Question
The compound (X) on (i) on heating in the presence of anhydrous AlCl_3 and HCl gas gives 2,4-dimethyl pentane (ii) aromatization gives toluene and (iii) cyclisation gives methyl cyclohexane The correct name of compound (X) is:
JEE Main
Chemistry
Hydrocarbons
2026
JEE Main 2026 (02 April Shift 2)
JEE Main Chemistry Question (2026) — Solution
Options
- A. Hept-2-ene
- B. Hept-1,3,5-triene
- C. Heptane
- D. Hept-2,4,6-triene
Answer
C. Heptane
Step-by-step solution
Compound (X) undergoes isomerization on heating with anhydrous AlCl_3 and HCl gas to give branched-chain alkanes. The formation of 2,4-dimethylpentane (a 7-carbon branched alkane) indicates that (X) is a 7-carbon straight-chain alkane. Aromatization of n-heptane at high temperature and pressure in the presence of oxides of V, Mo, or Cr supported over alumina gives toluene. Cyclisation of n-heptane under similar conditions initially yields methylcyclohexane, which can further undergo dehydrogenation to form toluene. Since all these reactions are characteristic of n-heptane, compound (X) is heptane. Answer: Heptane
Related: Chemistry — Hydrocarbons · All PYQ Banks