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, an ester is a compound derived from an oxoacid in which at least one hydroxyl group is replaced by an alkoxy group, as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils.
An oxide is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) 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 (called a passivation layer) that protects the foil from further corrosion.
Acetonitrile, often abbreviated MeCN, is the chemical compound with the formula CH3CN and structure H3C−C≡N. This colourless liquid is the simplest organic nitrile. It is produced mainly as a byproduct of acrylonitrile manufacture. It is used as a polar aprotic solvent in organic synthesis and in the purification of butadiene. The N≡C−C skeleton is linear with a short C≡N distance of 1.16 Å.
In chemistry, a hydration reaction is a chemical reaction in which a substance combines with water. In organic chemistry, water is added to an unsaturated substrate, which is usually an alkene or an alkyne. This type of reaction is employed industrially to produce ethanol, isopropanol, and butan-2-ol.
Acrylonitrile is an organic compound with the formula CH2CHCN and the structure H2C=CH−C≡N. It is a colorless, volatile liquid although commercial samples can be yellow due to impurities. It has a pungent odor of garlic or onions. In terms of its molecular structure, it 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. Acrylonitrile was first synthesized by the French chemist Charles Moureu (1863–1929) in 1893.
In organic chemistry, a nitrile is any organic compound that has a −C≡N functional group. 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 chemistry, a dehydration reaction is a chemical reaction that involves the loss of water from the reacting molecule or ion. Dehydration reactions are common processes, the reverse of a hydration reaction.
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.
Chlorotoluene is a group of three isomeric chemical compounds. They consist of a disubstituted benzene ring with one chlorine atom and one methyl group.
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 NCCH2NH2. 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.
m-Xylylenediamine is an organic compound with the formula C6H4(CH2NH2)2. A colorless oily liquid, it is produced by hydrogenation of isophthalonitrile.
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.
4-Chlorobutyronitrile is the organic compound with the formula ClCH2CH2CH2CN. With both chloro and cyano functional groups, it is a bifunctional molecule. This colorless liquid is prepared by the reaction of sodium cyanide with 1-bromo-3-chloropropane.
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.
