Introduction

Acetic acid (CH₃COOH), also known as ethanoic acid, is one of the most widely used and important carboxylic acids. “Glacial acetic acid” is a name for water-free (anhydrous) acetic acid. Its unique chemical properties make it a subject of interest in scientific, industrial and everyday applications.

In industry, acetic acid plays a significant role, being used in manufacturing processes and products ranging from food additives to pharmaceuticals, plastics, etc. Due to its acidity and oxidizing properties, acetic acid also finds application in the chemical industry for synthesizing various organic compounds.

In everyday life, acetic acid is widely used in the food industry, in the process of canning vegetables, making condiments and sauces. It is also a key component of some household and cosmetic products.

The purpose of this article is to review the physical and chemical properties of acetic acid, how it is produced and its various applications.

Physical and Chemical Properties of Acetic Acid

Acetic acid has the chemical formula CH₃COOH. It is a colorless liquid with a strong characteristic odor. It is liquid at room temperature. Acetic acid has a boiling point of 118 °C and a melting point of 16.6 °C. The molecular weight of acetic acid is approximately 60 g/mol. This acid is a weak organic acid and dissociates into ions when dissolved in water. Above 39°C explosive vapor/air mixtures may be formed. Auto-ignition temperature: 427°C.

How to make Glacial Acetic Acid

Synthesis of Acetic Acid

Methods of acetic acid production can include several methods, depending on the starting materials. Here are the main methods of acetic acid production.

The method of producing acetic acid from acetaldehyde involves the oxidation of acetaldehyde to acetic acid. This method of acetic acid production is widely used in industrial plants and produces high quality acid. Oxidation can be carried out using catalysts such as potassium permanganate (KMnO4).

The method of producing acetic acid from methanol with carbon dioxide is called catalytic carbonylation of methanol. This process involves the use of a special catalyst such as rhodium (Rh). Methanol and carbon monoxide are fed into a reaction chamber with a catalyst, under pressure and at high temperature.

Fermentation is one of the ways to produce acetic acid. In this process, alcoholic solutions are fermented by microorganisms. The microorganisms oxidize the ethyl alcohol, in the water alcoholic solution into acetic acid. The fermentation process takes place in special containers called acetic chambers, which provide sufficient oxygen for the microorganisms. Fermentation can be carried out at the industrial level and at home. It is a complex process that is described by a formal equation.

In the laboratory, acetic acid can be obtained by reacting sulfuric acid and sodium acetate. The by-product in this reaction is sodium hydrogen sulfate.

Each of these methods of acetic acid production has its own advantages and can be chosen depending on the production requirements and availability of raw materials.

Chemical Properties and Reactions of Acetic Acid

The chemical properties and reactions of acetic acid are used in a wide range of chemical processes. Here are some of the major reactions of acetic acid:

Acetic acid can react with various alcohols to form esters in a reaction known as esterification. Acetic acid reacts with an alcohol in the presence of an acid catalyst (usually sulfate sulfuric acid or phosphoric acid) to form an ester and a water molecule. This reaction is reversible.

Anhydrous acetic acid is a flammable substance, its vapors easily ignite. Burning of acetic acid produces carbon dioxide and water.

Acetic acid can react with alkalis to form acetate salts and water. The reaction between acetic acid and an alkali is called a neutralization reaction. The reaction is exothermic.

Acetic acid can react with active metals to form acetate salts and release hydrogen. Copper and iron do not react with acetic acid under normal conditions.

The chemical properties and reactions of acetic acid provide it with a wide range of applications in various chemical processes and reactions.

Acetic Acid Applications

Acetic acid has a wide range of applications in various industries. Here are some of the major applications of acetic acid:

• 1. Chemical industry: Acetic acid is an important raw material for synthesizing various organic compounds. It is used in the process of producing solvents, dyes and many other chemicals. Acetic acid is also used in the esterification process to produce esters.
• 2. Pharmaceutical industry: Acetic acid is used in the manufacture of various pharmaceuticals and medical products. It can be used as an acidity regulator and a component for creating drug formulas.
• 3. Food processing: Acetic acid is widely used in the production of food additives and preservatives. It is used in the preparation of various sauces, marinades and mayonnaise.
• 4. Household and cosmetic products: Acetic acid finds use in the manufacture of household and cosmetic products such as cleaning products, shampoos, conditioners and health products. In households, it can be used for descaling and cleaning surfaces. In the cosmetic industry, acetic acid can be added to hair and skin products to balance pH.

Health Effects of Acetic Acid

Acetic acid, when used properly and in small amounts, is generally considered safe for human health. However, with prolonged or improper use, acetic acid can have negative health effects. Here are some aspects of the health effects of acetic acid:

1. Irritation of skin and mucous membranes: Contact with concentrated acetic acid may cause skin irritation, redness and burns.
2. Tooth enamel damage: Acetic acid has a low pH and can damage tooth enamel with prolonged use. This can lead to the development of caries.
3. Interaction with certain drugs: Acetic acid may interact with certain medications, especially those containing acetaminophen or aspirin. This may affect the efficacy or safety of the medicines.
4. Digestive disorders: Ingestion of large doses of acetic acid may cause digestive upsets such as heartburn, nausea or stomach pain.

Safety Precautions

When working with acetic acid, certain safety precautions must be followed to prevent possible health risks. Here are some recommendations for safe handling of acetic acid:

Personal protective equipment such as protective clothing, goggles, masks and gloves must be worn when handling acid. Work with acid must be carried out under a fume hood – toxic fumes must be quickly removed. If acid solution comes into contact with skin, rinse with water immediately. In case of contact with eyes, rinse with plenty of water. Spilled acetic acid can be removed with water and an alkaline solution.

For the safe storage of acetic acid, special containers made of non-aggressive materials, such as glass containers, should be used. These materials should not be exposed to acetic acid.

Storage of acetic acid should be carried out in rooms with good ventilation. It is important to avoid contact with substances, that can react with acetic acid.

Conclusion

Acetic acid is an important chemical compound, that has a wide range of applications in various industries and in everyday life. Its physical and chemical properties make it a valuable raw material for the synthesis of various organic compounds. It finds applications in the food industry, chemical industry, pharmaceutical, household and cosmetic industries. Acetic acid is a corrosive substance and requires safety precautions when working with it.

Bibliography

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• Acetic Acid Frank S. Wagner Kirk-Othmer Encyclopedia of Chemical Technology 07.07.2014 https://doi.org/10.1002/0471238961.0103052023010714.a01.pub3
• Acetic Acid and its Derivatives Victor H. Agreda 456 pages 1992 https://books.google.com/books?id=t0dZDwAAQBAJ&dq
• Acetic Acid Bacteria in Winemaking: A Review G. S. Drysdale, G. H. Fleet Am J Enol Vitic. January 1988 39: 143-154 https://doi.org/10.5344/ajev.1988.39.2.143
• Acetic Acid Production and Purification: Critical Review Towards Process Intensification Parimal Pal & Jayato Nayak Pages 44-61 02.01.2016 https://doi.org/10.1080/15422119.2016.1185017