What is Acetonitrile Definition Formula Preparation and Uses
Table of Content
It is a chemical compound with the formula C2H3N or CH3CN and it is a volatile organic compound. Acetonitrile is also called Cyanomethane or Methane Carbonitrile. It’s IUPAC name is Acetonitrile. It is a nitrile which is a hydrogen cyanide where the hydrogen (H) is replaced by a methyl group (-CH3). Acetonitrile is a limpid liquid, which is totally colourless. It has an aromatic odor. Compared with water it is less dense than water. When compared with air, it’s vapours are denser. Acetonitrile is easily soluble in water and it has a sweetish taste. It is used as a medium-polarity solvent in the laboratory. Acetonitrile was first prepared by Jean Baptiste Dumas in the year of 1847. It is mainly produced as a byproduct of acrylonitrile manufacture. In the European Economic Area since March 2000, acetonitrile has been banned in cosmetic products. It is often preferred as safe for domestic use.
Properties 0f Acetonitrile - C2H3N or CH3CN
Molecular weight: 41.05 g/mol
Density: 786 kg/m3
Melting point: -46oC to -44oC
Boiling point: 81.3oC to 82.1oC
IUPAC ID: Acetonitrile
Colour: Colorless
Odor: Aromatic odor
Taste: Sweetish taste
Solubility: Soluble in water
Chemical names: Methyl cyanide, Cyanomethane, Ethanenitrile
Structure Of Acetonitrile - C2H3N or CH3CN
Acetonitrile is classified as a nitrile in terms of its functional group. As per organic chemistry, a nitrile is defined as a carbon atom that contains a triple bond to a nitrogen atom. Acetonitrile is the simplest organic nitrile which contains a carbon nitrogen triple bond.
Preparation Of Acetonitrile - C2H3N or CH3CN
By manufacturing acrylonitrile, it is obtained as a byproduct. It can also be synthesized by hydrogenation of mixtures of carbon monoxide or dehydration of acetamide and ammonia. A method was disclosed with the invention for preparing high purity Acetonitrile from acetic acid and ammonia by two steps which consist of the following two steps, 1. neutralizing acetic acid and ammonia to generate ammonium acetate, 2. Mixing aqueous solution of ammonium acetate and gaseous ammonia, preheating and making the mixture enter a fixed bed reactor which is filled with a catalyst aluminium oxide for reaction to generate acetonitrile which containing mixed gas, after continuously refining the gas we got pure Acetonitrile.
Uses Of Acetonitrile (C2H3N)
In the extraction process of hydrocarbons, acetonitrile is used as a solvent.
For the chemical reactions and in chromatography chemists use it as a solvent.
To separate fatty acid from vegetable oil we use acetonitrile.
Acetonitrile is used in making perfumes.
In the production of synthetic pharmaceuticals, acetonitrile is widely used.
Acetonitrile is used in the manufacturing of rubber.
It is used in extraction of copper as well as refining.
In electrochemical cells, it is used as a solvent.
Because of its relatively high dielectric constant and ability to dissolve electrolytes, it is widely used in battery application.
Acetonitrile is being used in high-performance liquid chromatography (HPLC).
Acetonitrile has been used in formulations for nail polish remover
In the manufacturing of DNA oligonucleotides, in a pharmaceutical field and in photographic film, acetonitrile is used as a solvent.
Fun Facts
1. Acetonitrile is a liquid that is colorless.
2. In the group nitrile acetonitrile is the simplest molecule.
3. Acetonitrile is quite cheap because it is made when plastic is being made.
4. Acetonitrile must be handled with caution because it is an extremely dangerous product, it can cause severe health effects or death. Since acetonitrile is flammable, it can hurt our eyes.
5. Symptoms of acetonitrile exposure look like cyanide exposure and it can include pink colouring of the skin, dilated pupils, headache, nausea, and vomiting, dizziness, weakness, stiffness of the lower jaw, anxiety, pain and tightness in the chest, rapid breathing and pulse, irregular heartbeat, shortness of breath, etc.
6. Despite its toxicity, it has been used in formulations for nail polish remover. By acetonitrile-based nail polish remover, at least two cases have been reported of accidental poisoning of young children, one of which was fatal.
7. In the European Economic Area since March 2000, acetonitrile has been banned in cosmetic products. It is often preferred as safe for domestic use.
FAQs on Acetonitrile Structure Properties and Chemical Behavior
1. What is acetonitrile?
Acetonitrile is a polar organic compound with the chemical formula CH3CN and is the simplest nitrile. It consists of a methyl group (CH3–) attached to a nitrile group (–C≡N), making it a member of the nitrile functional group family. Acetonitrile is a colorless, volatile liquid widely used as a solvent in organic synthesis and analytical chemistry, especially in high-performance liquid chromatography (HPLC).
2. What is the chemical formula and structure of acetonitrile?
The chemical formula of acetonitrile is CH3CN, and its structural formula is CH3–C≡N. The molecule contains:
- A methyl group (CH3–)
- A carbon–nitrogen triple bond (C≡N) known as the nitrile group
The carbon in the –C≡N group is sp-hybridized, giving the molecule a linear arrangement at the nitrile end, which contributes to its polarity and solvent properties.
3. Is acetonitrile polar or nonpolar?
Acetonitrile is a polar aprotic solvent due to the strong dipole created by the C≡N bond. The electronegativity difference between carbon and nitrogen in the nitrile group produces a significant dipole moment. However, acetonitrile does not donate hydrogen bonds because it lacks O–H or N–H bonds, which is why it is classified as aprotic. This polarity makes it useful for dissolving many ionic and polar compounds.
4. What is the molar mass of acetonitrile?
The molar mass of acetonitrile (CH3CN) is 41.05 g·mol-1. It is calculated as follows:
- Carbon: 2 × 12.01 = 24.02 g·mol-1
- Hydrogen: 3 × 1.008 = 3.024 g·mol-1
- Nitrogen: 1 × 14.01 = 14.01 g·mol-1
Total = 24.02 + 3.024 + 14.01 ≈ 41.05 g·mol-1.
5. How is acetonitrile produced industrially?
Acetonitrile is mainly produced as a byproduct during the manufacture of acrylonitrile by the ammoxidation of propylene. The primary reaction is:
2CH3CH=CH2(g) + 2NH3(g) + 3O2(g) → 2CH2=CHCN(g) + 6H2O(g)
During this process, small amounts of CH3CN are formed as a side product and then separated and purified by distillation.
6. What are the main uses of acetonitrile in chemistry?
Acetonitrile is primarily used as a solvent in analytical and organic chemistry. Its main uses include:
- HPLC (High-Performance Liquid Chromatography) mobile phase
- Solvent in organic synthesis
- Electrolyte solvent in electrochemistry
- Extraction and purification of pharmaceuticals
Its low viscosity, high polarity, and relatively low boiling point make it ideal for laboratory and industrial applications.
7. What happens when acetonitrile is hydrolyzed?
When acetonitrile undergoes hydrolysis, it forms acetamide and eventually acetic acid under acidic or basic conditions. In acidic hydrolysis, the overall reaction is:
CH3CN + 2H2O + HCl → CH3COOH + NH4Cl
The nitrile group (–C≡N) is first converted into an amide (CH3CONH2), which then hydrolyzes further to a carboxylic acid.
8. Is acetonitrile acidic or basic?
Acetonitrile is generally considered neutral, but it is weakly acidic at the methyl hydrogen atoms. The hydrogen atoms on the CH3 group can be removed by very strong bases because the resulting carbanion is stabilized by the adjacent nitrile group. However, under normal laboratory conditions, acetonitrile behaves as a neutral polar aprotic solvent.
9. What is the boiling point of acetonitrile?
The boiling point of acetonitrile is approximately 81.6°C at 1 atm pressure. This relatively low boiling point is due to:
- Moderate intermolecular dipole–dipole interactions
- Absence of strong hydrogen bonding between molecules
Its volatility makes it easy to remove after reactions, which is useful in organic synthesis and analytical chemistry.
10. What is the difference between acetonitrile and acrylonitrile?
The main difference is that acetonitrile (CH3CN) is a saturated nitrile, while acrylonitrile (CH2=CHCN) contains a carbon–carbon double bond. Key differences include:
- Acetonitrile: Simple nitrile, used mainly as a solvent
- Acrylonitrile: Unsaturated nitrile, used to make polymers like polyacrylonitrile
Acrylonitrile is more reactive due to the C=C bond, whereas acetonitrile is relatively stable and widely used in analytical chemistry.
