One way to think about concerted reactions is to imagine them as being stepwise reactions where, besides the slowest step, all others have infinitesimally small activation energies. Considering the hypothetical stepwise mechanism and actual concerted mechanism of epoxide formation, show what a reaction coordinate diagram might look like for each possibility.
(b) Concerted , actual mechanism (butterfly transition state:

Predict the product(s) when each of the following are reacted with mCPBA, making sure to indicate the relative stereochemical outcome. Indicate any racemic mixtures by drawing both enantiomers.

(a)

When producing a chiral molecule, epoxide formation still results in a mixture of enantiomers, despite its stereospecificity.

(b) How is it that a reaction can be stereospecific while still producing two enantiomers?

Rank the reactivity of the following alkenes with mCPBA ( 1 = most reactive , 5 least reactive ).

One way to think about concerted reactions is to imagine them as being stepwise reactions where, besides the slowest step, all others have infinitesimally small activation energies. Considering the hypothetical stepwise mechanism and actual concerted mechanism of epoxide formation, show what a reaction coordinate diagram might look like for each possibility.

(a) Stepwise, hypothetical mechanism:

How does the carbonyl in mCPBA weaken the O―O σ bond (i.e., make a better leaving group)?

Calculate the atom economy of the reaction in Figure 9.24. [Catalysts are not included in the atom economy calculation.]

Write the appropriate reagent over each arrow.

In addition to using mCPBA, epoxides can be synthesized from alkenes in the two-step process shown. Give a mechanism for each step of the process.