Partly for this reason, 2-nitrobenzaldehyde is prepared by indirect routes.

The vinyl group can be oxidized in a number of different ways to yield 2-nitrobenzaldehyde.

[6][7] Alternatively, 2-nitrotoluene as formed above can be halogenated to a 2-nitrobenzyl halide followed by oxidation with DMSO and sodium bicarbonate to yield 2-nitrobenzaldehyde, which is subsequently purified with the creation of a bisulfite adduct.

In the Baeyer-Drewson indigo synthesis, 2-nitrobenzaldehyde condenses with acetone in basic aqueous solution to yield indigo in a one-pot synthesis[9][10] The method was abandoned in the early part of the 20th century, being replaced by routes from aniline.

[11] Given its two relatively reactive groups, 2-nitrobenzaldehyde is a potential starting material for other compounds.