Murexide
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| General | ||||||||||||||||
| Surname | Murexide | |||||||||||||||
| other names |
Purple ammonium salt |
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| Molecular formula | C 8 H 8 N 6 O 6 | |||||||||||||||
| Brief description |
dark red-brown solid |
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| properties | ||||||||||||||||
| Molar mass | 284.19 g · mol -1 | |||||||||||||||
| Physical state |
firmly |
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| Melting point |
> 250 ° C (decomposition) |
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| solubility |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||||||||
Murexide is the name for the acidic ammonium salt of purpuric acid (C 8 H 5 N 5 O 6 ), which does not exist in the free state . It is an indicator for the titration of metals . Murexide is also the end product of the murexide reaction , a chemical detection reaction for uric acid , xanthine and related substances.
history
The fact that murexide is the acidic ammonium salt of purple acid was described by Friedrich Konrad Beilstein in his dissertation " About Murexide ", which he wrote in 1858 with Friedrich Wöhler in Göttingen ; at Beilstein it is called " acidic purple acid ammonia ".
properties
Murexide forms a red-brown powder that is insoluble in ether and alcohol and dissolves slightly (1 g / l) in water at 20 ° C. It dissolves better in hot water. The color changes from red to blue when alkali is added. Murexide is used in the pH range from 9 to 12 as a metal indicator in the complexometric titration of nickel , cobalt , copper and calcium (color change from yellow or red to blue-violet) and for the cerimetric determination of fluorine .
