Acetic acid, also known as glacial acetic acid or anhydrous acetic acid, is the purest form of acetic acid (vinegar acid). Because it solidifies into colorless crystals at a temperature slightly below room temperature, resembling ice blocks, it is named "glacial" acetic acid.

CAS Number: 64-19-7

Molecular formula: C₂H₄O₂ (commonly written as CH₃COOH)

Molecular weight: 60.05

EINECS Number: 200-580-7

It is one of the important organic acids and is the main source of the sour taste in vinegar (which contains approximately 3-5% of this acid). In industry, it is a basic chemical raw material; in laboratories, it is a commonly used solvent and analytical reagent.

Key parameters

Advantageous features

• High purity and strong acidity: The acetic acid in ice form has an extremely low moisture content and its concentration can reach over 98%. It is more acidic than ordinary dilute acetic acid solutions and has high reactivity.

• Freezing point characteristics: The melting point of 16.6℃ is its most notable physical property, which facilitates purification and separation through crystallization methods. However, in winter, it is necessary to pay attention to keeping it stored at a constant temperature to prevent it from freezing and bursting the container.

• Good miscibility: It can be infinitely miscible with water and most organic solvents (such as ethanol, ether), making it an excellent medium for organic reactions.

• Corrosiveness and Hygroscopicity: In the absence of water, it has hygroscopic properties and is corrosive to metals; it is irritating to the skin and can cause burns.

Purpose

The applications of acetic acid cover various fields such as chemical engineering, medicine, food, and household chemicals:

1. Large-scale chemical synthesis (primary application)

Synthetic fibers: Used for producing vinyl acetate (which is then used to make vinylon, adhesives), cellulose acetate (used in cigarette filters, textile fabrics, liquid crystal display polarizing films, etc.).

Plastics and bottle fragments: They are used to produce terephthalic acid, which is a key intermediate in the production of polyesters (such as PET for beverage bottles and polyester fabrics).

Ester solvents: React with alcohols to form ethyl acetate, butyl acetate, etc. These are important solvents used in the coatings, inks, and adhesives industries.

2. Medical field

Pharmaceutical raw material synthesis: Used for the synthesis of aspirin (acetylsalicylic acid), sulfonamide drugs, vitamins, etc.

Application of the preparation: In the topical preparations at specific concentrations, 5% acetic acid has a bactericidal effect, while 5% - 10% has a keratolytic effect. It is commonly used for treating tinea manuum (hand fungus), tinea pedis (foot fungus), and as an auxiliary treatment for onychomycosis (gray nail disease).

3. Food and Daily Necessities

Acidity regulator: As a food additive, it is used to adjust the pH value or as an acidulant, and is employed in some seasonings and beverages (E260).

Cosmetics products: Solvents used for manufacturing dyes, fixatives and additives for fabric printing.

4. Laboratory and Analysis

Analytical reagents: Used for preparing buffer solutions, adjusting acidity, and precipitating proteins in experimental operations.

Safety and Storage

• Hazardousness: It is corrosive and irritating. Contact with skin can cause burns; its vapor has a strong irritating effect on the eyes, nasal mucosa and respiratory tract. Flammable (flash point 39℃).

• Storage requirements: It must be stored in a sealed container in a cool, dry, and well-ventilated place. The environmental temperature should be maintained above 16.6℃ to prevent solidification and the resulting cracking of the glass container.

• Emergency handling: In case of accidental skin contact, immediately rinse with plenty of running water for at least 15 minutes and seek medical attention.