Acetonitrile

Acetonitrile (CAS 75-05-8), also known as methyl cyanide, cyanomethane, or ACN, is a high-purity polar aprotic solvent widely used in analytical chemistry, pharmaceutical manufacturing, and organic synthesis. With the molecular formula CH₃CN and molecular weight 41.05 g/mol, this colorless, volatile liquid offers excellent solvating power for a broad range of polar and non-polar compounds.

Key Physical and Chemical Properties

• Appearance: Clear, colorless liquid

• Purity: Typically ≥99.9% (HPLC/GC grade available)

• Boiling Point: 81–82 °C

• Melting Point: -46 °C to -44 °C

• Density: 0.786 g/mL at 25 °C

• Flash Point: 2 °C (highly flammable)

• Vapor Pressure: ~73 mmHg at 20 °C

• Refractive Index: n20/D 1.344

• Water Miscibility: Completely miscible

• Odor: Mild ether-like (detection threshold ~40 ppm)

Acetonitrile stands out for its low viscosity, high dielectric constant, and UV transparency (low absorbance at 190–230 nm in high-purity grades), making it ideal for demanding applications.

Primary Applications and Uses

• HPLC and LC-MS Mobile Phase: Preferred eluent in reversed-phase high-performance liquid chromatography due to low viscosity, excellent peak shape, and low UV cutoff (~190 nm).

  
  

• Pharmaceutical Synthesis and Purification: Used as a reaction solvent, extraction medium, and crystallization solvent in API manufacturing and peptide synthesis.

  
  

• Organic Chemistry: Polar aprotic solvent for nucleophilic reactions, Grignard reagents, and extraction of oils, hydrocarbons, and natural products.

  
  

• Analytical Chemistry: Dissolves salts, polar organics, and supports spectroscopy, electrochemistry, and battery research.

  
  

• Industrial Processes: Butadiene extraction, specialty chemical production, and as a starting material for certain intermediates.

  
  

Why Choose Our High-Purity Acetonitrile?

Our acetonitrile meets or exceeds ACS, USP/NF, and Ph. Eur. reagent specifications, with strict control over impurities such as water (≤0.01% in ultra-dry grades), acidity, and UV-absorbing contaminants. Packaged under inert gas to maintain quality, it ensures reproducible results in sensitive gradient HPLC, UHPLC, and moisture-sensitive syntheses. Available in various grades: HPLC gradient grade, LC-MS grade, anhydrous, and ultra-high purity.

Safety and Handling Information

Acetonitrile is classified as a flammable liquid (Category 2) with acute toxicity via inhalation, skin absorption, and ingestion. Handle in well-ventilated areas with proper PPE (gloves, goggles, flame-resistant clothing). Store in tightly sealed containers under inert gas, away from ignition sources, at +5 °C to +30 °C. Refer to the latest SDS for complete hazard and disposal guidelines.

Frequently Asked Questions (FAQs)

What is the CAS number for acetonitrile?

The CAS number is 75-05-8.

Is acetonitrile the same as methyl cyanide?

Yes, acetonitrile (CH₃CN) is commonly called methyl cyanide or ethanenitrile.

Why is acetonitrile preferred over methanol in HPLC?

Acetonitrile provides lower viscosity, better peak resolution, shorter run times, and lower backpressure in reversed-phase systems.

What grade of acetonitrile is best for LC-MS?

LC-MS grade or ultra-high purity acetonitrile with minimal metal ions, water, and organic impurities is recommended to reduce background noise and ion suppression.

How should acetonitrile be stored?

Store in a cool, dry place in tightly closed containers under inert atmosphere to prevent moisture absorption and degradation.

Is acetonitrile fully miscible with water?

Yes, acetonitrile is completely miscible with water and most organic solvents.

For quotations, technical data sheets, samples, or bulk orders of acetonitrile CAS 75-05-8, please reach out to our team.

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