Basic salts are a fairly large group of compounds. This group includes borates, halides, nitrites, sulfites. The group "basic salts" includes carbonates, nitrates, sulfates.
The borate category includes several types of compounds. In particular, metabolic (HBO2), orthoboric (HB3O3), and also polyboric acids that are not isolated to the free state are classified as borates. In accordance with the number of boron atoms, these basic salts are divided into hexa-, tetra-, di-, monoborates, etc. Borates can be named for the acids that form them and the number of moles of B2O3, which is 1 mole of the base oxide.
The interaction of metals with salts (ammonium, alkaline and others) with an oxidation state of +1 involves the formation, as a rule, of anhydrous and hydrated metabolites of the MBO2 type, MB5O8 pentaborates, M2B4O7 tetraborates, and others.
Borates are colorless crystals or amorphous substances. Usually they differ in a low-symmetric structure - rhombic or monoclinic.
Anhydrous borates have a melting point in the range of 500 - 2000 degrees. Metaborites of alkali metals, as well as meta- and orthoborates of alkaline-earth compounds, are among the most melting ones. Most substances easily form glass upon cooling the melts.
The loss of crystallization water in hydrated monoborates occurs at a temperature of about one hundred and eighty, and in polyborates - three hundred to five hundred degrees. Complete dehydration leads to the formation of amorphous substances, which undergo crystallization at five hundred to eight hundred degrees. As a result of this “rearrangement”, partial decomposition of compounds and the release of B2O3 occur.
Alkali metal borates are characterized by their ability to dissolve in water. This is especially true for penta- and metabolites. Most of these basic salts are readily decomposed by acids. In some cases, decomposition also occurs under the influence of SO2 and CO2.
Borates of heavy and alkaline earth metals are able to interact with alkaline, carbonate and bicarbonate solutions. Anhydrous compounds are more chemical resistant than hydrated ones. With a number of alcohols, with glycerol, in particular, borates form water-soluble complexes. Under the influence of strong oxidizing agents, 22, in particular, or during electrochemical oxidation, conversion to pexoborates occurs.
About one hundred borates are known in nature. They are mainly salts of Mg, Na, Fe, Ca. It should be said that these elements are used quite widely. In particular, the chlorides of these elements are a type of substance such as “technical salt”, which, in turn, is used in various industries.
Anhydrous borates are obtained by dehydration. Sintering or alloying of B2O3 with carbonates or metal oxides is also used. Single crystals are grown in molten oxides, for example Bi2O3. Hydrated borates are produced by the reactions of the mutual conversion of sparingly soluble compounds with aqueous solutions of alkali metal borates, by means of H3BO3 neutrolization with metal hydroxides, oxides or carbonates.
Borates are used in the preparation of other boron compounds. In particular, as components of the charge in the manufacture of glasses, enamels, glazes, ceramics. Compounds are used in the manufacture of impregnations and fireproof coatings. Borates are used for refining as fluxes, in brazing and welding of metals. They are used as fillers and pigments for paints and varnishes, mordants for dyeing, as well as corrosion inhibitors (retardants), electrolyte components, phosphors and others. The most commonly used are borates of calcium and borax.