Q29-4P - Organic Chemistry (Mcmurry)

Question

PROBLEM 29-4 Write a mechanism for the dehydration reaction of $\mathbf{\beta }\mathbf{-}$hydroxybutyryl ACP to yield crotonyl ACP in step 7 of fatty-acid synthesis.

Step-by-Step Solution

Answer

In step 7 of fatty acid synthesis, the dehydration of $\mathbf{\beta }\mathbf{-}$hydroxybutyryl ACP to give crotonyl ACP is an ${\mathrm{E}}_1\mathrm{CB}$, or Elimination by conjugate base mechanism.

Introduction to the Concept

Dehydration synthesis is a chemical reaction that joins two smaller molecules by eliminating atoms from each of them.

Solution Explanation

The alkene is formed in the reaction when the base extracts an ${\mathrm{H}}^{+}$ ion  and transfers it to a trans- lin of the hydroxide ${}^{-}\mathrm{OH}$.

In a natural biological response of metabolism, elimination has an anti-stereochemistry impact.