Waiting
Login processing...

Trial ends in Request Full Access Tell Your Colleague About Jove

11.11: Apertura de Anillo de Epóxidos Catalizada por Ácido
TABLA DE
CONTENIDOS

JoVE Core
Organic Chemistry

A subscription to JoVE is required to view this content.
You will only be able to see the first 20 seconds.

Education
Apertura de Anillo de Epóxidos Catalizada por Ácido
 
TRANSCRIPCIÓN

11.11: Apertura de Anillo de Epóxidos Catalizada por Ácido

Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The reaction follows the SN2 mechanism, and the protonated oxygen, unlike other leaving groups, does not detach from the molecule. The regiochemistry of the products formed is governed by either steric or electronic effects. In the case of an asymmetrical epoxide bearing a primary and a secondary carbon, the steric effect dominates and favors the nucleophilic attack at a less-hindered carbon. However, in epoxides where one of the carbons is tertiary, the electronic effect comes into play and favors the attack at a more-hindered carbon. The stereochemistry of the products is similar to an SN2 reaction, where the nucleophile attacks anti to the leaving group. Notably, the anti-attack at a chiral carbon causes an inversion of configuration.

Get cutting-edge science videos from JoVE sent straight to your inbox every month.

Waiting X
Simple Hit Counter