Chapter 13, Problem 66IP

Interpretation Introduction

Interpretation: The difference in Regiochemistry between two reactions to be explained.

Concept Introduction:

Ring-opening of Epoxide: Generally, Epoxide has significant ring strain and undergoes reactions in which the ring is opened relieves the ring strain. Ring–opening involves under a strong Nucleophile or an acid-catalyzed conditions.

Two step mechanistic ways:

1. I. Nucleophile attack 
2. II. Proton transfer.

Regiochemistry: The Nucleophile attack at the less substituted position of an epoxide, in the presence of unsymmetrical epoxide.

Stereochemistry: The Nucleophile attack at the chiral center occurs via ${\text{S}}_{\text{N}}\text{2}$ process; resulting an inversion of configuration.

Steric effects: out of two carbons attached to oxygen atom, one carbon of primary and other of secondary then the steric effects dominate, in which Nucleophile attacks the less hindered position.

Electronic effects: out of two carbons attached to oxygen atom, one carbon is tertiary and other carbon is primary then the electronic effects dominate, in which Nucleophile attacks the more substituted position.

To Identify: The difference in stereochemistry outcome of given two reactions to be explained.