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2 Nitrobenzaldehyde

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Molar mass  151.12 g/mol
Formula  C7H5NO3
2-Nitrobenzaldehyde 2Nitrobenzaldehyde Wikipedia
Appearance  Pale yellow crystalline powder

2-Nitrobenzaldehyde is an organic aromatic compound containing a nitro group ortho to formyl. 2-Nitrobenzaldehyde once was produced as an intermediate in the synthesis of the popular dye Indigo.

Contents

2-Nitrobenzaldehyde 2Nitrobenzaldehyde55289613CNMR

Synthesis

2-Nitrobenzaldehyde wwwsigmaaldrichcomcontentdamsigmaaldrichstr

The main routes to nitrobenzaldehyde begin with the nitration of styrene and cinnamic acid followed by the conversions of the resulting 2-nitrostyrene and 2-nitrocinnamic acids. Cinnamaldehyde can also be nitrated, e.g., in a solution of acetic anhydride in acetic acid, in high-yield to 2-nitrocinnamaldehyde. This compound is then oxidized to 2-nitrocinnamic acid, which is decarboxylated to the 2-nitrostyrene. The vinyl group can be oxidized in a number of different ways to yield 2-nitrobenzaldehyde.

2-Nitrobenzaldehyde 4Bromo2nitrobenzaldehyde 97 SigmaAldrich

In one synthetic process, toluene is mono-nitrated at cold temperatures to 2-nitrotoluene, with about 58% being converted to the ortho- isomer, the remaining forming meta- and para- isomers. The 2-nitrotoluene can then be oxidized to yield 2-nitrobenzaldehyde.

2-Nitrobenzaldehyde 2Nitrobenzaldehyde C7H5NO3 ChemSpider

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.

2-Nitrobenzaldehyde 4Dimethylamino2nitrobenzaldehyde 97 SigmaAldrich

The nitration of benzaldehyde produces mostly 3-nitrobenzaldehyde, with yields being about 19% for the ortho-, 72% for the meta- and 9% for the para isomer. For this reason, the nitration of benzaldehyde to yield 2-nitrobenzaldehyde is not cost-effective.

Uses

2-Nitrobenzaldehyde 4Bromo2nitrobenzaldehyde CAS Number 908334043

2-Nitrobenzaldehyde is an intermediate in an early route to indigo, a water-insoluble dye commonly used to dye jeans and other fabrics. In the Baeyer-Drewson indigo synthesis, 2-nitrobenzaldehyde condenses with acetone in basic aqueous solution to yield indigo in a one-pot synthesis. The method was abandoned in the early part of the 20th century, being replaced by routes from aniline.

Given its two relatively reactive groups, 2-nitrobenzaldehyde is a potential starting material for other compounds. Substituted 2-nitrobenzaldehydes can also be used to yield other important compounds based on indigo, such as indigo carmine.

2-Nitrobenzaldehyde has been shown to be a useful photoremovable protecting group for various funcions.

References

2-Nitrobenzaldehyde Wikipedia


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