Murexide
[CAS# 3051-09-0]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Inorganic ammonium salt
• Name: Murexide
• Synonyms: Ammonium purpurate; Ammonium 5-(2,4,6-trioxoperhydropyrimidin-5-ylideneamino)barbiturate
• Molecular Formula: C₈H₈N₆O₆
• Molecular Weight: 284.18
• CAS Registry Number: 3051-09-0
• EC Number: 221-266-6
• SMILES: c1(c([nH]c(=O)[nH]c1=O)[O-])N=C2C(=O)NC(=O)NC2=O.[NH4+]

Properties

• Melting point: >300 ºC
• Water solubility: Slightly soluble 1 g/L

Safety Data

• Safety Description: S22;S24/25

Discovory and Applicatios

Murexuric acid is a complex organic compound with the molecular formula C₈H₈N₆O₆. It is a well-known dye and analytical reagent known for its bright color change and role in complexometric titration. Murexuric acid was discovered in the 19th century while studying purine derivatives. The compound was first synthesized by Justus von Liebig and Friedrich Wöhler in the 1850s while studying uric acid. They found that heating uric acid with concentrated nitric acid and ammonia produced a purple-red substance, which they identified as ammonium murexuric acid. This discovery was significant at the time because it helped understand the chemical properties of purines and their derivatives.

The synthesis of murexuric acid generally involves the oxidation of uric acid followed by reaction with ammonia. The process can be summarized as follows: uric acid is oxidized using concentrated nitric acid to form streptozotocin, which is then reacted with ammonia to form murexuric acid. The compound produced by this process crystallizes as reddish-purple needles and exhibits a bright color change from red under acidic conditions to purple under alkaline conditions.

Murexuric acid is widely used as an indicator in complexometric titrations, particularly for the determination of calcium and other metal ions. Its ability to form complexes with metal ions and exhibit a distinct color change makes it a valuable tool for quantitative analysis in a variety of fields, including environmental monitoring, clinical chemistry, and water hardness testing.

The bright red-purple color of murexuric acid has historically been a popular dye for textiles and inks. Although the use of murexuric acid in the dye industry has declined with the advent of synthetic dyes, it remains of interest in specialized applications where specific color properties are required.

In educational settings, murexuric acid is frequently used in experiments to demonstrate the principles of complex formation and colorimetric analysis. Its clear and dramatic color change provides a visual and practical approach to teaching basic concepts in chemistry.

Murexuric acid has played a vital role in the historical development of organic chemistry. The study of purine derivatives, including murexuric acid, laid the foundation for major advances in biochemistry and medicine. The methods developed to synthesize and analyze it have influenced a variety of chemical processes and techniques used today.

Recent studies have explored the potential biomedical applications of murexuric acid and its derivatives. Its complexing properties and interactions with metal ions are being studied for use in medical diagnostics and therapeutics, particularly in areas related to metal ion homeostasis and detoxification.

References

1963. Determination of ionized calcium in serum with murexide. Analytical Biochemistry, 6(6).
DOI: 10.1016/0003-2697(63)90140-4

2007. A Simple Flow-injection Spectrofluorimetric Method for the Determination of Mercury. Journal of Fluorescence, 17(3).
DOI: 10.1007/s10895-007-0182-4

2012. An indicator-displacement assay for naked-eye detection and quantification of histidine in human urine. The Analyst, 137(9).
DOI: 10.1039/c2an35126a