9P - Organic Chemistry (Mcmurry)

Question

Why do you suppose ketone halogenations in acidic media are referred to as being acid-catalyzed, whereas halogenations in basic media are base-promoted? In other words, why is a full equivalent of base required for halogenation?

Step-by-Step Solution

Answer

You need to explain why a full equivalent of base required for halogenation of ketone.

Step 1: Solution of the problem

The product of a base promoted halogenation is more reactive than that of acid catalyzed.

Step 2: Explanation of the solution

 

From the above reaction you can see that the electronegative halogen is on a carbon. This makes the product of a base promoted halogenation more reactive.

 

The electron withdrawing tendency of halogen makes the carbon more acidic which helps the reaction go further.

 

Step 3: Conclusion

Hence, for the above reason a full equivalent of base required for halogenation of ketone.