Problem 21 - A Complete Resource Book in Chemistry for JEE Main

Question

Aspirin is an acetylation product of (a) o-hydroxybenzoic acid (b) \(\mathrm{p}\)-dihydroxybenzene (c) o-dihydroxybenzene (d) m-hydroxybenzoic acid

Step-by-Step Solution

Answer

Aspirin is an acetylation product of o-hydroxybenzoic acid (option a).

Step 1: Understand the Structure of Aspirin

Aspirin, also known as acetylsalicylic acid, is a member of the salicylate family. It is made by the acetylation of salicylic acid.

Step 2: Identify Salicylic Acid

Salicylic acid is also known as o-hydroxybenzoic acid because it has a hydroxyl group (OH) at the ortho position relative to the carboxyl group (COOH) on the benzene ring.

Step 3: Match Salicylic Acid with Options

In the given options, identify which compound corresponds to salicylic acid. The option (a) 'o-hydroxybenzoic acid' directly refers to salicylic acid.

Step 4: Conclusion

Since aspirin is formed by acetylating salicylic acid, which is also known as o-hydroxybenzoic acid, the answer to the exercise is (a).

Key Concepts

Acetylation

Acetylation is a chemical reaction in which an acetyl group is introduced into a compound. It is an important process in organic chemistry, frequently used to modify pharmaceuticals.
The main purpose of acetylation is to change the chemical property of a compound, often to improve its efficacy or to reduce its toxicity.

• In aspirin synthesis, acetylation involves the reaction of salicylic acid with acetic anhydride.
• During this reaction, the hydroxyl group (OH) of salicylic acid is replaced by an acetyl group (CH₃CO).
• This process results in the formation of acetylsalicylic acid, commonly known as aspirin.

Understanding acetylation is crucial for students studying chemical reactions, as it explains how minor chemical modifications can have a significant impact on a compound's application in medicine.

Salicylic acid

Salicylic acid is a key compound in both plant and human biochemistry. Known chemically as o-hydroxybenzoic acid, it has a hydroxyl group (-OH) attached to a benzene ring, positioned next to a carboxylic acid group (-COOH).
This particular arrangement of molecules gives salicylic acid unique properties, making it useful in various applications:

• Salicylic acid is a precursor to many pharmaceuticals, including aspirin.
• Thanks to its exfoliating properties, it's widely used in skincare to treat acne and remove dead skin cells.
• In plants, salicylic acid acts as a hormone that can influence growth and responses to stress.

Recognizing the structure and function of salicylic acid helps in understanding its role in both natural and synthetic contexts.

o-Hydroxybenzoic acid

o-Hydroxybenzoic acid is merely another name for salicylic acid, as discussed previously. The "o" in o-hydroxybenzoic acid stands for "ortho," indicating that the hydroxyl group is located adjacent to the carboxyl group on the benzene ring.
This specific configuration is crucial in determining the chemical properties and reactivity of the compound.
Such naming might appear complex, but once broken down, it simply describes the geometric position of the functional groups on the benzene ring.

• The ortho position affects the melting point and solubility of salicylic acid, impacting its use in different formulations.
• Understanding these terms can help students make sense of how chemical structure affects function.

Mastering these concepts will enhance one's ability to comprehend chemistry-related nomenclature and reactions.