Used in hair dye formulations as a coupling agent to produce stable, long-lasting color. Enhances shade intensity and improves color fastness by reacting with primary intermediates in oxidative dyes. Also helps achieve natural-looking hair tones, especially in medium to dark shades. Its hydrophilic nature aids in even distribution throughout the hair shaft, ensuring uniform color development. Commonly found in permanent and semi-permanent hair color products due to its effectiveness at low concentrations.