Answer to Question #108140 in Organic Chemistry for Allah Ditta

Question

During S1 reaction. what is the significance of first step?

Answer 1

Solution:

S_N1 mechanism (1st step)::

1st step: slow loss of the leaving group, LG, to generate a carbocation intermediate. The more stable the carbocation is, the easier it is to form, and the faster the S_N1 reaction will be.

The first step of the reaction requires bond breaking (endothermic, heat in) to lose the leaving group, it will be the slow or rate determining step.

Therefore, the general kinetic expression for an S_N1 reaction is rate = k [R-LG].