Used as a pH indicator in acid-base titrations, particularly in non-aqueous systems. It changes color from yellow to red around pH 3.0 to 4.4, making it suitable for detecting the endpoint in titrations involving weak bases or in solvents where traditional indicators are ineffective. Commonly applied in the analysis of organic compounds and in industrial quality control for acid number determination. Also utilized in educational labs to demonstrate pH changes in non-aqueous environments.