Phosphate, Tribasic

Tribasic phosphate Stable under basic conditions Considered immobile... 

Elemental composition Ca 38.76%, P 19.97%, 0 41.26%. Calcium may he analyzed by AA, and ICP, or x-ray methods (see Calcium). The orthophosphate anion may be analyzed by colorimetry (see Phosphorus). For colorimetric analysis the insoluble tribasic phosphate must be brought into aqueous phase hy dissolving in dilute sulfuric acid. 

All basic magnesium phosphates find apphcations in plastics as stabilizers. Other than this, monobasic salt is used in fireproofing wood. The dibasic phosphate is a food additive and also a laxative. The tribasic phosphate is an antacid and a nutritional food supplement. The compound also is an adsorbent and a pohshing agent in dental work. 

The tetrahydrate of the tribasic phosphate, Mg3(P04)2 4H2O is a bulky and soft white powdery material monochnic crystals density 1.64 g/cm at 15°C slightly soluble in water (0.2 g/L at 20°C) soluble in acids. The naturally occurring octahydrate, bobierite, is a white crystalline solid, containing monoclinic plates refractive index 1.510 density 2.195 g/cm at 15°C loses three molecules of water of crystallization at 150°C loses all water at 400°C insoluble in water soluble in dilute mineral acids. 

The basic phosphates that occur naturally may be mined from their respective minerals. They may be prepared by reactions of phosphoric acid with magnesium oxide and hydroxide followed by crystallization. Monobasic and dibasic magnesium phosphate are prepared by the action of phosphoric acid on magnesium hydroxide and magnesium oxide, respectively. The tribasic phosphate is made by treating magnesium oxide with phosphoric acid at high temperature. 

Under a flow of argon, P2S5 (0.75 g, 1.68 mmol) was mixed with Na2C03 (0.18 g, 1.7 mmol) in dry THF (100 mL). The mixture was stirred for 1 h at 25 °C and then cooled to 0°C. To the clear soln was added Boc-Ala-2-aminoanilide (0.5 g, 1.79 mmol), and the reaction was kept at 0 °C overnight. An aqueous soln of sodium tribasic phosphate was then added (12%, 7mL), followed by EtOAc (20 mL) and heptane (20 mL). The organic layer was separated and washed with brine (2 x 30 mL). The solvent was then removed and the residue was purified by chromatography (silica gel, EtOAc/hexane 1 2) to give pure Boc-Ala-2-aminothioanilide as a pale yellow solid yield 0.28 g (53%) mp 124-126 °C. 

Aqueous samples extracted with chloroform chloroform extract further extracted with 1 M HjSO, the acid extract buffered with 0.4 M sodium tribasic phosphate and then pH adjusted between 6 and 7 using NaOH the neutralized extract then treated with chloroform organic layer separated and concentrated benzidine analyzed by HPLC using an electrochemical detector (i.e., glassy carbon electrode). 

Orthophosphates.—Solubility.—The tribasic phosphates of the alkali metals and ammonia are soluble, while those of the alkaline earth metals and the common metals are insoluble. They are usually prepared by double decomposition between disodium hydrogen phosphate and a salt of the required metal, thus... 

When two mols of sulphuric acid are added to one of the tribasic phosphate more than 96 per cent, of the phosphate is rendered freely soluble in water, superphosphate being formed as follows —... 

In practice it is arranged that a little of the tribasic phosphate is left undecomposed, and this then reacts according to the equation... 

Properties Pink powder, contains some tribasic phosphate. Soluble in acids slightly soluble in water. 

Pink form, usually contains some tribasic phosphate. Very slightly so] in water sol in dil acids. Gray form, sol only in hot conod HC1. 

When a pyrophosphate is melted with excess of hase, it is converted into a tribasic phosphate. Thus, if pyrophosphate of soda be fused with an additional equivalent of soda, the tribasic salt, P, Oj, 3 NaO is formed, which no longer contains pyro-phosphoric acid. 

Manufacturing aspects of belite doped with barium sulfate (BaSO ), calcium tribasic phosphate [Caj(PO )30H],... 

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