Nitrosobenzene

Nitrosobenzene
IUPAC name

Nitrosobenzene
Other names

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Identifiers
CAS number 586-96-9 Y
PubChem 11473
ChemSpider 10989 Y
KEGG C06876 Y
ChEBI CHEBI:27986 N
ChEMBL CHEMBL98797 Y
RTECS number DA6497525
Jmol-3D images Image 1
Properties
Molecular formula C6H5NO
Molar mass 107.11 g/mol
Appearance colourless solid
Density  ? g/cm3, ?
Melting point

65-69 °C
Boiling point

59 °C, 18 mm Hg
Solubility in water low
Solubility in other solvents sol. in organic solvents
Structure
Molecular shape N is sp2
Hazards
R-phrases 20/21-25
S-phrases 26-36/37-45
Main hazards toxic
Related compounds
Related compounds Nitrobenzene
Aniline
 N (verify) (what is: Y/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Nitrosobenzene is the organic compound with the formula C6H5NO. The compound can be viewed as hybrid of singlet O2 and azobenzene. This diamagnetic species exists in equilibrium with its dimer.

Contents

Preparation

C6H5NO was first prepared by Adolf von Baeyer by the reaction of diphenylmercury and nitrosyl bromide:[1]

[C6H5]2Hg + BrNO → C6H5NO + C6H5HgBr

The modern synthesis entails reduction of nitrobenzene to phenylhydroxylamine, C6H5NHOH, which is then oxidized by Na2Cr2O7.[2] C6H5NO can also be prepared by oxidation of aniline using peroxymonosulfuric acid, Caro's acid.[3] It is usually purified by steam distillation, where it comes over as a green liquid that solidifes to a colorless solid.

Characteristic reactions

The monomer undergoes Diels-Alder reactions with dienes.[4] Condensation with anilines affords azobenzene derivatives (Mills reaction)[5]. Reduction of PhNO produces C6H5NH2.

Most characteristically nitrosobenzene condenses with "active" methylene groups, e.g. of malonic esters, benzyl cyanide etc. For example, condensation with benzylcyanide PhCH2CN gives the imine PhC(CN)=NPh (The Ehrlich-Sachs Reaction)[6] :

Ph-CH2-CN + Ph-NO → Ph-CH(CN)-N(OH)-Ph (oxyamination adduct) → PhC(CN)=N-Ph

Sometimes condensation with "active" methylene compounds could give products of O-nitroso-aldol reaction [7]:

R-CH2-CHO + Ph-NO → R-CH(CHO)-O-NHPh (aminoxylation adduct)

See also

References

  1. ^ Baeyer, A. "Nitrosobenzol und Nitrosonaphtalin" Chemische Berichte 1874, volume 7, pp.1638–1640.
  2. ^ G. H. Coleman, C. M. McCloskey, F. A. Stuart (1955), "Nitrosobenzene", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV3P0668 ; Coll. Vol. 3: 668 
  3. ^ H. Caro, Z. angew. Chem., volume 11, p 845ff (1898).
  4. ^ H. Yamamoto, N. Momiyama "Rich Chemistry of Nitroso Compounds" Chemical Communications 2005, pp.3514–3525.
  5. ^ H. D. Anspon (1955), "p-Phenylazobenzoic Acid", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV3P0711 ; Coll. Vol. 3: 711 
  6. ^ H. Feuer in S. Patai (ed.) "The Chemistry of the Nitro and Nitroso Groups Part 1," Wiley: New York. pp. 278-283
  7. ^ Asymmetric O- and N- Nitroso Aldol Reaction - an efficient access to a-oxy and a-amino carbonyl compound