Nitrosobenzene

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Nitrosobenzene
Nitrosobenzene.png
Nitrosobenzene-3D-balls.png
Names
Preferred IUPAC name
Nitrosobenzene
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.008.721 OOjs UI icon edit-ltr-progressive.svg
KEGG
PubChem CID
RTECS number
  • DA6497525
UNII
  • InChI=1S/C6H5NO/c8-7-6-4-2-1-3-5-6/h1-5H Yes check.svgY
    Key: NLRKCXQQSUWLCH-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C6H5NO/c8-7-6-4-2-1-3-5-6/h1-5H
    Key: NLRKCXQQSUWLCH-UHFFFAOYAR
Properties
C6H5NO
Molar mass 107.112 g·mol−1
AppearanceDark green solid (freshly sublimed monomer); pale yellow solid (dimeric form); bright green solution (light sensitive)
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)
Low
Solubility in other solventsSol. in organic solvents
-59.1·10−6 cm3/mol
Structure
N is sp2
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
toxic
GHS labelling:
GHS-pictogram-skull.svg
Danger
H301, H312, H332
P261, P264, P270, P271, P280, P301+P310, P302+P352, P304+P312, P304+P340, P312, P321, P322, P330, P363, P405, P501
Related compounds
Related compounds
Nitrobenzene
Aniline
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Nitrosobenzene is the organic compound with the formula C6H5NO. It is one of the prototypical organic nitroso compounds. Characteristic of its functional group, it is a dark green species that exists in equilibrium with its pale yellow dimer. Both monomer and dimer are diamagnetic.

Monomer-dimer equilibrium

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 dilute solution or at higher temperatures. The dimers can be formulated as Ar(O)N+=N+(O)Ar. They exist as cis- and trans-isomers due to the presence of the N–N double bond. The dimers are sometimes called azobenzenedioxides. The cis-trans isomerization occurs via the intermediacy of the monomer. [1]

In the case of nitrosobenzene itself, the metastable monomeric form could be prepared by sublimation onto a cold finger. The monomeric material is selectively sublimed due to its lower molecular weight and is collected on a cold finger as lustrous, dark green crystals. Over time, the monomeric material dimerizes to give the parent azobenzene dioxide as a pale yellow solid. As dictated by Le Chatelier's principle, nitrosobenzene exists in the solution phase as a mixture of monomer and dimer in dynamic equilibrium whose composition is dependent on temperature (monomer favored at higher temperature) and concentration (monomer favored at low concentration), as well as the identity of the medium (gas phase or solvent). [2]

Structure of 2-nitrosotoluene dimer. VIYMEX.png
Structure of 2-nitrosotoluene dimer.

Preparation

Nitrosobenzene was first prepared by Adolf von Baeyer by the reaction of diphenylmercury and nitrosyl bromide: [4]

(C6H5)2Hg + BrNO → C6H5NO + C6H5HgBr

A modern synthesis entails reduction of nitrobenzene to phenylhydroxylamine (C6H5NHOH) which is then oxidized by sodium dichromate (Na2Cr2O7). [5]

Nitrosobenzene can also be prepared by oxidation of aniline using peroxymonosulfuric acid (Caro's acid) [6] or potassium peroxymonosulfate under biphasic conditions. [7] It is usually purified by sublimation or by steam distillation, where it comes over as a green liquid that solidifies to a colorless solid.

Characteristic reactions

Nitrosobenzene undergoes Diels–Alder reactions with dienes. [8] Condensation with anilines affords azobenzene derivatives in a reaction known as the Mills reaction or Baeyer-Mills reaction. [9] Reduction of nitrosobenzene produces aniline.

Baeyer-Mills Mechanismus.svg

Most characteristically, nitrosobenzene condenses with active methylene groups, such as those of malonic esters and phenylacetonitrile. Phenylacetonitrile (PhCH2CN) gives the imine (PhC(CN)=NPh) in a reaction known as the Ehrlich-Sachs reaction: [10]

ES reaction.png

Sometimes condensation with active methylene compounds gives products of O-nitroso-aldol reaction: [11]

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

Related Research Articles

<span class="mw-page-title-main">Diene</span> Covalent compound that contains two double bonds

In organic chemistry, a diene ; also diolefin, dy-OH-lə-fin) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms. They thus contain two alkene units, with the standard prefix di of systematic nomenclature. As a subunit of more complex molecules, dienes occur in naturally occurring and synthetic chemicals and are used in organic synthesis. Conjugated dienes are widely used as monomers in the polymer industry. Polyunsaturated fats are of interest to nutrition.

In chemistry, dimerization refers to the process of joining two molecular entities by bonds. The resulting bonds can be either strong or weak. Many symmetrical chemical species are described as dimers, even when the monomer is unknown or highly unstable.

The aldol reaction is a reaction that combines two carbonyl compounds to form a new β-hydroxy carbonyl compound.

A diol is a chemical compound containing two hydroxyl groups. An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified.

<span class="mw-page-title-main">Organolithium reagent</span> Chemical compounds containing C–Li bonds

In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.

<span class="mw-page-title-main">Nitrobenzene</span> Chemical compound

Nitrobenzene is an organic compound with the chemical formula C6H5NO2. It is a water-insoluble pale yellow oil with an almond-like odor. It freezes to give greenish-yellow crystals. It is produced on a large scale from benzene as a precursor to aniline. In the laboratory, it is occasionally used as a solvent, especially for electrophilic reagents.

<span class="mw-page-title-main">Nitro compound</span> Organic compound containing an −NO₂ group

In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups. The nitro group is one of the most common explosophores used globally. The nitro group is also strongly electron-withdrawing. Because of this property, C−H bonds alpha (adjacent) to the nitro group can be acidic. For similar reasons, the presence of nitro groups in aromatic compounds retards electrophilic aromatic substitution but facilitates nucleophilic aromatic substitution. Nitro groups are rarely found in nature. They are almost invariably produced by nitration reactions starting with nitric acid.

The Robinson annulation is a chemical reaction used in organic chemistry for ring formation. It was discovered by Robert Robinson in 1935 as a method to create a six membered ring by forming three new carbon–carbon bonds. The method uses a ketone and a methyl vinyl ketone to form an α,β-unsaturated ketone in a cyclohexane ring by a Michael addition followed by an aldol condensation. This procedure is one of the key methods to form fused ring systems.

<span class="mw-page-title-main">Dicyclopentadiene</span> Chemical compound

Dicyclopentadiene, abbreviated DCPD, is a chemical compound with formula C10H12. At room temperature, it is a white brittle wax, although lower purity samples can be straw coloured liquids. The pure material smells somewhat of soy wax or camphor, with less pure samples possessing a stronger acrid odor. Its energy density is 10,975 Wh/l. Dicyclopentadiene is a co-produced in large quantities in the steam cracking of naphtha and gas oils to ethylene. The major use is in resins, particularly, unsaturated polyester resins. It is also used in inks, adhesives, and paints.

Dynamic covalent chemistry (DCvC) is a synthetic strategy employed by chemists to make complex molecular and supramolecular assemblies from discrete molecular building blocks. DCvC has allowed access to complex assemblies such as covalent organic frameworks, molecular knots, polymers, and novel macrocycles. Not to be confused with dynamic combinatorial chemistry, DCvC concerns only covalent bonding interactions. As such, it only encompasses a subset of supramolecular chemistries.

<span class="mw-page-title-main">Alkylimino-de-oxo-bisubstitution</span> Organic reaction of carbonyl compounds with amines to imines

In organic chemistry, alkylimino-de-oxo-bisubstitution is the organic reaction of carbonyl compounds with amines to imines. The reaction name is based on the IUPAC Nomenclature for Transformations. The reaction is acid catalyzed and the reaction type is nucleophilic addition of the amine to the carbonyl compound followed by transfer of a proton from nitrogen to oxygen to a stable hemiaminal or carbinolamine. With primary amines water is lost in an elimination reaction to an imine. With aryl amines especially stable Schiff bases are formed.

<span class="mw-page-title-main">Nitroso</span> Class of functional groups with a –N=O group attached

In organic chemistry, nitroso refers to a functional group in which the nitric oxide group is attached to an organic moiety. As such, various nitroso groups can be categorized as C-nitroso compounds, S-nitroso compounds, N-nitroso compounds, and O-nitroso compounds.

<span class="mw-page-title-main">Azoxy compounds</span> Chemical compound of the form R–N=N(–O)–R

In chemistry, azoxy compounds are a group of organic compounds sharing a common functional group with the general structure R−N=N+(−O)−R. They are considered N-oxides of azo compounds. Azoxy compounds are 1,3-dipoles and cycloadd to double bonds. Most azoxy-containing compounds have aryl substituents.

<span class="mw-page-title-main">Doebner–Miller reaction</span>

The Doebner–Miller reaction is the organic reaction of an aniline with α,β-unsaturated carbonyl compounds to form quinolines.

<span class="mw-page-title-main">Aluminium iodide</span> Chemical compound

Aluminium iodide is a chemical compound containing aluminium and iodine. Invariably, the name refers to a compound of the composition AlI
3
, formed by the reaction of aluminium and iodine or the action of HI on Al metal. The hexahydrate is obtained from a reaction between metallic aluminum or aluminum hydroxide with hydrogen iodide or hydroiodic acid. Like the related chloride and bromide, AlI
3
is a strong Lewis acid and will absorb water from the atmosphere. It is employed as a reagent for the scission of certain kinds of C-O and N-O bonds. It cleaves aryl ethers and deoxygenates epoxides.

2-Methyl-2-nitrosopropane (MNP or t-nitrosobutane) is the organic compound with the formula (CH3)3CNO. It is a blue liquid that is used in chemical research as a spin trap, i.e. it binds to radicals.

Methanediol, also known as formaldehyde monohydrate or methylene glycol, is an organic compound with chemical formula CH2(OH)2. It is the simplest geminal diol. In aqueous solutions it coexists with oligomers. The compound is closely related and convertible to the industrially significant derivatives paraformaldehyde, formaldehyde, and 1,3,5-trioxane.

<span class="mw-page-title-main">Torreyanic acid</span> Group of chemical compounds

Torreyanic acid is a dimeric quinone first isolated and by Lee et al. in 1996 from an endophyte, Pestalotiopsis microspora. This endophyte is likely the cause of the decline of Florida torreya, an endangered species that is related to the taxol-producing Taxus brevifolia. The natural product was found to be cytotoxic against 25 different human cancer cell lines with an average IC50 value of 9.4 µg/mL, ranging from 3.5 (NEC) to 45 (A549) µg/mL. Torreyanic acid was found to be 5-10 times more potent in cell lines sensitive to protein kinase C (PKC) agonists, 12-o-tetradecanoyl phorbol-13-acetate (TPA), and was shown to cause cell death via apoptosis. Torreyanic acid also promoted G1 arrest of G0 synchronized cells at 1-5 µg/mL levels, depending on the cell line. It has been proposed that the eukaryotic translation initiation factor EIF-4a is a potential biochemical target for the natural compound.

<span class="mw-page-title-main">Plumbylene</span> Divalent organolead(II) analogues of carbenes

Plumbylenes (or plumbylidenes) are divalent organolead(II) analogues of carbenes, with the general chemical formula, R2Pb, where R denotes a substituent. Plumbylenes possess 6 electrons in their valence shell, and are considered open shell species.

<span class="mw-page-title-main">Azobenzene dioxide</span> Chemical compound

Azobenzene dioxide is the organic compound with the formula (C6H5N )2. Both cis and trans isomers are known. The cis isomer has been crystallized. It is colorless.

References

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  2. Varga, Katarina; Biljan, Ivana; Tomišić, Vladislav; Mihalić, Zlatko; Vančik, Hrvoj (8 March 2018). "Quantum Chemical Calculations of Monomer–Dimer Equilibria of Aromatic C -Nitroso Compounds". The Journal of Physical Chemistry A. 122 (9): 2542–2549. Bibcode:2018JPCA..122.2542V. doi:10.1021/acs.jpca.7b12179. ISSN   1089-5639. PMID   29381362.
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  11. "Asymmetric O− and N− Nitroso Aldol Reaction – an efficient access to a-oxy and a-amino carbonyl compound" (PDF).