Nitrosobenzene is the organic compound

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 with the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 C₆H₅NO. The compound can be viewed as hybrid of singlet

Singlet oxygen

Singlet oxygen is the common name used for the diamagnetic form of molecular oxygen , which is less stable than the normal triplet oxygen. Because of its unusual properties, singlet oxygen can persist for over an hour at room temperature, depending on the environment...

 O₂ and azobenzene

Azobenzene

Azobenzene is a chemical compound composed of two phenyl rings linked by a N=N double bond. It is the best known example of an azo compound. The term 'azobenzene' or simply 'azo' is often used to refer to a wide class of molecules that share the core azobenzene structure, with different chemical...

. This diamagnetic

Diamagnetism

Diamagnetism is the property of an object which causes it to create a magnetic field in opposition to an externally applied magnetic field, thus causing a repulsive effect. Specifically, an external magnetic field alters the orbital velocity of electrons around their nuclei, thus changing the...

 species exists in equilibrium with its dimer.

Preparation

C₆H₅NO was first prepared by Adolf von Baeyer

Adolf von Baeyer

Johann Friedrich Wilhelm Adolf von Baeyer was a German chemist who synthesized indigo, and was the 1905 recipient of the Nobel Prize in Chemistry. Born in Berlin, he initially studied mathematics and physics at Berlin University before moving to Heidelberg to study chemistry with Robert Bunsen...

 by the reaction of diphenylmercury

Diphenylmercury

Diphenylmercury is a colourless, crystalline organomercury compound with the chemical formula C12H10Hg. It can be synthesised by the reaction of a 2:1 molar ratio of mercury chloride and methyltriphenyltin in ethanol...

 and nitrosyl bromide:

[C₆H₅]₂Hg + BrNO → C₆H₅NO + C₆H₅HgBr

The modern synthesis entails reduction of nitrobenzene to phenylhydroxylamine

Phenylhydroxylamine

Phenylhydroxylamine is the organic compound with the formula C6H5NHOH. It is an intermediate in the redox-related pair C6H5NH2 and C6H5NO. Phenylhydroxylamine should not be confused with its isomer α-phenylhydroxylamine or O-phenylhydroxylamine, is C6H5ONH2.-Preparation and derivatives:This...

, C₆H₅NHOH, which is then oxidized by Na₂Cr₂O₇

Sodium dichromate

Sodium dichromate is the chemical compound with the formula Na2Cr2O7. Usually, however, the salt is handled as its dihydrate Na2Cr2O7·2H2O. Virtually all chromium ore is processed via conversion to sodium dichromate. In this way, many millions of kilograms of sodium dichromate are produced...

. C₆H₅NO can also be prepared by oxidation of aniline using peroxymonosulfuric acid, Caro's acid. 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. Condensation with aniline

Aniline

Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...

s affords azobenzene

Azobenzene

Azobenzene is a chemical compound composed of two phenyl rings linked by a N=N double bond. It is the best known example of an azo compound. The term 'azobenzene' or simply 'azo' is often used to refer to a wide class of molecules that share the core azobenzene structure, with different chemical...

 derivatives (Mills reaction). Reduction of PhNO produces C₆H₅NH₂

Aniline

Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...

.

Most characteristically nitrosobenzene condenses

Condensation reaction

A condensation reaction is a chemical reaction in which two molecules or moieties combine to form one single molecule, together with the loss of a small molecule. When this small molecule is water, it is known as a dehydration reaction; other possible small molecules lost are hydrogen chloride,...

 with "active" methylene groups, e.g. of malonic esters, benzyl cyanide

Benzyl cyanide

Benzyl cyanide is an organic compound with the chemical formula C6H5CH2CN. This colorless oily aromatic liquid is a precursor to several derivatives.-Synthesis, reactions, and applications:...

 etc. For example, condensation with benzylcyanide PhCH₂CN gives the imine

Imine

An imine is a functional group or chemical compound containing a carbon–nitrogen double bond, with the nitrogen attached to a hydrogen atom or an organic group. If this group is not a hydrogen atom, then the compound is known as a Schiff base...

PhC(CN)=NPh (The Ehrlich-Sachs Reaction) :

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

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

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