Question

Explain the dehydrohalogenation reaction of 2-chlorobutane. Write use and environmental effect of CFC.

Hint:

CFCs have been phased out under the Montreal Protocol due to their harmful environmental effects, particularly in depleting the ozone layer. Always check if a chemical has eco-friendly alternatives.

Answer 1

Step 1: Dehydrohalogenation of 2-Chlorobutane.
The dehydrohalogenation reaction involves the elimination of a hydrogen atom and a halogen atom (chlorine) from a compound. In 2-chlorobutane, the reaction occurs in the presence of a strong base like potassium hydroxide (\(KOH\)) to form 2-butene: \[ C_4H_9Cl + KOH \rightarrow C_4H_8 + KCl + H_2O \] This follows an E2 elimination mechanism, where both the base and substrate react simultaneously. Step 2: Use and Environmental Effect of CFCs.
Chlorofluorocarbons (CFCs) were once widely used as refrigerants, solvents, and in aerosol propellants. However, their use has been phased out due to their role in ozone layer depletion. CFCs break down ozone molecules in the stratosphere, leading to increased UV radiation reaching Earth, which causes skin cancer, cataracts, and other health issues.