Which of the following cannot form Grignard reagent?
(1) Bromo ethane
(2) Brome ethene
​(3) 3 Bromo prop-1-yne
(4) 3 Bromo prop-1-ene
answer is (3). Why?

Dear Student,

The formation of Grignard reagent proceeds through a mechanism which involves the formation of free radicals, which can be explained in the following figure:

enter image description here

Since a free radical containing a triple bond is highly unstable, this reaction is highly unfavourable.

Thus, 3-Bromoprop-1-yne does not from Grignard reagent.

Hope it helps.


  • 3
The compound (3) will have a triple bond in the carbon and it cannot undergo the reactikns undergone by Grignard reagents.
  • 0
What are you looking for?