Question

E1 mechanism does not show isotope effect and e2 mechanism does not give rearranged product. Explain

Answer 1

E1 mechanism proceeds via a intermediate state by the formation of cation, that is  a positive charge on the carbon atom, so that there is enough time for the produced carbocation to become stable via rearrangement. So the E1 mechanism may lead to rearranged product.

In case of E2 mechanism the reaction proceeds via a transisnary state , that is there is no formation of carbocation, which leads to no rearrangement in product, but the isotope effect such as cis or trans may form due to steric effect.