An unknown hydrocarbon 'P' with the molecular formula C ₉ H ₁₂ is subjected to the following sequence of reactions: (i) Cl ₂ , FeCl ₃ Q (major product) (ii) Br ₂ , h (1 equivalent) R (iii) alc. KOH , 1 -chloro-4-(prop-1-en-2-yl)benzene The structure of the starting hydrocarbon 'P' is:

Step-by-step solution

The final product is 1-chloro-4-(prop-1-en-2-yl)benzene. The presence of a branched prop-1-en-2-yl side chain indicates that the elimination in step (iii) occurred from a 2-halopropan-2-yl group. Working backwards: Step (iii): Dehydrohalogenation of 'R' with alc. KOH yields the alkene. Thus, 'R' must be 1-chloro-4-(2-bromopropan-2-yl)benzene. Step (ii): 'R' is formed by benzylic bromination of 'Q'. This implies 'Q' has an isopropyl group, making it 1-chloro-4-isopropylbenzene. Step (i): 'Q' is formed by the electro