
Isomer $(P) \Rightarrow$ Can be prepared by Gabriel phthalimide synthesis
Isomer $(Q) \Rightarrow$ Reacts with Hinsberg's reagent to give solid insoluble in $NaOH$
Isomer (R) $\Rightarrow$ Reacts with $HONO$ followed by $\beta$-naphthol in $NaOH$ to give red dye.
Isomers $( P ),( Q )$ and $( R )$ respectively are

(image) $\xrightarrow{{SOC{l_2}}}\,B\,\xrightarrow{{N{H_3}}}\,C$$\,\xrightarrow[{B{r_2}}]{{NaOH}}\,D$
