NEETChemistryHydrocarbons
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): In the presence of peroxide, addition of HBr to but-1-ene yields 2-bromobutane as the major product, while addition of HI yields 1-iodobutane. Reason (R): The H-I bond is weaker than the H-Br bond, causing iodine free radicals to combine to form iodine molecules instead of adding to the double bond
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
D. (A) is false but (R) is true
Step-by-step solution
The Assertion (A) is false. The addition of HBr to unsymmetrical alkenes like but-1-ene in the presence of peroxide follows anti-Markovnikov's rule, yielding 1-bromobutane as the major product. However, the peroxide effect is not observed with HI. The addition of HI always follows Markovnikov's rule, even in the presence of peroxide, yielding 2-iodobutane. The Reason (R) is true. The peroxide effect fails for HI because the H-I bond is relatively weak. As a result, the iodine free radicals generated during the reac