2-nitrobenzaldehyde

2-Nitrobenzaldehyde

2-Nitrobenzaldehyde

Chemical compound

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.

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Synthesis

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.[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]

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.[6] The 2-nitrotoluene can then be oxidized to yield 2-nitrobenzaldehyde.[7][8]

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.[9]

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.[10] For this reason, the nitration of benzaldehyde to yield 2-nitrobenzaldehyde is not cost-effective.

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.[11][12][13][14] The method was abandoned in the early part of the 20th century, being replaced by routes from aniline.[15]

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.[16][17]

References

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    2-Nitrobenzaldehyde
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    "2-Nitrobenzaldehyde MSDS". Archived from the original on 2011-07-07. Retrieved 2009-07-18.
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    "2-Nitrobenzaldehyde". pubchem.ncbi.nlm.nih.gov.
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    o-NITROCINNAMALDEHYDE, nitration of cinnamaldehyde, organic-synthesis
  5. [5]
    Feng, Bo; Hou, Zhenshan; Wang, Xiangrui; Hu, Yu; Li, Huan; Qiao, Yunxiang (2009-09-01). "Selective aerobic oxidation of styrene to benzaldehyde catalyzed by water-soluble palladium(II) complex in water". Green Chemistry. 11 (9): 1446–1452. doi:10.1039/B900807A. ISSN 1463-9270.
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    http://www.thecatalyst.org/experiments/AndersonS/AndersonS.doc Product Distribution in the Nitration of Toluene, Steven W. Anderson, January 7, 1999
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    Synthesis of 2-Nitrobenzaldehyde from 2-Nitrotoluene Archived 2011-06-05 at the Wayback Machine, Alexander Popkov
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    "o-Nitrobenzaldehyde". Archived from the original on 2011-06-06. Retrieved 2009-07-21.
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    "Process for the Preparation of 2-Nitrobenzaldehyde". Retrieved 2010-10-18.
  10. [10]
    Structure of Benzene, California State University Dominguez Hills
  11. [11]
    See Baeyer-Drewson indigo synthesis
  12. [12]
    Synthesis of Indigo Archived 2010-06-20 at the Wayback Machine
  13. [13]
    "Indigo Synthesis". Archived from the original on 2011-07-20. Retrieved 2009-07-18.
  14. [14]
    "Synthesis of Indigo and Vat Dyeing" (PDF). Archived from the original (PDF) on 2011-07-20. Retrieved 2009-07-18.
  15. [15]
    Wiley-VCH, ed. (2003-03-11). Ullmann's Encyclopedia of Industrial Chemistry (1 ed.). Wiley. doi:10.1002/14356007.a14_149.pub2. ISBN 978-3-527-30385-4.
  16. [16]
    Šebej, Peter; Šolomek, Tomáš; Hroudná, Ľubica; Brancová, Pavla; Klán, Petr (2009). "Photochemistry of 2-Nitrobenzylidene Acetals". J. Org. Chem. 74 (22): 8647–8658. doi:10.1021/jo901756r. PMID 19824651.
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    Kristine L. Willett; Ronald A. Hites (2000). "Chemical Actinometry: Using o-Nitrobenzaldehyde to Measure Lamp Intensity in Photochemical Experiments". J. Chem. Educ. 77 (7): 900. Bibcode:2000JChEd..77..900W. doi:10.1021/ed077p900.
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