Chapter 26, Problem 26.53P

Interpretation Introduction

Interpretation:

To synthesize linear polyethylenimine instead of the branched form (Problem 26.51), $\text{2-ethyl-2-oxazoline}$ can undergo ring-opening polymerization, followed by a chemical modification of the side groups. How to carry out the chemical modification after polymerization is to be proposed.

Concept introduction:

In a ring-opening polymerization, cyclic monomers produce an acyclic polymer. After polymerization, prior to the chemical modification, the polymer’s repeating unit contains an $\text{O=C-N}$ group, characteristic of an amide. After chemical modification, the functional group is $\text{C-N}$, characteristic of an amine. To carry out this transformation, a nucleophilic addition-elimination is required, which will eliminate the $\text{N-}$ containing portion as a leaving group.