Chapter 24, Problem 24.13YT

Interpretation Introduction

Interpretation:

The curved arrows for the given reaction are to be drawn.

Concept introduction:

The entropy term in a Diels-Alder reaction is negative because the reaction decreases the number of independent molecules (i.e., the reaction leads to less “disorder”). This means that increasing the temperature makes ${\text{ΔG}}^{\text{o}}{}_{\text{rxn}}$ less negative (because ${\text{ΔG}}^{\text{o}}{}_{\text{rxn}}$= ${\text{ΔH}}^{\text{o}}{}_{\text{rxn}}$-${\text{TΔS}}^{\text{°}}{}_{\text{rxn}}$). Under normal conditions, the prototypical Diels-Alder has a substantially negative change in standard free energy, giving it a very large equilibrium constant. As a result, the reaction is irreversible.