Question

When chlorine is passed through propene at $400^{\circ} C,$ which is the following is formed?

• A. PVC
• B. Allyl chloride
• C. Nickel chloride
• D. 1,2-dichloro ethane

Answer 1

The Correct Option is B

To determine which product is formed when chlorine is passed through propene at 400^{\circ} C, we need to consider the type of reaction that takes place as well as the reactants involved.

• Propene (\mathrm{C_3H_6}) is an alkene, which means it contains a double bond. This makes it susceptible to reactions such as halogenation and addition reactions.
• When chlorine (Cl₂) is introduced to an alkene like propene at high temperatures, a substitution reaction typically occurs. This results in the formation of an allylic chloride since the temperature is conducive for allylic substitution rather than addition.

In this specific scenario, the reaction proceeds with the substitution of a hydrogen atom on the carbon adjacent to the double bond with a chlorine atom:

The reaction can be represented as:

\mathrm{CH_2=CH-CH_3 + Cl_2 \rightarrow CH_2=CH-CH_2Cl + HCl}

This reaction forms allyl chloride. The allylic position (next to the double bond) is more stable due to resonance, and hence, it tends to favor substitution at high temperatures.

Now let's evaluate the options:

• PVC (Polyvinyl Chloride): This is a polymer formed through the polymerization of vinyl chloride. This is not formed in this reaction.
• Allyl chloride: As discussed, this is the correct product of the reaction.
• Nickel chloride: This compound is unrelated to the reaction involving propene and chlorine.
• 1,2-dichloroethane: This product is typically formed by the addition of chlorine to ethene, not propene. Hence, it is not formed in this reaction.

Thus, the correct answer is Allyl chloride.