The normal ortho-phosphate, Pb3(P04)2, is a white precipitate obtained by adding sodium phosphate to lead acetate; the acid phosphate, PbHPO 4, is produced by precipitating a boiling solution of lead nitrate with phosphoric acid; the pyrophosphate and meta-phosphate are similar white precipitates.
Other precipitants of phosphoric acid or its salts in solution are: ammonium molybdate in nitric acid, which gives on heating a canary-yellow precipitate of ammonium phosphomolybdate, 12[M00 3] (NH 4) 3 PO 4, insoluble in acids but readily soluble in ammonia; magnesium chloride, ammonium chloride and ammonia, which give on standing in a warm place a white crystalline precipitate of magnesium ammonium phosphate, Mg(NH 4)PO 4.6H 2 0, which is soluble in acids but highly insoluble in ammonia solutions, and on heating to redness gives magnesium pyrophosphate, Mg 2 P 2 0 7; uranic nitrate and ferric chloride, which give a yellowish-white precipitate, soluble in hydrochloric acid and ammonia, but insoluble in acetic acid; mercurous nitrate which gives a white precipitate, soluble in nitric acid, and bismuth nitrate which gives a white precipitate, insoluble in nitric acid.
Crystals may be obtained by heating di-calcium pyrophosphate, Ca2P207, with water under pressure.
When heated to 100° C., it loses five molecules of water of crystallization, and at a higher temperature loses the remainder of the water and also ammonia, leaving a residue of magnesium pyrophosphate, Mg 2 P 2 0 7.
The same reaction is made use of in the quantitative determination of magnesium, the white precipitate of magnesium ammonium phosphate being converted by ignition into magnesium pyrophosphate and weighed as such.
On heating they yield phosphine and leave a residue of pyrophosphate, or a mixture of metaand pyrophosphates, with a little phosphorus.
The metallic phosphites are stable both dry and in solution; when strongly heated they evolve hydrogen and yield a pyrophosphate, or, especially with the heavy metals, they give hydrogen and a mixture of phosphide and pyrophosphate.
Also, the crystals can cause occasional attacks of very painful swelling (pseudogout, or acute pyrophosphate arthritis ).
Many, but not all, people with osteoarthritis have calcium pyrophosphate crystals in their osteoarthritic joint cartilage.
A hypothetical, but typical, example involving pyrophosphate: enzyme 1: A + ATP « B + AMP + PP i.. .
This involves the prosthetic group thiamine pyrophosphate, or TPP.
pyrophosphate arthropathy Unlike gout, there is no specific therapy.
pyrophosphate deposition disease.
pyrophosphate arthritis ' .
pyrophosphate crystals in their osteoarthritic joint cartilage.
The crystal which usually causes this is calcium pyrophosphate.
thiamine pyrophosphate, or TPP.
They give a characteristic pale red precipitate with sodium pyrophosphate, soluble in an excess of the precipitant; they also form precipitates on the addition of platinic chloride and potassium ferrocyanide.
When heated to 100Ã‚° C., it loses five molecules of water of crystallization, and at a higher temperature loses the remainder of the water and also ammonia, leaving a residue of magnesium pyrophosphate, Mg 2 P 2 0 7.
A hypothetical, but typical, example involving pyrophosphate: enzyme 1: A + ATP « B + AMP + PP i...
Chronic pyrophosphate arthropathy Unlike gout, there is no specific therapy.
Jones AC, Chuck AJ, Arie EA, Green DJ, Doherty M. Diseases associated with calcium pyrophosphate deposition disease.
Osteoarthritis with crystals is sometimes called ' chronic pyrophosphate arthritis '.
But rather than being composed of uric acid, pseudogout crystals are made of calcium pyrophosphate dihydrate.
In such cases, Thiamine pyrophosphate acts as a co-factor.
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