Why does ozone cleave alkenes? [closed]








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I am studying additional reactions in organic chemistry and I am confused as to why ozone cleaves double bonds? I already know the mechanism of what happens but can anyone give a more conceptual understanding of why this occurs?




Analysis of the [frontier molecular orbitals](https://en.wikipedia.org/wiki/Frontier_molecular_orbital_theory) of the alkene and ozone molecules easily and elegantly predicts the occurrence of the first step of this reaction:


![](https://i.stack.imgur.com/dY39i.png)


The actual cleavage step forms a carbonyl and carbonyl oxide—a pair of molecules that are electronically identical to the starting reagents, but are thermodynamically favored over their regenration:


$$ \small
\begin{array}{lcc}
\hline
& \text{Bond Dissociation} & & \text{Bond Dissociation}\\
\text{Bond} & \text{Enthalpy}\ \mathrm{(kJ\ mol^{-1})} & \text{Bond} & \text{Enthalpy}\ \mathrm{(kJ\ mol^{-1})} \\
\hline
\ce{C-C} & 347 &\ce{C=C} & 614\\
\ce{O-O} & 146 & \ce{O=O} & 495\\
\ce{C-O} & 358 & \ce{C=O} & 745^{[1]}\\
\hline
\end{array}
$$


![](https://i.stack.imgur.com/LJHbT.png)


Formation of the secondary ozonide is also thermodynamically favored:


![](https://i.stack.imgur.com/3EKHY.png)




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$^{[1]}$[Bond Dissociation Enthalpy Tables](http://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Chemical_Bonding/General_Principles_of_Chemical_Bonding/Bond_Energies)


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