An organic compound (A) with molecular formula C₆H₆O gives a characteristic colour with aqueous solution. When (A) is treated with CO₂ and NaOH at 410K under pressure, it gives compound (B) which upon acidification gives compound (C). Compound (C) reacts with acetyl chloride to give (D) which is a popular pain killer.  

Identify the product (D)?

Aspirin 

(i) Since, compound (A) with molecular formula C₆H₆O gives characteristic colour with FeCl₃, therefore (A) must be a phenol.
(ii) Since compound (A), i.e., phenol reacts with CO₂ and NaOH under pressure (i.e., Kolbe's reaction) to give compound (B) which on acidification gives compound (C), therefore, (B) must be sodium salicylate and (C) must be salicylic acid.
(iii) Since (C) reacts with acetyl chloride to form a popular pain killer (D), therefore (D) must be aspirin.
(iv) All the above reactions may be explained as follows: