Used primarily as a reference standard in pharmaceutical quality control and analytical testing during the synthesis and purification of ibrutinib, a Bruton's tyrosine kinase (BTK) inhibitor. It helps in identifying and quantifying impurities in ibrutinib drug substances and formulations, ensuring product purity, safety, and compliance with regulatory requirements. Commonly employed in high-performance liquid chromatography (HPLC) and mass spectrometry (MS) methods for impurity profiling.