Aniline. Molecular model of the aromatic amine aniline (C6.H5.N.H2), precursor to many industrial chemicals such as polyurethane. It is also known as phenylamine or aminobenzene. It is a blue dye that was first isolated from indigo in the 1820s. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white) and nitrogen (blue).