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My book says that in presence of excess aluminium chloride, when toluene reacts with methyl iodide, meta-xylene is the major product. Why aren't ortho-para products favored here?

Edit: The book is "Higher Secondary Chemistry Second Paper", third edition (reprint: 2013) by Haradhan Nag. The reaction is given on page 292.

Tahsin Choudhury
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    The o and p xylenes formed rearrange to more stable m-xyle in presence of $\ce{AlCl3}$ – Adithya Oct 08 '21 at 11:34
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    See this: https://pubs.acs.org/doi/pdf/10.1021/ja01626a038 – Adithya Oct 08 '21 at 11:43
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    meta xylene is more thermodynamically stable, so if you heat enough then you will get meta as your major product. – napstablook Oct 08 '21 at 12:34
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    Huh, that's cool. TIL. The HC Brown paper above pre-dates the Woodward-Hoffmann rules, but presumably the rearrangement is via a suprafacial (thermally allowed) pericyclic 1,5-carbon shift in the intermediate cation? – PCK Oct 08 '21 at 12:49
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    @TahsinChoudhury Don't forget to add to add reference to the book you refer to; at least author, title, publisher, edition/year of print. (Though, if is a book, adding the page number would be great.) – Buttonwood Oct 08 '21 at 13:26
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    @Buttonwood It is a Bangladeshi high-school textbook with many errors. It is not reliable, so I did not add any reference. – Tahsin Choudhury Oct 08 '21 at 13:33
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    @Jayadithya This is interesting because it contrasts with the direction rules taught and a brief run on molcalc.org yields free energies/heats of formation suggesting (at their level of computation engaged), the p-xylene were the most stable one: $\pu{22.83 kJ/mol}$ (o-xylene), $\pu{20.12 kJ/mol}$ (m-xylene), and $\pu{20.01 kJ/mol}$ (p-xylene). – Buttonwood Oct 08 '21 at 13:34
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    @TahsinChoudhury I don't mind if the source is a small or big author/school/publisher I do not know (yet). Reading the freely accessible first page of an earlier article by McCauly (1952JAmChemSoc6246) interestingly indicates the product distribution depends (at least) on catalyst, catalyst loading, and temperature and «the right conditions» indeed may favour the eventual formation of m-xylene. – Buttonwood Oct 08 '21 at 13:55
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    Related: Thermodynamic stability of meta-xylene over ortho- and para-isomers – orthocresol Oct 08 '21 at 14:41

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Alkylation seems to be reversible under duress. To make a decent analysis product ratios and times would be informative. The initial formation of ortho and para is because of lower activation energies. If they can equilibrate meta is favored over ortho because of steric effects and over para because there are twice as many meta and the electronic effect that stabilizes the transition state should actually raise the energy of the para ground state. Subtle perhaps but it does not take much energy difference to change close product ratios.

jimchmst
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