Glacial acetic acid (GAA), CAS number 64-19-7, is the anhydrous or near-anhydrous form of acetic acid. It is a clear, colorless liquid with a sharp, irritating odor and strong corrosive properties. Because it is soluble in water and miscible with many organic solvents, glacial acetic acid plays a central role in chemical reactions, dissolution processes, and industrial manufacturing. This guide examines its properties, specifications, and the important question of whether glacial acetic acid is toxic.
Physicochemical Properties of Glacial Acetic Acid
Glacial acetic acid is distinguished by its ability to act as both a solvent and a reactive acid. Its high polarity allows it to dissolve a wide range of organic and inorganic substances, including many materials that are poorly soluble in water. It has a moderate volatility, which means it can be removed from reaction systems without contaminating products, yet it does not evaporate so quickly that it creates operational difficulties. Compared with many toxic and hazardous solvents, glacial acetic acid has relatively low systemic toxicity and better biodegradability, which supports its use in environmentally conscious manufacturing.
| Property | Value |
|---|---|
| Fusing point | 16.6 C |
| Boiling point | 117.9 C |
| Density | 1.05 g/cm3 |
| Flash point | 39 C (closed cup) |
| Refractive index | 1.371 at 20 C |
| Saturated vapor pressure | 1.52 kPa at 20 C |
| Critical temperature | 321.6 C |
| Critical pressure | 5.78 MPa |
| Auto-ignition temperature | 426 C |
| Explosion limits in air | 5.4% to 16.0% by volume |
Is Glacial Acetic Acid Toxic?
The answer depends on concentration and route of exposure. At the low concentrations found in vinegar and other food products, acetic acid is harmless for normal consumption. At the high concentrations encountered in laboratories and factories, however, glacial acetic acid is a strong irritant to the eyes, skin, and mucous membranes. Prolonged or repeated skin contact with concentrated acetic acid can cause tissue destruction and chemical burns, while inhalation of its vapors can irritate the respiratory tract. Ingestion of concentrated glacial acetic acid is a medical emergency and can cause serious internal injury. These hazards are reflected in classification systems that designate concentrated acetic acid as a corrosive substance, and occupational exposure limits apply in workplace settings.
Advantages of Glacial Acetic Acid as an Industrial Solvent
Glacial acetic acid offers several practical advantages in industrial applications. Its good solvency enables the preparation of coatings, inks, adhesives, and many other formulated products. Its moderate volatility supports clean removal from reaction mixtures, reducing the risk of product contamination. Its comparatively lower toxicity and better biodegradability make it a more environmentally favorable option than many traditional chlorinated or aromatic solvents. These properties explain why glacial acetic acid remains a staple solvent in chemical manufacturing, textile processing, and laboratory work.
Safe Handling and Storage Practices
Because glacial acetic acid is corrosive and flammable, safe handling requires appropriate controls. Always work in a well-ventilated area or under a fume hood, and wear chemical-resistant gloves, safety goggles, and protective clothing. Keep containers tightly closed and store the acid away from oxidizers, strong bases, and ignition sources. Since its flash point is 39 C, avoid open flames and hot surfaces near open containers. In case of skin or eye contact, flush the affected area with plenty of water and seek medical attention, and follow the guidance in the safety data sheet for spill containment and first aid.
Specifications for Industrial and Laboratory Use
Glacial acetic acid is available in grades that meet industrial and laboratory requirements. Key specification parameters include purity, fusing point, boiling point, density, and water content. Buyers should request a certificate of analysis and verify that the delivered grade matches the application, whether for synthesis, extraction, pH adjustment, or polymer processing. Standards such as GB/T and ISO guidance for acetic acid can be referenced for quality acceptance, and compliance with relevant transport and hazardous chemical regulations should be confirmed before shipment.
Frequently Asked Questions
Is glacial acetic acid the same as regular vinegar?
No. Vinegar is a dilute aqueous solution containing roughly 4 to 8 percent acetic acid, while glacial acetic acid is essentially pure acetic acid containing only trace amounts of water, making it far more corrosive and hazardous.
What should I do if glacial acetic acid touches my skin?
Immediately remove contaminated clothing and rinse the affected skin with large amounts of running water for at least 15 minutes, then seek medical attention, as concentrated acetic acid can cause chemical burns.
Can glacial acetic acid vapors cause health problems?
Yes. Inhalation of concentrated acetic acid vapors can irritate the nose, throat, and lungs, and high vapor concentrations may cause coughing, chest discomfort, and in severe cases, pulmonary irritation.
Why is glacial acetic acid called glacial?
The term glacial refers to the fact that pure acetic acid solidifies into ice-like crystals at approximately 16.6 C, well above typical room temperature in cool environments.
Is glacial acetic acid flammable?
Glacial acetic acid is a combustible liquid with a flash point of 39 C in a closed cup, so it can ignite when exposed to an ignition source, and its vapors form explosive mixtures with air between about 5.4% and 16.0% by volume.
What grades of glacial acetic acid are commonly supplied?
Glacial acetic acid is commonly supplied in industrial, food, and laboratory grades with different purity and impurity specifications; food grade meets additive standards, while laboratory grade is suited to analytical and synthesis work.
