6-Aminonaphthalene-2-sulfonyl fluoride (ANF) is a fluorinated sulfonamide derivative widely utilized as a reactive intermediate in organic synthesis and bioconjugation chemistry. Its key structural features include a naphthalene backbone with an electron-rich amino group at the 6-position and a highly electrophilic sulfonyl fluoride moiety at the 2-position. The sulfonyl fluoride group exhibits exceptional reactivity toward nucleophiles, particularly serine residues in proteins, enabling site-specific labeling and proteomic applications. ANF's naphthalene core enhances fluorescence properties, facilitating detection in analytical workflows. Compared to similar reagents, it demonstrates improved hydrolytic stability while maintaining selective reactivity, making it valuable for designing covalent inhibitors, activity-based probes, and functionalized materials under mild aqueous conditions. The compound's dual functionality (amine and sulfonyl fluoride) further allows sequential derivatization strategies.