Question

The reactivity order of halides for dehydrohalogenation is.

• A. \(\text{R-F}>\text{R-Cl}>\text{R-Br}>\text{R-I}\)
• B. \(\text{R-I}>\text{R-Br}>\text{R-Cl}>\text{R-F}\)
• C. \(\text{R-I}>\text{R-Cl}>\text{R-Br}>\text{R-F}\)
• D. \(\text{R-F}>\text{R-I}>\text{R-Br}>\text{R-Cl}\)

Hint:

The weaker the C-X bond, the easier the elimination, so R-I is most reactive and R-F is least reactive.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
In dehydrohalogenation the carbon-halogen bond breaks, so reactivity depends on the bond strength and the leaving group ability.

Step 2: Compare the halogens
Bond strength: \(\text{C-F}>\text{C-Cl}>\text{C-Br}>\text{C-I}\).
Leaving group ability: \(\text{I}^{-}>\text{Br}^{-}>\text{Cl}^{-}>\text{F}^{-}\).

Step 3: Write the order
Reactivity: \(\text{R-I}>\text{R-Br}>\text{R-Cl}>\text{R-F}\).

Final Answer:
The reactivity order is R-I > R-Br > R-Cl > R-F. \[ \boxed{\text{(B) }\text{R-I}>\text{R-Br}>\text{R-Cl}>\text{R-F}} \]