Aspirin is obtained by acetylation of
Aspirin is obtained by acetylation of
Options
Official answer
Correct option: (C) — 2-Hydroxybenzoic acid (salicylic acid).
Key idea: Aspirin is acetylsalicylic acid. It is made by acetylating the phenolic –OH of salicylic acid with acetic anhydride (or acetyl chloride):
- Salicylic acid (2-hydroxybenzoic acid) + (CH₃CO)₂O → Aspirin (acetylsalicylic acid) + CH₃COOH.
Marking scheme
- 1.1 mark: correctly selecting option (C) 2-Hydroxybenzoic acid.
- 2.Accepted reason: aspirin is acetylsalicylic acid, formed by acetylation of the phenolic –OH of salicylic acid.
Hint
Aspirin = acetylsalicylic acid; acetylate the –OH of salicylic acid, which is 2-hydroxybenzoic acid.
Quick oral answer
Aspirin is acetylsalicylic acid, obtained by acetylating the phenolic hydroxyl group of salicylic acid — that is, 2-hydroxybenzoic acid — using acetic anhydride.
Common mistakes
- 1.Choosing phenol or benzoic acid, missing that aspirin needs both a –COOH and an acetylated phenolic –OH.
- 2.Not recognising that 2-hydroxybenzoic acid is just the IUPAC name for salicylic acid.
- 3.Confusing salicylaldehyde (–CHO) with salicylic acid (–COOH).
Analysis and explanation
Concept:
Aspirin (acetylsalicylic acid) is a well-known analgesic and antipyretic. Its synthesis replaces the hydrogen of the phenolic –OH group in salicylic acid with an acetyl group (CH₃CO–), i.e. acetylation. The reagent is acetic anhydride (with a trace of acid catalyst).
Why the distractors are wrong:
- (A) Phenol has only an –OH but lacks the –COOH group; acetylating phenol gives phenyl acetate, not aspirin.
- (B) Salicylaldehyde (2-hydroxybenzaldehyde) has a –CHO, not the –COOH of aspirin; it cannot give acetylsalicylic acid.
- (D) Benzoic acid has a –COOH but no phenolic –OH to acetylate, so no aspirin forms.
- (C) 2-Hydroxybenzoic acid (salicylic acid) has both the –COOH (retained) and the phenolic –OH (acetylated), giving aspirin. ✅
Exam trap: 'Salicylic acid' and '2-hydroxybenzoic acid' are the same compound — recognise the IUPAC name.
Interesting facts
Aspirin was first marketed by Bayer in 1899; the name comes from 'a' (acetyl) + 'spir' (Spiraea, the meadowsweet plant that is a natural source of salicylates).
Low-dose aspirin is widely prescribed today as an antiplatelet agent to reduce the risk of heart attacks and strokes, beyond its original use as a painkiller.
Question details
Q6 of 37 questions
- Board
- CBSE
- Class
- Class 12
- Subject
- Chemistry
- Year
- 2026
- Section
- Section A
- Marks
- 1
- Type
- MCQ
- Chapter
- Chemistry in Everyday Life
- Topic
- Preparation of aspirin by acetylation
- Bloom's level
- remember
- Syllabus topic
- Unit: Chemistry in Everyday Life — Drugs (Analgesics/Antipyretics): Preparation of Aspirin by Acetylation of Salicylic Acid
- Author
- CBSE
- Reviewed by
- Padhantu Academic Team
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Frequently asked questions
What is the chemical name of aspirin and how is it prepared?
Aspirin is chemically acetylsalicylic acid. It is prepared by acetylating the phenolic –OH group of salicylic acid (2-hydroxybenzoic acid) with acetic anhydride in the presence of a trace of acid catalyst, which replaces the –OH hydrogen with an acetyl (CH₃CO–) group and releases acetic acid.
Why can't aspirin be made from phenol or benzoic acid?
Aspirin's structure needs both a carboxylic acid group and an acetylated phenolic oxygen on the same benzene ring. Phenol has an –OH but no –COOH, and benzoic acid has a –COOH but no phenolic –OH. Only salicylic acid (2-hydroxybenzoic acid) carries both groups, so it is the correct starting material.