Question

Propane molecule on chlorination under photochemical condition gives two di-chloro products, "x" and "y". Amongst "x" and "y", "x" is an optically active molecule. How many tri-chloro products (consider only structural isomers) will be obtained from "x" when it is further treated with chlorine under the photochemical condition?

• A. 3
• B. 2
• C. 5
• D. 4

Hint:

Optically active compounds are those that have chiral centers. In this case, the addition of chlorine at various positions leads to a variety of structural isomers.

Answer 1

The Correct Option is A

To determine the number of trichloro derivatives from optically active 1,2-dichloropropane:

1. Identification of Compound "x":
The optically active dichloro product must be 1,2-dichloropropane (CH₃CHClCH₂Cl) as it contains a chiral center at C-2.

2. Possible Trichloro Products:
Chlorination can occur at three distinct positions:

1. Methyl group chlorination:
   CH₃CHClCH₂Cl → CCl₃CHClCH₂Cl
2. Chiral center chlorination:
   CH₃CHClCH₂Cl → CH₃CCl₂CH₂Cl
3. Terminal chloromethyl group:
   CH₃CHClCH₂Cl → CH₃CHClCHCl₂

3. Isomer Count:
These substitutions yield three distinct structural isomers. No additional unique structures are possible through single hydrogen substitutions on this compound.

The number of possible trichloro structural isomers is 3.