Acetonitrile (MeCN): Properties, Production, Uses, and Safety

Physical and chemical characteristics

Acetonitrile is a polar, aprotic solvent. As a nitrile it contains a carbon–nitrogen triple bond, which gives it distinct reactivity compared with ketones or ethers. It dissolves a wide range of organic and inorganic compounds and often stabilizes reaction intermediates in organic synthesis. It is less nucleophilic than many oxygen-containing solvents and is therefore chosen when reduced interference with reagents is needed.

Production and history

Industrial acetonitrile is produced mainly as a byproduct of acrylonitrile manufacture and can also be prepared by dehydration of acetamide. Its availability increased with the growth of synthetic organic chemistry and polymer production in the 20th century, which made it relatively inexpensive and widely accessible for both analytical and preparative uses. For basic chemical data and references see chemical data.

Major uses and applications

Acetonitrile has several important roles:

• Chromatography: widely used as a solvent component in high-performance liquid chromatography (HPLC) mobile phases because it provides good peak shapes and low viscosity.
• Laboratory solvent: used in organic synthesis, extraction, and as a reaction medium where polar aprotic conditions are advantageous. Related analytical uses are described at analytical methods.
• Instrumentation and specialty: used in mass spectrometry and as a solvent for nuclear magnetic resonance when deuterated (e.g., CD3CN). It also appears in some battery electrolyte research and industrial processes; see industrial contexts for details.
• Research reagent and intermediate: serves in syntheses and as a precursor in more complex chemical manufacturing; overview resources: nitrile chemistry.

Safety, handling, and environmental notes

Acetonitrile is flammable and its vapors can form explosive mixtures with air. It is an irritant and can be toxic if inhaled, ingested, or absorbed through the skin. In biological systems it may be metabolized to cyanide, so exposure can produce delayed and serious effects; medical attention is required for significant exposures. Store it in a cool, well‑ventilated area away from ignition sources and follow applicable safety data sheet guidance (safety data). Environmental release should be minimized and managed according to local regulations; consult environmental guidance and industrial safety publications (analytical safety).