simple OchemQ

[sony102]

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when reacting aliphatic alcohol with a cyclic asymetric ether to open the ether, is the aliphatic alcohol considered an acid or a base??? I need to know because i need to figure out if it will attack the least substituted or the most substituted part of the ring

thanks

 

[klutzy1987]

when reacting aliphatic alcohol with a cyclic asymetric ether to open the ether, is the aliphatic alcohol considered an acid or a base??? I need to know because i need to figure out if it will attack the least substituted or the most substituted part of the ring

thanks

It depends on what catalst is used, not on the reagent. An acid catalyzed opens on the more substituted side while a base catalyzed opens on the less substituted side.

 

[mddang]

It depends on what catalst is used, not on the reagent. An acid catalyzed opens on the more substituted side while a base catalyzed opens on the less substituted side.

Yup... With an acid catalyst, the oxygen of the epoxide is protonated, and the alcohol will attack the more substituted end. Think carbocation formation.


With a base catalyst, the alcohol is deprotonated and an alkoxide anion is produced. The alkoxide anion is a strong nucleophile, and it will attack the carbon that has less steric hindrance.