How many products (including stereoisomers) are expected from monochlorination of the following compound?

CONCEPT:

Free Radical Chlorination and Stereoisomerism

• In free radical halogenation reactions, such as chlorination (Cl₂/hv), chlorine atoms replace a hydrogen atom on a carbon chain, leading to the formation of different products.
• The reaction proceeds via a radical mechanism, where a chlorine molecule (Cl₂) undergoes homolytic cleavage under the influence of light (hv), producing two chlorine radicals.
• The chlorine radical then reacts with a hydrogen atom on the carbon chain, resulting in the substitution of a hydrogen atom with a chlorine atom, forming a product and a new carbon-centered radical.
• For this type of reaction, stereoisomerism can occur if a chiral center is created, meaning two enantiomers (R and S) may form for each substitution site that creates a chiral center.

EXPLANATION:

• In the given compound:

  CH₃-CH₂-CH₂-CH₃ (butane)

  The monochlorination can occur at different positions along the carbon chain, specifically at the 2^nd and 3^rd carbon atoms, where the chlorine atom can replace a hydrogen atom.
• When chlorine atoms are substituted at the 2^nd and 3^rd carbons, they create chiral centers at those positions, leading to the formation of two stereoisomers (R and S forms) for each of these sites.
• 
• The possible products include:
  • Chlorination at the 2^nd carbon creates a chiral center, leading to 2 stereoisomers (R and S forms).
  • Chlorination at the 3^rd carbon also creates a chiral center, leading to 2 stereoisomers (R and S forms).
  • Chlorination at the 1^st and 4^th carbons does not create chiral centers and leads to only one product each.
• Thus, the total number of products formed from monochlorination, including stereoisomers, is 6: 2 from the 2^nd carbon, 2 from the 3^rd carbon, and 1 each from the 1^st and 4^th positions.

Therefore, the correct answer is Option (4) 6.