Blue colour of the jeans is due to aniline dyeing agent. Aniline is an organic base a toxic aromatic amine, is a widely used industrial chemical, particularly in the manufacture of dyes, Plastics, rubber, resins, varnishes, perfumes, pigments, polyurethane foam, photographic developers and pesticides.
Aniline is a musty, fishy-smelling yellowish to brownish, greasy liquid. -6°C melting point; 184°C boiling temperature; 158°F flash point Water-insoluble and somewhat denser than water. Vapors are more dense than air. Because aniline is an aromatic molecule that combines readily with other aromatic compounds, a low aniline point suggests a low diesel index. A high aniline point suggests a highly paraffinic gasoline with a high Diesel index and excellent ignition quality.
Aniline is in the form of a yellowish and somewhat brownish oily liquid having a musty and a fishy odour. It smells like the odour of a rotten fish. It is a kind of chemical substance which is a flammable liquid and has an unpleasant odour. The compound is soluble in water. It can also be colourless to light brown. It has a chemical formula of C6H5NH2 or C6H7N and since it has 6 carbon atoms, 1 nitrogen atom and 7 hydrogen atoms in its chemical formula, it is classified under organic compounds.