Question

Consider the following reaction and find the incorrect option(s) regarding the product(s).

• A. Number of optically active compounds formed are 10
• B. Number of pairs of enantiomers is 5
• C. Number of pairs of diastereomers formed is 4
• D. Number of fractions in which the mixture can be separated out by fractional distillation is 4

Answer 1

Answer: (A), (B)

The correct options are
A Number of optically active compounds formed are 10
B Number of pairs of enantiomers is 5

Lets mark the carbons as shown below:

(I) Chlorination at 1 or 1' carbon gives an enantiomeric pair.

(II) Chlorination at 3 or 3' carbon generates a new chiral centre. Thus, it gives a pair of enantiomers and diastereomers each.

(III) Chlorination at 4 or 4' gives a pair of enantiomers.

So total compounds formed = 8
All compounds have chiral centres and are optically active.
Enantiomeric pairs = 4
Diastereomeric pairs ${=}^4{C}_2-4=4$
Since enantiomers have similar physical properties like boiling point, they can be separated into a single fraction.

Therefore, the number of fractions to separate the mixtures using fractional distillation = 4