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Parvez Ahmed Chowdhury: Synthesizing Aspirin in the Organic Chemistry Lab

Parvez Ahmed Chowdhury/LinkedIn

Sep 29, 2026, 03:21

Parvez Ahmed Chowdhury: Synthesizing Aspirin in the Organic Chemistry Lab

Parvez Ahmed Chowdhury, Treasurer at GSTU Research and Higher Studies Society, shared a post on LinkedIn:

“Synthesized aspirin in the lab today

Today I completed an Experiment in my organic chemistry lab: preparing acetylsalicylic acid (aspirin) from salicylic acid.

The reaction: Salicylic acid is acetylated by acetic anhydride, with concentrated H₂SO₄ as the catalyst. The phenolic OH attacks the protonated anhydride’s carbonyl carbon, then acetic acid is eliminated to give aspirin.

Procedure:

Mixed 5.0 g dry salicylic acid with 7.5 g (7.0 mL) acetic anhydride in a 100 mL conical flask
Added 2 to 3 drops of conc. H₂SO₄ and swirled to mix
Warmed on a water bath at 50 to 60 degree C for about 15 minutes
Cooled, then added 75 mL water to quench the excess anhydride and precipitate the crude aspirin
Filtered through a Büchner funnel under reduced pressure
Recrystallized from 15 mL hot ethanol poured into about 40 mL warm water
Dried the needle like crystals, then calculated percent yield.

Result: Yield: 91.6 percent

Aspirin is poorly soluble in water, which is why adding water both destroys the leftover anhydride and precipitates the product.

Recrystallization is what turns a crude solid into pure needle like crystals.

Seeing a textbook mechanism turn into real crystals in the flask is the best part of chemistry.” Parvez Ahmed Chowdhury: Synthesizing Aspirin in the Organic Chemistry Lab