Aurin (p-Rosolic Acid)

Aurin, also known as p-Rosolic Acid, is a triphenylmethane dye with notable pH-sensitive color changes. Here's a more detailed description:

Key Characteristics and Properties:

• Chemical Structure:
  • It's a triphenylmethane dye, meaning its structure is based on a central carbon atom bonded to three phenyl rings.
  • Its chemical formula varies slightly depending on the degree of hydration, but the core structure is C₁₉H₁₄O₃.
• pH Indicator:
  • Aurin is primarily known for its use as a pH indicator.
  • It exhibits a distinct color change depending on the acidity or alkalinity of the solution:
    • Yellow in acidic solutions.
    • Red in alkaline solutions.
  • The color transition occurs within a specific pH range, making it useful for determining the pH of various substances.
• Coloration:
  • It is a bright colored solid.
• Solubility:
  • It's generally soluble in alcohols and alkaline solutions, but less so in water.

Applications:

• Analytical Chemistry:
  • It's used in various analytical techniques, primarily as a pH indicator in titrations and other pH-related measurements.
• Microscopy:
  • It has been used in some microscopy applications for staining certain biological samples.
• Research:
  • It is used in research regarding pH related studies.

Important Considerations:

• Sensitivity:
  • Aurin's color change is sensitive to pH variations, making it a valuable tool for detecting changes in acidity or alkalinity.
• Limitations:
  • Like other pH indicators, aurin has limitations in its pH range and may not be suitable for all applications.

In essence, aurin's pH-dependent color changes make it a useful tool in analytical chemistry and other fields where pH measurement is essential.