Characteristics of E2 Mechanism 4. E2 elimination requires that H and L be anti to occur. In order for a bond to form, how must the p orbitals be arranged? a. perpendicular b. coplanar c. 45 angle d. doesn’t matter
Characteristics of E2 Mechanism The 2 transition states shown are in specific conformations. (anti) staggered and eclipsed anti elimination syn elimination “backside displacement” “frontside displacement” Which transition state would you expect to be more stable? a. anti b. syn c. ~ same
Characteristics of E2 Mechanism • Can anti elimination occur in both conformations? a. yes b. no c. neither
Note in the following slide that one can talk about the stability of the transition states and conduct a discussion on the products being both the kinetic and thermodynamic products. Also note that (d) is only partially correct because it doesn’t address why the more substituted alkenes form.
Characteristics of E2 Mechanism • In the following reactions, it is possible for an H to be anti to give each of the products without difficulty. Why are these product ratios observed? a. most stable alkene forms b. alkene forms from C with more H’s to lose (statistical) c. most volatile alkene forms d. alkene with least torsional strain forms