Acetic acid, glacial

• BPGlacial Acetic Acid
• JPGlacial Acetic Acid
• Ph. Eur.Acetic Acid, Glacial
• USP–NFGlacial Acetic Acid

Acetic acid; acidum aceticum glaciale; ethanoic acid; ethylic acid; methanecarboxylic acid; vinegar acid; E260

Ethanoic acid · [64-19-7]

UNII Q40Q9N063P · PubChem CID 176

C2H4O2 · 60.05

pH adjuster, buffering agent

Typical concentrations: — · Dosage forms: Liquid, Sterile (parenteral/ophthalmic)

Used mainly as an acidifying agent and, together with sodium acetate, as an acetate buffer (useful around pH 3.5–5.5) in injections, ophthalmic, nasal, otic, oral and topical preparations. Diluted acetic acid has antibacterial and antifungal activity and is used in some otic and irrigation solutions. It is also a food acidulant and flavouring.

A clear, colourless, volatile liquid with a pungent, characteristic vinegar-like odour. Glacial acetic acid contains about 99–100% w/w of C2H4O2 and crystallises when cooled slightly below room temperature.

Boiling point

≈ 118 °C

Melting point

≈ 16.6 °C (solidifies in a cool room, hence 'glacial')

Density

≈ 1.05 g/cm³ at 20 °C

pKa

4.76 (25 °C)

Flash point

≈ 39 °C (closed cup)

Solubility

miscible with water, ethanol, glycerol and ether

Stable. Store in an airtight container in a cool place, away from sources of ignition and from materials with which it reacts.

Reacts with alkaline substances and carbonates. It can react vigorously or explosively with strong oxidising agents such as chromium trioxide, nitric acid, perchloric acid, peroxides and permanganates, and it attacks many metals.

Most acetic acid is made by carbonylation of methanol with carbon monoxide over a rhodium or iridium catalyst; older routes include oxidation of acetaldehyde or of hydrocarbons. Vinegar (dilute acetic acid) is produced by bacterial oxidation of ethanol.

Dilute solutions, as used in food and medicines, are well tolerated, and JECFA has not limited the acceptable daily intake. The concentrated acid is corrosive: it burns the skin, eyes and mucous membranes, and swallowing it can cause severe oesophageal and gastric injury. The vapour irritates the respiratory tract.

Handle the concentrated acid in a fume cupboard or well-ventilated area, wearing gloves, eye protection or a face shield and protective clothing. It is flammable; keep away from heat and flames. Splashes should be washed off with plenty of water.

GRAS listed. Accepted as a food additive in Europe (E260). Classified as an ICH Q3C Class 3 residual solvent. Included in the FDA Inactive Ingredient Database (injections, nasal, ophthalmic, otic, oral and topical preparations) and in parenteral and non-parenteral medicines licensed in Europe.

Acetic acid (diluted grades, for example USP–NF Acetic Acid containing 36–37% w/w); sodium acetate; potassium acetate.

Diluted grades are much more convenient for pH adjustment in formulation work. Glacial acetic acid may solidify in a cold store; gently warming the container restores it to liquid without affecting quality.