I came across the following two details about m-xylene:

  1. m-Xylene is thermodynamically most stable compound among o-xylene, m-xylene, and p-xylene.

  2. m-Xylene is most reactive towards nitration and sulphonation among the others.

I did some research and was able to find valid reasons for both the statements, but they still seem to be contradicting each other. How can m-xylene be most stable as well as most reactive at the same time?

Could someone please clarify my doubt and also, add more specific details if required.


"In m-xylene, the two methyl groups reinforce one another in their activation 
of the ring, while in o- and p-xylenes the methyl groups cancel the ring 
activation to some extent."

I totally agree with this statement and it clearly explains the reason behind the the reactivity of m-xylene towards nitration and other such reactions.

But I realized that I was considering this statement as the reason behind the stability of m-xylene as well. Reference: Thermodynamic stability of meta-xylene over ortho- and para-isomers

The reasoning seems to be fitting for both the cases (I do realize now that stability and reactivity are not opposing terms necessarily).

So, is the reason why m-xylene is most thermodynamically stable the same reason why m-xylene is most reactive towards nitration? Could someone please confirm this or add their inputs if I am making some mistake in correlating terms or in my reasoning.

  • 5
    $\begingroup$ Stability and reactivity have only a superficial relationship. Stability is about energies. Reactivity depends on activation energies which in turn depend not only on the energy of the starting material, but also the energy of the transition state. $\endgroup$
    – orthocresol
    Apr 28 '21 at 17:40
  • $\begingroup$ @orthocresol Thank you for your explanation, I understand it now $\endgroup$
    – Pal
    Apr 28 '21 at 18:01
  • 2
    $\begingroup$ @Pal If you got your answer, feel free to self-answer it. Self-answering is always encouraged and it will also help future readers. $\endgroup$ Apr 29 '21 at 2:26

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