Chapter 24, Problem 24.21P

Interpretation Introduction

Interpretation:

A hydrocarbon having the formula ${\text{C}}_{\text{8}}{\text{H}}_{\text{14}}$ is treated with hot, basic, concentrated ${\text{KMnO}}_{\text{4}}$, followed by an acid workup. Bubbling is observed and the compounds shown below are recovered. The possible structures for the original hydrocarbon are to be determined.

Concept introduction:

When the concentrated ${\text{KMnO}}_{\text{4}}$ solution and hydrocarbon is heated significantly above room temperature, the oxidative cleavage of the $\text{C=C}$ bond takes place. The ${\text{MnO}}_{\text{4}}{}^{\text{-}}$ undergoes a $[4+2]$ cycloaddition to the double bond giving a manganite ester. The added heat, however, provides enough energy to break the C-C bond via another cyclic rearrangement of six electrons thus eliminating ${\text{MnO}}_{\text{2}}$. This step is more specifically a $[4+2]$ cycloelimination. By this step, the initial alkene C atoms have already been incorporated into carbonyl groups. The characteristic of carbonyl groups is aldehyde and ketone. Under the oxidation conditions, the aldehyde reacts further to produce carboxylic acid. When one of the alkenes is terminal then cleavage of the $\text{C=C}$ double bond initially produces formaldehyde. This formaldehyde on oxidation produces carbonic acid which degrades into ${\text{H}}_{\text{2}}\text{O}$ and ${\text{CO}}_{\text{2}}$.