Question

Question:(a) Draw all stereoisomers of molecular formula C₅H₁₀Cl₂ formed when (R)-2-chloropentane is heated with Cl₂ .

(b) Assuming that products having different physical properties can beseparated into fractions by some physical method (such as fractional distillation), how many different fractions would be obtained?

(c) Which of these fractions would be optically active?

Short answer

Answer

(a)

(b)Seven fractions

(c) Five fragments are optically active.

Step-by-step solution

Radical chlorination of alkane

You can achieve chlorination of alkane via a radical intermediate by treating the alkane with chlorine in the presence of light or heat. Chlorine as a reagent is unselective and thus gives a mixture of the product.

The mechanism of radical halogenations, taking methane as the alkane, is shown below:

Mechanism for radical chlorination

Chlorination of (R)-2-chloropentane

The chlorination of (R)-2-chloropentane is given below:

Chlorination of (R)-2-pentane

Each of the different products formed has some specific physical property different from the other. Thus, seven different fractions would be obtained.

A compound is known to be optically active when the carbon center is attached to four different groups or functionalities. Based on this, the optically active products are given below:

Optically active compounds