The drug shown is heated with excess aqueous sodium hydroxide until it is completely hydrolysed and all acidic groups of the products are neutralised. How many moles of NaOH are consumed per mole of the drug? Give the answer as an integer.

The compound shown is aspirin. One NaOH neutralises the COOH, a second hydrolyses the ester (giving acetic acid, which is neutralised, and a phenol), so the ester consumes 2 in all, and the phenol formed is then converted to phenoxide. Counting COOH 1 + ester hydrolysis with acetate formation 1 + phenol 1 gives: aspirin + 3 NaOH -> sodium acetate + disodium salicylate + 2 H2O. Answer 3.