N 1705 (OTTO) 2-Nitro benzaldehyde, 99% Cas 552-89-6 - used as a starting material in synthetic chemistry. It is used as an intermediate during the synthesis of Indigo dye. It is involved in the preparation of colorants such as Indigo carmine. Further, it serves as a useful photoremovable protecting group as well as utilized in the preparation of o-nitrophenylethylene glycol.