A trisubstituted compound ' A ', C 10 H 12 O 2 gives neutral FeCl 3 test positive. Treatment of…

The trisubstituted compound '$\mathrm{A}$', ${\mathrm{C}}_{10}{\mathrm{H}}_{12}{\mathrm{O}}_2$ gives neutral ${\mathrm{FeCl}}_3$ test positive, means the compound is phenol. Phenol on treatment with $\mathrm{NaOH}$ and ${\mathrm{CH}}_3\mathrm{Br}$ gives ${\mathrm{C}}_{10}{\mathrm{H}}_{11}{\mathrm{O}}_2{\mathrm{CH}}_3$. The given compound is reacting with hot conc. $\mathrm{NaOH}$ gives a compound $\mathrm{B}$, ${\mathrm{C}}_{10}{\mathrm{H}}_{12}{\mathrm{O}}_2$. The reaction is Cannizzaro's reaction. Hence, compound must be benzaldehyde derivative. Compound '$\mathrm{A}$' also decolourises alkaline ${\mathrm{KMnO}}_4$, means compound contains an alkyl group attached to benzene ring. Hence, the structure of the compound can be written as follows,

The reactions are shown below.