4-Chloro-2-nitrobenzenediazonium Chloride is reduced in the presence of hypophosphorous acid and carbon powder resulting in functionalized carbon powder with chloronitrophenyl groups attached on carbon particle surface; Also, it is an intermediate used in the synthesis of 2,4-Di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol-d20 (D428017), which is an isotope labelled form of 2,4-Di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol (D428015), which is a UV absorber. Molecular Formula: C6H3Cl2N3O2 Molecular Weight: 220.01