2-Nitrobenzaldehyde

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.

2-Nitrobenzaldehyde[1][2]
Skeletal formula of 2-nitrobenzaldehyde
Ball-and-stick model of the 2-nitrobenzaldehyde molecule
Names
Preferred IUPAC name
2-Nitrobenzaldehyde
Other names
Nitrobenzaldehyde
ortho-Nitrobenzaldehyde
o-Nitrobenzaldehyde
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.008.206
EC Number
  • 209-025-3
UNII
  • InChI=1S/C7H5NO3/c9-5-6-3-1-2-4-7(6)8(10)11/h1-5H checkY
    Key: CMWKITSNTDAEDT-UHFFFAOYSA-N checkY
  • InChI=1/C7H5NO3/c9-5-6-3-1-2-4-7(6)8(10)11/h1-5H
    Key: CMWKITSNTDAEDT-UHFFFAOYAD
  • O=[N+]([O-])c1ccccc1C=O
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:[3]
GHS07: Exclamation mark
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)
NFPA 704 four-colored diamond
2
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)
Infobox references

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
  1. 2-Nitrobenzaldehyde
  2. "2-Nitrobenzaldehyde MSDS". Archived from the original on 2011-07-07. Retrieved 2009-07-18.
  3. "2-Nitrobenzaldehyde". pubchem.ncbi.nlm.nih.gov.
  4. o-NITROCINNAMALDEHYDE, nitration of cinnamaldehyde, organic-synthesis
  5. Selective aerobic oxidation of styrene to benzaldehyde catalyzed by water-soluble palladium(II) complex in water, Bo Feng, Zhenshan Hou, Xiangrui Wang, Yu Hu, Huan Li and Yunxiang Qiao
  6. http://www.thecatalyst.org/experiments/AndersonS/AndersonS.html Product Distribution in the Nitration of Toluene, Steven W. Anderson, January 7, 1999
  7. Synthesis of 2-Nitrobenzaldehyde from 2-Nitrotoluene Archived 2011-06-05 at the Wayback Machine, Alexander Popkov
  8. "o-Nitrobenzaldehyde". Archived from the original on 2011-06-06. Retrieved 2009-07-21.
  9. "Process for the Preparation of 2-Nitrobenzaldehyde". Retrieved 2010-10-18.
  10. Structure of Benzene, California State University Dominguez Hills
  11. See Baeyer-Drewson indigo synthesis
  12. Synthesis of Indigo Archived 2010-06-20 at the Wayback Machine
  13. "Indigo Synthesis". Archived from the original on 2011-07-20. Retrieved 2009-07-18.
  14. "Synthesis of Indigo and Vat Dyeing" (PDF). Archived from the original (PDF) on 2011-07-20. Retrieved 2009-07-18.
  15. Elmar Steingruber "Indigo and Indigo Colorants" Ullmann's Encyclopedia of Industrial Chemistry 2004, Wiley-VCH, Weinheim. doi:10.1002/14356007.a14_149.pub2
  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.
  17. 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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