# Nitrile
A nitrile is an organic compound carrying a cyano group, −C≡N, in which a triply bonded nitrogen is attached to an sp-hybridized carbon that is in turn bonded to the rest of the molecule; the general structure is written R−C≡N[1](https://goldbook.iupac.org/terms/view/N04151/1000). Formally, nitriles are C-substituted derivatives of hydrocyanic acid, HC≡N[1](https://goldbook.iupac.org/terms/view/N04151/1000). The group is strongly polarized, with an electrophilic carbon atom, and this polarity governs most of its chemistry[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles). Simple nitriles such as acetonitrile are common laboratory solvents, while the group also appears in polymers, superglues, and a growing list of medicines[3](https://www.cdc.gov/niosh/npg/npgd0006.html) • [4](https://pubchem.ncbi.nlm.nih.gov/compound/Akrylonitril) • [5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9945868/).
| Key fact | Detail |
|---|---|
| Structure | R−C≡N; linear geometry with nitrogen bonded to an sp-hybridized carbon through a triple bond[1](https://goldbook.iupac.org/terms/view/N04151/1000) • [5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9945868/) |
| Nomenclature | Substitutive suffixes ‘nitrile’ for –(C)N and ‘carbonitrile’ for –CN; prefix ‘cyano’ when not the principal group; functional class name ‘cyanide’[6](https://iupac.qmul.ac.uk/BlueBook/P6a.html) |
| Signature reactions | Hydrolysis to amide then carboxylic acid; reduction with LiAlH₄ to a primary amine; Grignard addition followed by hydrolysis to a ketone[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles) |
| Preparation | Sᴺ2 reaction of CN⁻ with primary or secondary alkyl halides; dehydration of primary amides with SOCl₂ or POCl₃[7](https://ncstate.pressbooks.pub/organicchem/chapter/20-7-chemistry-of-nitriles/) |
| Acetonitrile | CAS 75-05-8; boiling point 179 °F; miscible with water; NIOSH REL 20 ppm TWA; IDLH 137 ppm; forms cyanide in the body[3](https://www.cdc.gov/niosh/npg/npgd0006.html) |
| Industrial role | Acrylonitrile is the monomer for acrylic fibers, ABS and SAN resins, adiponitrile, acrylamide, nitrile rubbers, and carbon fibers[4](https://pubchem.ncbi.nlm.nih.gov/compound/Akrylonitril) |
| Medicinal role | More than 30 nitrile-containing pharmaceuticals have been FDA approved; at least one every year since 2010, with five in 2020[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC8528211/) |
## Structure and polarity
The −C≡N unit is linear: the nitrogen atom is bonded to an sp-hybridized carbon through a triple bond[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9945868/). Like a carbonyl group, the nitrile group is strongly polarized, so its carbon atom is electrophilic and reacts with nucleophiles to give sp²-hybridized imine anions, in a step analogous to the formation of an sp³-hybridized alkoxide ion by addition to a carbonyl[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles). In systematic nomenclature the suffix ‘nitrile’ denotes the triply bound nitrogen atom, not the carbon attached to it[1](https://goldbook.iupac.org/terms/view/N04151/1000).
## Nomenclature
IUPAC rules give nitriles three naming routes[6](https://iupac.qmul.ac.uk/BlueBook/P6a.html):
1. Substitutive naming with the suffix ‘nitrile’ for –(C)N, as in hexanenitrile, or ‘carbonitrile’ for –CN attached to a ring, ring system, or acyclic heteroatom, as in cyclohexanecarbonitrile.
2. Changing the ‘ic acid’ or ‘oic acid’ ending of a retained carboxylic acid name into ‘onitrile’; acetonitrile, benzonitrile, and formonitrile are preferred IUPAC names of this kind, formonitrile being the preferred name for HCN.
3. Functional class naming with the class name ‘cyanide’, as in pentyl cyanide for hexanenitrile.
When a higher-priority group is present, or when the –CN group cannot be expressed as the principal characteristic group, the preferred prefix is ‘cyano’, as in 3-cyanopropanoic acid[6](https://iupac.qmul.ac.uk/BlueBook/P6a.html). In the seniority order of classes, nitriles rank senior to ketones, hydroxy compounds, amines, and imines, so those classes are cited as prefixes when a nitrile group is present[6](https://iupac.qmul.ac.uk/BlueBook/P6a.html). Functional isomers of the form R−NC, called isocyanides or isonitriles, are a separate class[9](https://pubs.acs.org/doi/pdf/10.1021/ba-1974-0126.ch031).
## Preparation
The simplest laboratory method is the Sᴺ2 reaction of the cyanide ion, CN⁻, with a primary or secondary alkyl halide, which extends the carbon chain by one carbon[7](https://ncstate.pressbooks.pub/organicchem/chapter/20-7-chemistry-of-nitriles/). The alternative is dehydration of a primary amide, RCONH₂, most often with thionyl chloride, though POCl₃ and other dehydrating agents also work; the amide synthesis is the more general of the two because it is not limited by steric hindrance at the reacting carbon[7](https://ncstate.pressbooks.pub/organicchem/chapter/20-7-chemistry-of-nitriles/).
## Reactions
**Hydrolysis.** Among the most useful reactions of nitriles is hydrolysis, which yields first an amide and then a carboxylic acid plus ammonia or an amine; the reaction proceeds in either acidic or basic aqueous solution[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles). In base, hydroxide adds to the polar C≡N bond to give an imine anion, protonation gives a hydroxy imine, and tautomerization produces the amide, in a step similar to the tautomerization of an enol to a ketone[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles). Further hydrolysis of the amide carbonyl, with expulsion of amide ion as the leaving group, gives the carboxylate, and a separate acidification step yields the carboxylic acid[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles). Both acid- and base-induced hydrolysis require rather severe conditions[10](https://thestemtutor.org/wp-content/uploads/2024/10/Organic-Chemistry-5e-by-Maitland-Jones-Jr.-Steven-A.-Fleming.pdf).
**Reduction.** Reduction with lithium aluminum hydride, LiAlH₄, gives a primary amine, RNH₂[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles). Hydride adds to the C≡N bond to form an imine anion, a second hydride addition gives a dianion, and protonation by water in the workup delivers the amine; both anionic intermediates are stabilized by Lewis acid–base complexation to aluminum species[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles).
**Grignard addition.** Grignard reagents add once to the nitrile carbon to give an imine anion, which water hydrolyzes to a ketone; the hydrolysis is the exact reverse of imine formation[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles). The reaction differs from reduction in that only one nucleophilic addition occurs and the attacking nucleophile is a carbanion rather than hydride[2](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles).
## Physical properties
Nitriles cannot hydrogen bond with themselves, but they can hydrogen bond with water through the lone pair on nitrogen, which explains their water solubility[11](https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_%28Organic_Chemistry%29/Nitriles/Properties_of_Nitriles/Physical_Properties_of_Nitriles). Ethanenitrile (acetonitrile) is completely miscible with water, and solubility falls as chain length increases: propanenitrile dissolves to 10 g per 100 cm³ of water and butanenitrile to 3 g per 100 cm³ at 20 °C[11](https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_%28Organic_Chemistry%29/Nitriles/Properties_of_Nitriles/Physical_Properties_of_Nitriles). Acetonitrile is a colorless liquid with an aromatic odor, boiling point 179 °F, freezing point −49 °F, and specific gravity 0.78[3](https://www.cdc.gov/niosh/npg/npgd0006.html).
## Industrial and medicinal uses
**Polymers.** [Acrylonitrile](https://www.edgepedia.org/acrylonitrile) (H₂C=CHCN) is used principally as a monomer in the manufacture of synthetic polymers. Its major end uses are acrylic fiber, acrylonitrile-butadiene-styrene (ABS) and styrene-acrylonitrile resins, adiponitrile, acrylamide, nitrile rubbers, and carbon fibers[4](https://pubchem.ncbi.nlm.nih.gov/compound/Akrylonitril). The cyano group also appears in cyanoacrylate adhesives, the basis of superglue[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9945868/).
**Pharmaceuticals.** The nitrile group is widely found in drugs and natural products. More than 30 nitrile-containing pharmaceuticals have been approved by the US FDA, and since 2010 at least one has been approved every year, reaching five in 2020[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC8528211/). One review counts over 70 approved drugs bearing the group, 61 of them small organic molecules[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9945868/). Medicinally the group serves mainly as a hydrogen bond acceptor, owing to the electronegativity of the nitrile nitrogen, and is regarded as a bioisostere (a replacement group mimicking another's shape and function in a drug) of carbonyl, hydroxyl, and halogen groups[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC8528211/). It is metabolically stable, and in most nitrile-containing drugs it passes through the body unchanged[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC8528211/) • [12](https://pmc.ncbi.nlm.nih.gov/articles/PMC2988972/). Incorporating a nitrile into a lead compound can enhance binding affinity, improve pharmacokinetics, and reduce drug resistance[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC8528211/).
## Toxicity
Toxicity depends strongly on the compound. Most organic nitriles are much less toxic than cyanide salts[13](https://www.chemistry-dictionary.com/nitrile/), but acetonitrile is an exception worth handling with care: NIOSH notes that it forms cyanide in the body, sets a recommended exposure limit of 20 ppm (34 mg/m³) as an 8-hour time-weighted average against an OSHA permissible exposure limit of 40 ppm, and lists an immediately dangerous to life or health concentration of 137 ppm[3](https://www.cdc.gov/niosh/npg/npgd0006.html). Acetonitrile is a Class IB flammable liquid with a flash point of 42 °F, explosive limits of 3.0 to 16.0 percent, and target organs including the respiratory and cardiovascular systems, the central nervous system, the liver, and the kidneys[3](https://www.cdc.gov/niosh/npg/npgd0006.html). In pharmaceuticals, release of toxic cyanide metabolites occurs only in rare cases such as mandelonitrile[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC8528211/).
## Nitriles in space
Nitrile chemistry is not confined to Earth. Surveys of protoplanetary disks find consistent relative abundances of CH₃CN, HC₃N, and HCN between disks, protostellar envelopes, and solar system comets, which suggests a robust nitrile chemistry operating under a wide range of physical conditions[14](https://arxiv.org/abs/1803.04986). Interstellar nitriles are proposed as key prebiotic molecules because of their chemical connection to the peptide bond after hydrolysis[15](https://arxiv.org/abs/2506.08792).
## References
1. [IUPAC Gold Book: nitriles (N04151)](https://goldbook.iupac.org/terms/view/N04151/1000)
2. [20.7 Chemistry of Nitriles, Organic Chemistry, OpenStax](https://openstax.org/books/organic-chemistry/pages/20-7-chemistry-of-nitriles)
3. [NIOSH Pocket Guide to Chemical Hazards: Acetonitrile, CDC](https://www.cdc.gov/niosh/npg/npgd0006.html)
4. [Acrylonitrile, PubChem, NCBI](https://pubchem.ncbi.nlm.nih.gov/compound/Akrylonitril)
5. [Nitriles: an attractive approach to the development of covalent inhibitors, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC9945868/)
6. [IUPAC Blue Book, P-66.5: Nitriles](https://iupac.qmul.ac.uk/BlueBook/P6a.html)
7. [20.7 Chemistry of Nitriles, Organic Chemistry: A Tenth Edition (OpenStax adaptation), NC State Pressbooks](https://ncstate.pressbooks.pub/organicchem/chapter/20-7-chemistry-of-nitriles/)
8. [Nitrile-containing pharmaceuticals: target, mechanism of action, and their SAR studies, RSC Med Chem via PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC8528211/)
9. [Nitriles, Nomenclature of Organic Compounds: Principles and Practice, ACS Advances in Chemistry](https://pubs.acs.org/doi/pdf/10.1021/ba-1974-0126.ch031)
10. [Organic Chemistry, Fifth Edition, Jones and Fleming](https://thestemtutor.org/wp-content/uploads/2024/10/Organic-Chemistry-5e-by-Maitland-Jones-Jr.-Steven-A.-Fleming.pdf)
11. [Physical Properties of Nitriles, Chemistry LibreTexts](https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_%28Organic_Chemistry%29/Nitriles/Properties_of_Nitriles/Physical_Properties_of_Nitriles)
12. [Nitrile-Containing Pharmaceuticals: Efficacious Roles of the Nitrile Pharmacophore, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC2988972/)
13. [Nitrile Definition in Organic Chemistry, Chemistry Dictionary](https://www.chemistry-dictionary.com/nitrile/)
14. [A Survey of CH3CN and HC3N in Protoplanetary Disks, arXiv](https://arxiv.org/abs/1803.04986)
15. [Interstellar Chemistry of CN Radicals on Ices, arXiv](https://arxiv.org/abs/2506.08792)
---
*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Organic substances › Amines and nitrogen functional groups › Nitriles, nitro, diazo, and related nitrogen groups › Nitriles, isocyanides, and cyano compounds*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license