Strontium fluorinated compounds

The exceptional character o fluorine.—Fluorine has a little more individuality, so to speak, than the other three members of the family (1) There are no compounds of oxygen and fluorine (2) Chlorine, bromine, and iodine or the haloid acids show no signs of the remarkable effect of hydrofluoric acid and of fluorine on silicon (3) The solubilities of the sulphates, nitrates, and chlorides of barium, strontium, calcium, and magnesium decrease with increasing at. wt. of the metal, while the solubilities of the hydroxides increase the solubilities of the iodides, bromides, and chlorides... 

B. About 20 elements are called minerals. They also play a role in human nutrition. The minerals known to be essential for good health are calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium, iron, manganese, copper, iodine, cobalt, fluorine, and zinc. Traces of sihcon, boron, arsenic, strontium, aluminum, bromine, molybdenum, selenium, and nickel may also be required. These elements are eaten in the form of their compounds, but it does not matter much which compounds. 

Bollard and Butler (1966) in their discussion of functional elements include several others in addition to the above four. They state that fluorine, iodine, and selenium fall in this class for in some plant species they are metabolized, forming definite organic compounds. Bromine, rubidium, and strontium are also placed in this class because they exert a sparing effect on the utilization of chloride, potassium and calcium. Cobalt may perform that same function. They state further that our knowledge of the beneficial effects produced by aluminum, beryllium, and barium are not as yet adequate to justify including these in the group of functional elements. Further research will probably add other elements to this group. 

Perchlorates are powerful oxidizing substances. These compounds explode when mixed with combustible, organic, or other easily oxidizable compounds and subjected to heat or friction. Perchlorates explode violently at ambient temperatures when mixed with mineral acids, finely divided metals, phosphorus, trimethylphosphite, ammonia, or ethylenediamine. Explosions may occur when perchlorates are mixed with sulfur, or hydride of calcium, strontium, or barium and are subjected to impact or ground in a mortar. Perchlorates react with fluorine to form fluorine perchlorate, an unstable gas that explodes spontaneously. Heating perchlorates to about 200°C (392°F) with charcoal or hydrocarbons can produce violent explosions. Metal perchlorates from complexes with many organic solvents, which include benzene, toluene, xylenes, aniline, diozane, pyridine, and acetonitrile. These complexes are unstable and explode when dry. Many metal perchlorates explode spontaneously when recrystaUized from ethanol. Saturated solution of lead perchlorate in mathanol is shock sensitive. 

Aly and Huang discussed the removal of several cations such as barium, iron, vanadium, and selenium, and several chlorine, fluorine, and cyanide compounds. More recently, activated carbons have also been used for the adsorptive removal of sulfides, nitrates, chlorides, chlorites, and chlorates, cyanides, " boric acid, borax, and borates, as well as certain metals such as lithium, cerium, iron, strontium, and dysposium from the aqueous phase. 

A variation of calcium phosphate is the major component of bones and teeth in all vertebrates including humans. These calcium phosphates are usually referred to collectively as biological apatites, which are nonstoichiometric compounds based on pure apatites, Ca5(P04)3X, where X can be fluorine (F), chlorine (Cl), or hydroxyl (OH). (These are called fluoro-, chloro-, and hydroxyapatite, respectively.) In biological apatites the calcium cations can be replaced with varying amounts of strontium, magnesium, sodium, and potassium ions, and the phosphate anions can be replaced with hydrogen phosphates and carbonates. 

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