# Identify structure of compounds from their reactions and molecular formula

Compound P($$\ce{C7H6O}$$) on refluxing with aqueous ethanolic $$\ce{KCN}$$ solution for 1 hour, forms Q($$\ce{C14H12O2}$$). Q on oxidation gives R($$\ce{C14H10O2}$$). R on refluxing with aqueous $$\ce{NaOH}$$ solution followed with acidification forms an $$\alpha-$$hydroxyacid S ($$\ce{C14H12O3}$$). What are the structures of the compounds?

### My effort:

P has DBE (double bond equivalent) equal to 8, so 2 benzene rings (not possible with 7 carbons) or some cyclic or many double bonds might be necessary. Now some enolate reaction might be happening with $$\ce{KCN}$$, like Aldol or Perkin or Knoevnagel or Stobbe or Claisen or Benzion etc. Oxidation doesn't affect the formula so it might be becoming an isomer (that too a functional one). After that a Cannizaro might be the thing.

You weren't far from resolution. The substrate is benzaldehyde, first reaction benzoin condensation, so Q is benzoin. It is later oxidated to benzil - R ($\ce{C14H10O2}$) (not ($\ce{H12}$) - in oxidation formula must change). Finally benzil undergoes benzilic acid rearrangement, so S is benzilic acid.