Sodium trimetaphosphimates

Sodium trihydroxothioferrate(II), Na3FeS(OH)s, formation of, in preparation of potassium dithioferrate(III), 6 170 Sodium trimetaphosphimates, 6 80 Na3(P02NH)3, 1-hydrate, 6 99 4-hydrate, purification and acid hydrolysis of, for preparation of pentasodium diimidotri-phosphate, 6 105 Na3(P02NH)3-NaOH-7H20, 6 80 Sodium triphosphate (tripolyphosphate), 3 101 6-hydrate, 3 103... 

P3N203H4lprismatic crystals, neutral to litmus, while penta-sodium diimidotriphosphate has an alkaline reaction. The trisilver salt forms monoclinic crystals. Warming the pentasilver salt with ammonium nitrate destroys the yellow colour—yellow silver phosphate is not whitened by this treatment, while silver trimetaphosphimate becomes orange-yellow. The empirical composition of the acid corresponds with either ... 

H. N. Stokes prepared salts of triimidotetraphosphoric add, HN PO(OH).NH. PO(OH)2 2, by the hydrolysis of salts of pentametaphosphimic acid—e.g. a hot acetic acid soln. of sodium pentametaphosphate furnishes sodium triimidotetra-phosphate, NH PO(OH).NH.PO(ONa)2 2 and the addition of silver nitrate to the soln. furnishes the silver triimidotetraphosphate, HN PO(OH).NH.PO(OAg)2 2. The acid is so unstable that it cannot be made by heating tetrametaphosphimate as might have been anticipated by the formation of diimidotriphosphoric acid by the action of heat on trimetaphosphimic acid. 

While the hydrolysis of triphosphonitrilic chloride with sodium acetate furnishes trimetaphosphimic acid and the hydrolysis of tetraphosphonitrilic chloride with water furnishes tetrametaphosphimic acid, the hydrolysis of pentaphosphonitrilic chloride, P5N5C1i0, with sodium hydroxide in ethereal soln. furnishes sodium pentametaphosphimic acid, PsNsHloO10, or rather the alkali pentameta-phosphimate—sufficient alkali must be present to maintain the alkalinity of the soln. The sodium salts are amorphous, and are precipitated in a gelatinous form by the addition of alcohol to the alkaline soln., or to the soln. neutralized with acetic... 

Pentametaphosphimic Acid and Hexametaphosphimic Acid were similarly obtained by hydrolysis in ethereal solution of the corresponding nitrilo-chlorides. Like the lower polymers they gave crystalline sodium salts containing water of crystallisation, and anhydrous penta- and hexa-silver salts by the use of ammoniacal silver nitrate. The free acids can be regenerated by the action of H2S on the silver salts. The acids are more stable towards hydrolysing agents than is trimetaphosphimic acid. 

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