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2-Nitrobenzaldehyde (2-NBA) is a multifunctional compound used in dyes, pharmaceuticals, food, and organic synthesis. Due to its distinctive yellow crystalline appearance, 2-NBA is used as an intermediate in the synthesis of indigo dyes. It is also used in the synthesis of 2-Nitrobenzyl-chitosan and nifedipine. Furthermore, 2-NBA can be used as a preservative in meat products, for the preservation of meat and food (preventing light damage), and has applications in the packaging industry.

YELLOW CRYSTALLINE POWDER OR NEEDLES

2-Nitrobenzaldehyde is a benzaldhyde with a nitro group substituted in the ortho position. 2-Nitrobenzaldehyde is used in the preparation of dyes and colorants such as Indigo carmine. 2-Nitrobenzaldeh yde gas been shown to be a useful photoremovable protecting group as well as in the preparation of more effective ones such as o-Nitrophenylethylene glycol.

2-Nitrobenzaldehyde can react with chitosan to form 2-nitrobenzyl-chitosan, which is soluble in trifluoroacetic acid and can also be electrospun into nanofiber matrices. On photolysis, the nitrobenzyl group is cleaved to form neat chitosan nanofiber matrices. The same principle has been applied for the preparation of gelatin nanofiber matrices. The condensation of o-NBA with 2-aminobenzothiazole forms o-nitrobenzylidene 2-aminobenzothiazole, a Schiff′s base that can react with metal ions to form complexes.

ChEBI: Benzaldehyde substituted at the ortho-position with a nitro group.

2-Nitrobenzaldehyde is synthesized from 2-Nitrotoluene by nitration and oxidation.
Synthesis of 2-Nitrobenzaldehyde from 2-Nitrotoluene

Synthetic Communications, 19, p. 3385, 1989 DOI: 10.1080/00397918908052745

50 g (0.24 mol) of 2-nitrophenylpyruvic acid of melting point 115° C are introduced into 500 ml of aqueous sodium carbonate until a clear solution is obtained. After the addition of 350 ml of toluene, the mixture is cooled to 0° C, and 40 g of solid potassium permanganate is then added in portions at 0°- 3° C. After one hour at 0°- 3° C, 95 ml of 50% strength sulphuric acid are added dropwise. The temperature is not allowed to rise above 30° C. The reaction mixture is filtered, and the toluene phase is separated from the filtrate. The filter residue is washed with toluene, and the combined toluene phases are extracted with 15% strength sodium carbonate solution and with water. The toluene phase is then dried with sodium sulfate and concentrated in a vacuo. The remaining residue consists of 19.7 g (54.7% of theory) of 2-nitrobenzaldehyde, which crystallizes on cooling.

Crystallise the aldehyde from toluene (2-2.5mL/g) by addition of 7mL pet ether (b 40-60o) for 1mL of solution. It can also be distilled under reduced pressures. [Beilstein 7 IV 584.]