Chapter 10, Problem 10.26P

Interpretation Introduction

(a)

Interpretation:

The complete, detailed mechanism of the given reaction is to be drawn and the product of the reaction is to be predicted.

Concept introduction:

Epoxides react readily under neutral, basic, or acidic conditions. Epoxides can undergo nucleophilic substitution reactions in these reaction conditions to relieve the ring strain, and this compensates for the poor leaving group ability of alkoxides (${\text{RO}}^{-}$). The mechanism for the epoxides under neutral or basic conditions consists of an ${\text{S}}_{\text{N}}\text{2}$ step followed by a proton transfer reaction. Under neutral or basic conditions, a nucleophile attacks an epoxide at the least substituted carbon atom (less sterically hindered) of the ring, from the side opposite to the oxygen atom.

Interpretation Introduction

(b)

Interpretation:

The complete, detailed mechanism for the given reaction is to be drawn and the product of the same reaction is to be predicted.

Concept introduction:

Epoxides react readily under neutral, basic, or acidic conditions. Epoxides can undergo nucleophilic substitution reactions in these reaction conditions so as to relieve the ring strain, and this compensates for the poor leaving group ability of alkoxides (${\text{RO}}^{-}$). Under acidic conditions, the first step is the protonation the $\text{C}-\text{O}$ bond. This generates a partial positive charge on the carbon atoms in the epoxide. In the second step, a nucleophile attacks at the most substituted carbon atom in the epoxide from the side opposite the $\text{C}-\text{O}$ bond.