2-Nitrobenzaldehyde
Chemical compound
From Wikipedia, the free encyclopedia
2-Nitrobenzaldehyde is an organic compound with the formula O2NC6H4CHO. It is one of three isomers of nitrobenzaldehyde. It contains a nitro group adjacent to the formyl group.[2]
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| Names | |||
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| Preferred IUPAC name
2-Nitrobenzaldehyde | |||
| Other names
Nitrobenzaldehyde ortho-Nitrobenzaldehyde o-Nitrobenzaldehyde | |||
| Identifiers | |||
3D model (JSmol) |
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| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.008.206 | ||
| EC Number |
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PubChem CID |
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| UNII | |||
CompTox Dashboard (EPA) |
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| Properties | |||
| C7H5NO3 | |||
| Molar mass | 151.12 g/mol | ||
| Appearance | Pale yellow crystalline powder | ||
| Melting point | 43 °C (109 °F; 316 K) | ||
| Boiling point | 152 °C (306 °F; 425 K) | ||
| Insoluble | |||
| −68.23·10−6 cm3/mol | |||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards |
Harmful, Potentially mutagenic | ||
| GHS labelling:[1] | |||
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| Warning | |||
| H302, H315, H319, H335, H412 | |||
| P261, P264, P270, P271, P273, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501 | |||
| NFPA 704 (fire diamond) | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis
The nitration of benzaldehyde produces mostly 3-nitrobenzaldehyde. Partly for this reason, 2-nitrobenzaldehyde is prepared by indirect routes.[3] The main routes to nitrobenzaldehyde begin with the nitration of styrene or cinnamic acid followed by the conversions of the resulting 2-nitrostyrene and 2-nitrocinnamic acids, respectively. Cinnamaldehyde can also be nitrated in high-yield to 2-nitrocinnamaldehyde.[4] 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.[5]
2-Nitrotoluene can be oxidized 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.[8]
Uses
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[9][10] The method was abandoned in the early part of the 20th century, being replaced by routes from aniline.[11]
Baeyer-Drewson Indigo Synthesis
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 functions.[12][13]