Question #e1140

1 Answer
May 24, 2015

The third step in the Baeyer Villiger oxidation is the rate determining step because it involves the cleavage of a covalent bond.

Approximate rate constants for the steps are:

  • Step 1 = 10^4 to 10^9 " L·mol"^-1"s"^(-1)
  • Step 2 = 10^10 " L·mol"^-1"s"^(-1)
  • Step 3 = 10^(-6)" s"^(-1)
  • Step 4 = 10^4 to 10^9 " L·mol"^-1"s"^(-1)

Since no reaction can go faster than its slowest step, Step 3 is the rate determining step.

Step 1 is a simple OH proton transfer.

Such reactions are fast, with rate constants ranging from 10^4 to 10^9 "L·mol"^-6"s"^(-1).

Step 2 is the addition of an anion to a cation to form a neutral molecule.

These reactions are also very fast, with rate constants of about 10^10 "L·mol"^-6" s"^(-1)

Step 3 is the decomposition of the acyl peroxide (the Criegee intermediate).

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This involves the cleavage of a covalent O-O bond.

This is a much slower process. For example, the rate constant for the decomposition of t-butyl peroxyacetate is about 10^(-6)" s"^(-1).

Step 4 is another rapid proton transfer.