E2 Mechanism Flashcards
What is an E2 mechanism?
This is a concerted, 1 step mechanism involving simultaneous bond formation and bond breakage
Takes place in presence of high concentration of base
What is the rate equation?
Rate= k[base][HX]
What does kinetics suggest about the reaction?
It suggests that the halogenoalkane and the base are involved in the transition state of the rate determining step
What type of reaction is this regarding the transition state?
Is it a bimolecular reaction as 2 reactant molecules are involved in the transition state
Describe the process of the reaction
1) the base attacks the hydrogen of the carbon adjacent to the one carrying the halogen atom
2) the base forms a new bond to the hydrogen atom at the same time as the CX bond is broken and the C=C bond is formed
Which conformation does the halogenoalkane adopt?
It adopts an antiperiplanar in which the H and C groups are in the same plane and on the opposite side of the molecule
The sigma orbital of the CH bond is parallel to the sigma antibonding orbital of the CX bond
When these orbitals are parallel they. An overlap side on as the H and X groups leave and rehybridise to form the overlapping p orbitals of the new C=C bond
What is the kinetic isotope effect?
If CH bond breakage is part of the rate determining step, then the replacement of H with D should slow down the rate of reaction
This is because D will form stronger bonds with carbon than H does
