3D model (JSmol)
|Molar mass||107.11 g·mol−1|
|Melting point||65 to 69 °C (149 to 156 °F; 338 to 342 K)|
|Boiling point||59 °C (138 °F; 332 K) (at 18 mmHg)|
|Solubility in other solvents||Sol. in organic solvents|
|N is sp2|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|‹See TfM› (what is ‹See TfM› ?)|
Nitrosobenzene is the organic compound with the formula C6H5NO. It is one of the prototypical organic nitroso compounds. It is a bright blue species that exists in equilibrium with its pale yellow dimer. Both monomer and dimer are diamagnetic.
Nitrosobenzene and other nitrosoarenes typically participate in a monomer-dimer equilibrium. The dimers are often favored in the solid state, whereas the deeply colored monomers are favored in dilution solution or at higher temperatures. The dimers can be formulated as Ph(O-)N+=N+(O-)Ph. They exist as cis- and trans-isomers. The dimers are sometimes called azobenzenedioxides. The cis-trans isomerization occurs via the intermediacy of the monomer.
- (C6H5)2Hg + BrNO → C6H5NO + C6H5HgBr
Nitrosobenzene can also be prepared by oxidation of aniline using peroxymonosulfuric acid (Caro's acid) or Oxone. It is usually purified by steam distillation, where it comes over as a green liquid that solidifies to a colorless solid.
Nitrosobenzene undergoes Diels-Alder reactions with dienes. Condensation with anilines affords azobenzene derivatives in a reaction known as the Mills reaction. Reduction of nitrosobenzene produces aniline.
Most characteristically, nitrosobenzene condenses with active methylene groups, such as those of malonic esters and benzyl cyanide. Benzylcyanide (PhCH2CN) gives the imine (PhC(CN)=NPh) in a reaction known as the Ehrlich-Sachs reaction:
- Ph–CH2-CN + Ph–NO → Ph–CH(CN)–N(OH)–Ph (oxyamination adduct) → PhC(CN)=N–Ph
Sometimes condensation with active methylene compounds gives products of O-nitroso-aldol reaction:
- R–CH2-CHO + Ph–NO → R–CH(CHO)–O–NHPh (aminoxylation adduct)
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