Question

Explain why the following compound is not stable

Short answer

The compound is not stable due to angle strain in its conformer along the triple bond. There is about 60° angle strain.

Step-by-step solution

Stability of a molecule

A compound becomes unstable due to the angle strain. Mostly this stained conformer is obtained for cyclic molecules.

Reason of unstability

The triple bond carbons are sp hybridized and the others carbons are sp³ hybridized orbitals. The most stable form of a cyclohexane is chair conformer. For sp orbitals, the angle becomes 180° and in case of the above structure, angle will be different and the angle can be calculated using Baeyer formula.

180^o-(360^o/n)

nin this formula is no of carbon atom in a compound.

For hexagon, the angle will be = 80^o-(360^o/6)=120^o

The angle strain becomes (180°-120°) = 60° which is a huge angle strain for the sp carbon. So, for that reason, the above structure is unstable.