Chapter 27, Problem 27.57AP

Interpretation Introduction

(a)

Interpretation:

The reagent required to convert the corresponding chloromethyl polystyrene resin into the given resin is to be stated.

Concept introduction:

In the first order nucleophilic substitution reaction, ${\text{S}}_{\text{N}}1$, the reaction takes place through a carbocation intermediate. Therefore, stereochemistry of the molecule remains same in this reaction. Presence of a base facilitates the reaction by increasing the polarity of molecules.

Interpretation Introduction

(b)

Interpretation:

The order of the emergence of given amino acids in the column, when they are suspended in a $\text{pH}6$ buffer, is to be stated.

Concept introduction:

The amino acids may have net charge on them; they may be negatively charged or positively charged. According to this charge, the resins are chosen for elution of the acids. The anion exchange resin binds more strongly with anions having higher negative charge and loosely with cations having higher positive charge.

The $\text{pH}$ at which the amino acid molecule carries no net electric charge is known as it’s isoelectric point, $\text{pI}$. Above or below this $\text{pH}$, they will behave as cation or anion according to their structure.