In organic chemistry, ammoxidation is a process for the production of nitriles (R−C≡N) using ammonia (NH3) and oxygen (O2). It is sometimes called the SOHIO process, acknowledging that ammoxidation was developed at Standard Oil of Ohio. [1] [2] The usual substrates are alkenes. Several million tons of acrylonitrile are produced in this way annually: [3] [4]
Ammoxidation of alkenes exploits the weak C-H bonds that are located in the allylic position of unsaturated hydrocarbons. Benzylic C-H bonds are also susceptible to ammoxidation, reflecting the weakness of their C-H bonds. Benzonitrile is produced from toluene, and phthalonitriles are produced from xylenes. The reaction represents a partial oxidation. Many byproducts are generated, but the feedstocks are often simple, which compensates for these losses. Additionally, some byproducts are useful or recyclable. For the production of acrylonitrile, byproducts include hydrogen cyanide, acrolein, and the solvent acetonitrile.
The reaction tolerates heteroatoms and substituents. Cyanopyridines (e.g. 3-cyanopyridine, the precursor to niacin) is produced from methylpyridines. 2- and 4-Chlorotoluene are converted to 2-chlorobenzonitrile and 4-chlorobenzonitrile, respectively. [5]
Typical catalysts are the oxides of vanadium and molybdenum. The original catalyst discovered at Sohio was bismuth phosphomolybdate (BiPMo12O40). [1] π-Allyl complexes are assumed as intermediates. [6] [5]
Instead of alkenes, alcohols and aldehydes are competent substrates:
These substrates are usually more expensive than the alkenes, so they are less common. The nitrile process is used industrially to produce nitriles from fatty acids:
Hydrogen cyanide is prepared by an ammoxidation-like reaction of methane, the Andrussov oxidation:
In chemistry, amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines, trimethylamine, and aniline. Inorganic derivatives of ammonia are also called amines, such as monochloramine.
An oxide is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al2O3 that protects the foil from further oxidation.
Ethylene oxide is an organic compound with the formula C2H4O. It is a cyclic ether and the simplest epoxide: a three-membered ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sweet odor. Because it is a strained ring, ethylene oxide easily participates in a number of addition reactions that result in ring-opening. Ethylene oxide is isomeric with acetaldehyde and with vinyl alcohol. Ethylene oxide is industrially produced by oxidation of ethylene in the presence of a silver catalyst.
Acrylonitrile is an organic compound with the formula CH2CHCN and the structure H2C=CH−C≡N. It is a colorless, volatile liquid. It has a pungent odor of garlic or onions. Its molecular structure consists of a vinyl group linked to a nitrile. It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. It is reactive and toxic at low doses.
In organic chemistry, a nitrile is any organic compound that has a −C≡N functional group. The name of the compound is composed of a base, which includes the carbon of the −C≡N, suffixed with "nitrile", so for example CH3CH2C≡N is called "propionitrile". The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons.
In organic chemistry, an allyl group is a substituent with the structural formula −CH2−HC=CH2. It consists of a methylene bridge attached to a vinyl group. The name is derived from the scientific name for garlic, Allium sativum. In 1844, Theodor Wertheim isolated an allyl derivative from garlic oil and named it "Schwefelallyl". The term allyl applies to many compounds related to H2C=CH−CH2, some of which are of practical or of everyday importance, for example, allyl chloride.
In chemistry, a trimer is a molecule or polyatomic anion formed by combination or association of three molecules or ions of the same substance. In technical jargon, a trimer is a kind of oligomer derived from three identical precursors often in competition with polymerization.
Butyronitrile or butanenitrile or propyl cyanide, is a nitrile with the formula C3H7CN. This colorless liquid is miscible with most polar organic solvents.
Chlorotoluenes are aryl chlorides based on toluene in which at least one aromatic hydrogen atom is replaced with a chlorine atom. They have the general formula C7H8–nCln, where n = 1–5 is the number of chlorine atoms.
In chemistry, carbonylation refers to reactions that introduce carbon monoxide (CO) into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbonylation also refers to oxidation of protein side chains.
Glycolonitrile, also called hydroxyacetonitrile or formaldehyde cyanohydrin, is the organic compound with the formula HOCH2CN. It is the simplest cyanohydrin and it is derived from formaldehyde. It is a colourless liquid that dissolves in water and ether. Because glycolonitrile decomposes readily into formaldehyde and hydrogen cyanide, it is listed as an extremely hazardous substance. In January 2019, astronomers reported the detection of glycolonitrile, another possible building block of life among other such molecules, in outer space.
Aminoacetonitrile is the organic compound with the formula H2N−CH2−C≡N. The compound is a colorless liquid. It is unstable at room temperature, owing to the incompatibility of the amine nucleophile and the nitrile electrophile. For this reason it is usually encountered as the chloride and bisulfate salts of the ammonium derivative, i.e., [NCCH2NH3]+Cl− and [NCCH2NH3]+HSO4−.
Propionitrile, also known as ethyl cyanide and propanenitrile, is an organic compound with the formula CH3CH2CN. It is a simple aliphatic nitrile. The compound is a colourless, water-soluble liquid. It is used as a solvent and a precursor to other organic compounds.
3-Chloropropionitrile is an organic compound with the formula ClCH2CH2CN. A colorless liquid, it is prepared by the reaction of hydrogen chloride with acrylonitrile. It is used commercially as a precursor to the drug famotidine.
2,6-Dimethylnaphthalene (2,6-DMN) is a polycyclic aromatic hydrocarbon. It is one of the ten dimethylnaphthalene isomers, which are derived from naphthalene by the addition of two methyl groups.
Oxidative carbonylation is a class of reactions that use carbon monoxide in combination with an oxidant to generate esters and carbonate esters. These transformations utilize transition metal complexes as homogeneous catalysts. Many of these reactions employ palladium catalysts. Mechanistically, these reactions resemble the Wacker process.
Isophthalonitrile is an organic compound with the formula C6H4(CN)2. Two other isomers exist, phthalonitrile and terephthalonitrile. All three isomers are produced commercially by ammoxidation of the corresponding xylene isomers. Isophthalonitrile is a colorless or white solid with low solubility in water. Hydrogenation of isophthalonitrile affords m-xylylenediamine, a curing agent in epoxy resins and a component of some urethanes.
1,4-Dicyanobenzene is an organic compound with the formula C6H4(CN)2. Two other isomers exist, phthalonitrile and isophthalonitrile. All three isomers are produced commercially by ammoxidation of the corresponding xylene isomers. 1,4-Dicyanobenzene is a colorless or white solid with low solubility in water. Hydrogenation of isophthalonitrile affords p-xylylenediamine.
2-Chlorobenzonitrile is an organic compound with the formula ClC6H4CN. It is a white solid. The compound, one of three isomers of chlorobenzonitrile, is produced industrially by ammoxidation of 2-chlorotoluene. The compound is of commercial interest as a precursor to 2-amino-5-nitrobenzonitrile, a precursor to dyes.
4-Chlorobenzonitrile is an organic compound with the formula ClC6H4CN. It is a white solid. The compound, one of three isomers of chlorobenzonitrile, is produced industrially by ammoxidation of 4-chlorotoluene. The compound is of commercial interest as a precursor to pigments.
