Nitriles, nitro and azo compounds

These chemicals are mostly intermediates. Acrylonitrile goes into acrylic fibres and ABS plastics, adiponitrile into nylon, nitrobenzene into aniline, isocyanates into polyurethane foams, coatings and adhesives, and oximes into caprolactam and anti-skinning agents. Acetonitrile is also a leading HPLC solvent. Buyers should specify assay, water, colour, acidity and, for isocyanates, the NCO content, hydrolysable chlorine and viscosity.

Hazards are significant in this group. Isocyanates are respiratory sensitisers, many nitriles and nitro compounds are toxic, and some azo and nitro compounds are energetic and need careful storage. Isocyanates react with moisture, so deliveries are made under dry nitrogen. In the Harmonized System, nitriles fall under heading 2926, azo compounds under 2927, hydrazine and hydroxylamine derivatives under 2928 and isocyanates under 2929, while nitro aromatics are found under 2904.