Page 21 Flashcards
What is the kinetic order of the E2 mechanism?
A: The E2 mechanism exhibits second-order kinetics, where the rate depends on both the substrate and the base.
How many steps are involved in the E2 mechanism?
A: The E2 mechanism occurs in one concerted step, where bond breaking and bond forming happen simultaneously.
Which substrates react the fastest in the E2 mechanism?
A: More substituted alkyl halides react fastest in the order R_3CX > R_2CHX > RCH_2X , due to greater stability of the transition state.
What type of base is favored in the E2 mechanism?
A: E2 reactions are favored by strong bases, which effectively abstract a proton from the β-carbon.
How does the leaving group affect the E2 reaction rate?
A: A better leaving group increases the reaction rate because it stabilizes the transition state and facilitates bond cleavage.
What type of solvent is favored in the E2 mechanism?
A: Polar aprotic solvents are favored as they do not solvate anions excessively, allowing the base to remain reactive.
Why are tertiary alkyl halides preferred in E2 reactions?
A: Tertiary alkyl halides stabilize the carbocation-like transition state better due to hyperconjugation and inductive effects from adjacent alkyl groups.
How does the strength of the base influence the E2 reaction?
A: Stronger bases increase the reaction rate by efficiently deprotonating the β-hydrogen and promoting elimination.
What is the role of the leaving group in the E2 mechanism?
A: The leaving group departs with the electron pair from the C-X bond, enabling the formation of a double bond between the α and β carbons.
How does the identity of R affect the transition state in E2 reactions?
A: More substituted R groups stabilize the developing partial positive charge on the β-carbon in the transition state, enhancing reaction efficiency.
