3-Nitro-o-phenylenediamine (NOPD) is an organic compound used in the production of dyes and pigments. It is also known as 3-nitro-1,2-phenylenediamine or 4-nitro-o-phenylenediamine. NOPD is a yellow crystalline solid with the chemical formula C6H7N3O2. It is commonly used as an intermediate in the synthesis of azo dyes, which are widely used in textiles, printing, and coloring applications. Additionally, NOPD can be employed as a colorant in hair dyes and cosmetics due to its ability to impart a yellow to orange color.