Oxidative coupling

Last updated

Oxidative coupling in chemistry is a coupling reaction of two molecular entities through an oxidative process. Usually oxidative couplings are catalysed by a transition metal complex like in classical cross-coupling reactions, although the underlying mechanism is different due to the oxidation process that requires an external (or internal) oxidant. [1] [2] Many such couplings utilize dioxygen as the stoichiometric oxidant but proceed by electron transfer. [3]

Contents

C-C Couplings

Many oxidative couplings generate new C-C bonds. Early examples involve coupling of terminal alkynes: [4]

2 RC≡CH + 2 Cu(I) → RC≡C-C≡CR + 2 Cu + 2 H+

Aromatic coupling

Idealized lignin structure; aryl-aryl linkages arise from enzymatic oxidative couplings. Lignin structure.svg
Idealized lignin structure; aryl-aryl linkages arise from enzymatic oxidative couplings.

In oxidative aromatic coupling the reactants are electron-rich aromatic compounds. Typical substrates are phenols and typical catalysts are copper and iron compounds and enzymes. [6] The first reported synthetic application dates back to 1868 with Julius Löwe and the synthesis of ellagic acid by heating gallic acid with arsenic acid or silver oxide. [7] Another reaction is the synthesis of 1,1'-Bi-2-naphthol from 2-naphthol by iron chloride, discovered in 1873 by Alexander Dianin [8] (S)-BINOL can be prepared directly from an asymmetric oxidative coupling of 2-naphthol with copper(II) chloride. [9] CuCl2 naphthol coupling.png

Coupling of methane

Coupling reactions involving methane are highly sought, related to C1 chemistry because C2 derivatives are far more valuable than methane. The oxidative coupling of methane gives ethylene: [10] [11]

2CH
4
+ O
2
C
2
H
4
+ 2H
2
O

Other oxidative couplings

"Coupling" in water electrolysis. Electrolysis of Water.png
"Coupling" in water electrolysis.

The oxygen evolution reaction entails, in effect, the oxidative coupling of water molecules to give O2.

Related Research Articles

Iron(III) chloride describes the inorganic compounds with the formula FeCl3(H2O)x. Also called ferric chloride, these compounds are some of the most important and commonplace compounds of iron. They are available both in anhydrous and in hydrated forms which are both hygroscopic. They feature iron in its +3 oxidation state. The anhydrous derivative is a Lewis acid, while all forms are mild oxidizing agents. It is used as a water cleaner and as an etchant for metals.

The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877 to attach substituents to an aromatic ring. Friedel–Crafts reactions are of two main types: alkylation reactions and acylation reactions. Both proceed by electrophilic aromatic substitution.

The Suzuki reaction or Suzuki coupling is an organic reaction that uses a palladium complex catalyst to cross-couple a boronic acid to an organohalide. It was first published in 1979 by Akira Suzuki, and he shared the 2010 Nobel Prize in Chemistry with Richard F. Heck and Ei-ichi Negishi for their contribution to the discovery and development of noble metal catalysis in organic synthesis. This reaction is sometimes telescoped with the related Miyaura borylation; the combination is the Suzuki–Miyaura reaction. It is widely used to synthesize polyolefins, styrenes, and substituted biphenyls.

The Sandmeyer reaction is a chemical reaction used to synthesize aryl halides from aryl diazonium salts using copper salts as reagents or catalysts. It is an example of a radical-nucleophilic aromatic substitution. The Sandmeyer reaction provides a method through which one can perform unique transformations on benzene, such as halogenation, cyanation, trifluoromethylation, and hydroxylation.

<span class="mw-page-title-main">Wacker process</span> Chemical reaction

The Wacker process or the Hoechst-Wacker process refers to the oxidation of ethylene to acetaldehyde in the presence of palladium(II) chloride and copper(II) chloride as the catalyst. This chemical reaction was one of the first homogeneous catalysis with organopalladium chemistry applied on an industrial scale.

1,1-Bi-2-naphthol (BINOL) is an organic compound that is often used as a ligand for transition-metal catalysed asymmetric synthesis. BINOL has axial chirality and the two enantiomers can be readily separated and are stable toward racemisation. The specific rotation of the two enantiomers is 35.5° (c = 1 in THF), with the R enantiomer being the dextrorotary one. BINOL is a precursor for another chiral ligand called BINAP. The volumetric mass density of the two enantiomers is 0.62 g cm−3.

<span class="mw-page-title-main">Diazonium compound</span> Group of organonitrogen compounds

Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group [R−N+≡N]X where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide.

In organic chemistry, an azo coupling is an reaction between a diazonium compound and another aromatic compound that produces an azo compound. In this electrophilic aromatic substitution reaction, the aryldiazonium cation is the electrophile, and the activated carbon acts as a nucleophile. The desired azo compound is synthesized from this para substitution reaction. In most cases, including the examples below, the diazonium compound is also aromatic.

A dendralene is a discrete acyclic cross-conjugated polyene. The simplest dendralene is buta-1,3-diene (1) or [2]dendralene followed by [3]dendralene (2), [4]dendralene (3) and [5]dendralene (4) and so forth. [2]dendralene (butadiene) is the only one not cross-conjugated.

In organic chemistry, the Arndt–Eistert reaction is the conversion of a carboxylic acid to its homologue. Named for the German chemists Fritz Arndt (1885–1969) and Bernd Eistert (1902–1978), the method entails treating an acid chlorides with diazomethane. It is a popular method of producing β-amino acids from α-amino acids.

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

Isatin, also known as tribulin, is an organic compound derived from indole with formula C8H5NO2. The compound was first obtained by Otto Linné Erdman and Auguste Laurent in 1840 as a product from the oxidation of indigo dye by nitric acid and chromic acids.

<span class="mw-page-title-main">Scholl reaction</span>

The Scholl reaction is a coupling reaction between two arene compounds with the aid of a Lewis acid and a protic acid. It is named after its discoverer, Roland Scholl, a Swiss chemist.

<span class="mw-page-title-main">Organocopper chemistry</span> Compound with carbon to copper bonds

Organocopper chemistry is the study of the physical properties, reactions, and synthesis of organocopper compounds, which are organometallic compounds containing a carbon to copper chemical bond. They are reagents in organic chemistry.

[n]Radialenes are alicyclic organic compounds containing n cross-conjugated exocyclic double bonds. The double bonds are commonly alkene groups but those with a carbonyl (C=O) group are also called radialenes. For some members the unsubstituted parent radialenes are elusive but many substituted derivatives are known.

In organic chemistry, the Buchwald–Hartwig amination is a chemical reaction for the synthesis of carbon–nitrogen bonds via the palladium-catalyzed coupling reactions of amines with aryl halides. Although Pd-catalyzed C–N couplings were reported as early as 1983, Stephen L. Buchwald and John F. Hartwig have been credited, whose publications between 1994 and the late 2000s established the scope of the transformation. The reaction's synthetic utility stems primarily from the shortcomings of typical methods for the synthesis of aromatic C−N bonds, with most methods suffering from limited substrate scope and functional group tolerance. The development of the Buchwald–Hartwig reaction allowed for the facile synthesis of aryl amines, replacing to an extent harsher methods while significantly expanding the repertoire of possible C−N bond formations.

The Glaser coupling is a type of coupling reaction. It is by far the oldest acetylenic coupling and is based on cuprous salts like copper(I) chloride or copper(I) bromide and an additional oxidant like oxygen. The base in its original scope is ammonia. The solvent is water or an alcohol. The reaction was first reported by Carl Andreas Glaser in 1869. He suggested the following process for his way to diphenylbutadiyne:

Unlike its lighter congeners, the halogen iodine forms a number of stable organic compounds, in which iodine exhibits higher formal oxidation states than -1 or coordination number exceeding 1. These are the hypervalent organoiodines, often called iodanes after the IUPAC rule used to name them.

Organoiron chemistry is the chemistry of iron compounds containing a carbon-to-iron chemical bond. Organoiron compounds are relevant in organic synthesis as reagents such as iron pentacarbonyl, diiron nonacarbonyl and disodium tetracarbonylferrate. Although iron is generally less active in many catalytic applications, it is less expensive and "greener" than other metals. Organoiron compounds feature a wide range of ligands that support the Fe-C bond; as with other organometals, these supporting ligands prominently include phosphines, carbon monoxide, and cyclopentadienyl, but hard ligands such as amines are employed as well.

The oxidative coupling of methane (OCM) is a potential chemical reaction studied in the 1980s for the direct conversion of natural gas, primarily consisting of methane, into value-added chemicals. Although the reaction would have strong economics if practicable, no effective catalysts are known, and thermodynamic arguments suggest none can exist.

Decarboxylative cross coupling reactions are chemical reactions in which a carboxylic acid is reacted with an organic halide to form a new carbon-carbon bond, concomitant with loss of CO2. Aryl and alkyl halides participate. Metal catalyst, base, and oxidant are required.

References

  1. Oxidative Cross-Coupling Reactions. Aiwen Lei, Wei Shi, Chao Liu, Wei Liu, Hua Zhang, Chuan He, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany (2017). doi : 10.1002/9783527680986
  2. Ignacio Funes-Ardoiz; Feliu Maseras (2018). "Oxidative Coupling Mechanisms: Current State of Understanding". ACS Catalysis. 8 (2): 1161–1172. doi: 10.1021/acscatal.7b02974 .
  3. IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). doi : 10.1351/goldbook
  4. Alison E. Wendlandt; Alison M. Suess; Shannon S. Stahl (2011). "Copper-Catalyzed Aerobic Oxidative C-H Functionalizations: Trends and Mechanistic Insights". Angew. Chem. Int. Ed. 50 (47): 11062–11087. doi:10.1002/anie.201103945. PMID   22034061.
  5. Lebo, Stuart E. Jr.; Gargulak, Jerry D.; McNally, Timothy J. (2001). "Lignin". Kirk-Othmer Encyclopedia of Chemical Technology. Kirk‑Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. doi:10.1002/0471238961.12090714120914.a01.pub2. ISBN   0-471-23896-1 . Retrieved 2007-10-14.
  6. Grzybowski, M., Skonieczny, K., Butenschön, H. and Gryko, D. T. (2013), Comparison of Oxidative Aromatic Coupling and the Scholl Reaction Angew. Chem. Int. Ed., 52: 9900–9930. doi : 10.1002/anie.201210238
  7. Löwe, Zeitschrift für Chemie, 1868, 4, 603
  8. A. P. Dianin, Zh. Russ. Fiz.-Khim. O-va. 1874 , 183
  9. Brussee, J.; Jansen, A. C. A. (1983). "A highly stereoselective synthesis of S-(−)-[1,1′-binaphthalene]-2,2′-diol". Tetrahedron Letters. 24 (31): 3261–3262. doi:10.1016/S0040-4039(00)88151-4.
  10. Zhang, Q. (2003). "Recent Progress in Direct Partial Oxidation of Methane to Methanol". J. Natural Gas Chem. 12: 81–89.
  11. Olah, G., Molnar, A. "Hydrocarbon Chemistry" John Wiley & Sons, New York, 2003. ISBN   978-0-471-41782-8.