Question
n-Butane on monochlorination under photochemical condition gives an optically active compound "P". "P" on further chlorination gives dichloro compounds. The number of dichloro compounds obtained (ignore stereoisomers) is:
JEE Main
Chemistry
Haloalkanes and Haloarenes
2026
JEE Main 2026 (08 April Shift 2)
JEE Main Chemistry Question (2026) — Solution
Options
- A. 3
- B. 4
- C. 5
- D. 6
Answer
B. 4
Step-by-step solution
The structure of n-butane is CH_3-CH_2-CH_2-CH_3. Monochlorination of n-butane gives two structural isomers: 1-chlorobutane and 2-chlorobutane. Among these, 2-chlorobutane (CH_3-CH_2-C^ * HCl-CH_3) contains a chiral carbon atom and is optically active. Thus, the optically active compound "P" is 2-chlorobutane. Further chlorination of 2-chlorobutane can take place at any of the four carbon atoms, yielding the following dichloro compounds (ignoring stereoisomers): 1. Chlorination at C-1: CH_3-CH_2-CHCl-CH_2Cl (1,2-dichlorobutane) 2. Chlorination at C-2: CH_3-CH_2-CCl_2-CH_3 (2,2-dichlorobutane) 3. Chlorination at C-3: CH_3-CHCl-CHCl-CH_3 (2,3-dichlorobutane) 4. Chlorination at C-4: CH_2Cl-CH_2-CHCl-CH_3 (1,3-dichlorobutane) Therefore, 4 structurally distinct dichloro compounds are obtained. Answer: 4
Related: Chemistry — Haloalkanes and Haloarenes · All PYQ Banks