CBSE Class 12 chemistry practical, Organic preparation · Preparation of compounds
Source: CBSE Class 12 chemistry practical syllabus · use your school laboratory manual (NCERT Lab Manual where your school uses it).
Preparation of acetanilide (Class 12 chemistry practical)
You react aniline with acetic anhydride in aqueous or glacial conditions as your manual describes.
Record melting point range only if your school measures it — do not invent °C values on this sheet.
Published practice page. Concentrations, masses, and numerical answers come from your school laboratory manual and your own readings — not invented here. Not yet reviewed by a named chemistry reviewer. Version 1.0.0, updated 2026-10-03.
Safety — read before you start
Safety warning. Practise here. Perform the real experiment only in your school lab, with your teacher present.
- Aniline toxic.
- Acetic anhydride corrosive and lachrymatory.
- Flammable vapours.
Wear: Lab coat, Splash goggles, Gloves, as your teacher directs.
Follow your teacher’s disposal instructions. Do not pour leftovers down a household drain.
Loads only after you tap. Use the lab hands to pick up and use equipment (pointer hidden in the scene). Falls back to a flat diagram if WebGL is unavailable.
Aim
To prepare acetanilide by acetylation of aniline and purify the product by crystallisation as directed in your laboratory manual.
Methods and quantities can differ between schools. Follow your teacher's instructions.
Apparatus and chemicals
| Item | Note |
|---|---|
| Conical flask | For reaction. |
| Glass rod | Stirring. |
| Funnel and filter paper | Collect crystals. |
| Beaker for recrystallisation | Hot water or ethanol as manual. |
| Balance | Weigh aniline and product. |
| Aniline (C6H5NH2) | Toxic — use only in ventilated lab. |
| Acetic anhydride ((CH3CO)2O) | Use the concentration, mass, and volume values printed in your school laboratory manual. This page does not invent a numerical result for you. |
| Glacial acetic acid (if manual) (CH3COOH) | Catalyst or solvent as directed. |
| Water / ethanol (H2O EtOH) | For hydrolysis excess anhydride and recrystallisation. |
Theory and reaction
Open
Nucleophilic acetylation: aniline attacks acetic anhydride to give acetanilide and acetic acid.
Acetanilide is less basic than aniline because the lone pair on nitrogen is delocalised into the carbonyl.
Purification uses difference in solubility — hot solvent, cool slowly.
Aniline plus acetic anhydride gives acetanilide and acetic acid.
Procedure
- Measure aniline and acetic anhydride as manual states. Mix in flask with acetic acid if required.Safety: Aniline toxic by skin absorption; acetic anhydride lachrymatory — goggles and ventilation.
- Warm gently if manual asks until reaction completes.
- Pour into cold water to destroy excess anhydride and precipitate acetanilide.
- Filter, recrystallise from hot water or ethanol as directed, dry and weigh.
- Note crystal shape and colour (should be colourless flakes if pure).
Observation table
Enter the readings from your school lab in the practical file below. This page does not fill them in for you.
Calculation
Theoretical yield from aniline as limiting reagent. Percentage yield = actual/theoretical × 100.
Result
Report mass of acetanilide and percentage yield; melting point if your class measured it.
Precautions
- No flames near aniline vapour — flammable and toxic.
- Work in fume hood if available.
- Do not pour organic residues down sink.
Viva questions
Answer one question at a time. The full answers stay closed until you open them.
Question 1 of 4
Acetanilide is formed by…
Pick an answer first.
Show all questions and answers
Acetanilide is formed by…
Answer: Acetylation of aniline. Reason: Acyl group transfers from acetic anhydride to nitrogen.
Aniline is acetylated to…
Answer: Reduce basicity / protect −NH₂ in synthesis. Reason: Acetylation caps the amine, lowering basicity.
Excess acetic anhydride is destroyed by…
Answer: Pouring into water (hydrolysis). Reason: Anhydride hydrolyses in water to acetic acid.
Recrystallisation purifies by…
Answer: Using solubility difference hot vs cold. Reason: Impurities stay in mother liquor or separate on cooling.
Common mistakes
- Skipping recrystallisation and reporting oily product.
- Using excess water that dissolves too much product.
- Confusing acetanilide with aniline by smell in report (minimise exposure).
Frequently asked questions
- Can I do this at home?
- No. Use this page to practise the order of steps and viva. Do the real experiment only in your school laboratory, with your teacher present.
Your practical file
Name, school, and roll number are optional and are not sent anywhere.
The practical file opens on this device.
Review
Not yet reviewed by a named chemistry reviewer. Published for practice only — follow your teacher and laboratory manual for quantities and safety.
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