and oxygen is accelerated because of the presence of lower oxides and with an increase in temperature from 60 to 70 ° C. Chlorine oxide (VII) is able to dissolve slowly in cold water, resulting in the formation of perchloric acid: H2O + Cl2O7 → 2HClO4. The dichloroheptoxide is prepared by gently heating the perchloric acid with phosphoric anhydride: P4O10 + 2HClO4 → Cl2O7 + H2P4O11. Also, Cl2O7 can be obtained using oleum instead of phosphorus anhydride.

The section of inorganic chemistry that studies halogen oxides, including chlorine oxides, has been developing actively in recent years, as these compounds are energy-intensive. They are able to give energy instantly to the combustion chambers of jet engines , and in chemical sources of current the rate of its recoil can be regulated. Another reason for interest is the possibility of synthesizing new groups of inorganic compounds, for example, chlorine oxide (VII) is the ancestor of perchlorates.