There is considerable evidence that SN1 mechanism is followed in diazo aromatic compounds' nucleophilic substitution. I would like to know the reason for this and why is it preferred to SNAr mechanism even when the $\ce{N2+}$ could stabilize the carbanion-type intermediate through -I effect.

Does it have to do with the excellent leaving tendency of $\ce{N2+}$ but at the cost of formation of unstable phenyl cation?

  • 1
    $\begingroup$ Generally, you describe the leaving group as it would be it had left, in this case, dinitrogen ($\ce{N2}$). So, then you're looking at a heterolytic bond cleavage that is highly favorable against a bimolecular $S_{\mathrm{N}}Ar$ mechanism. Under concentrated conditions, the bimolecular mechanism might be competitive. $\endgroup$ – Zhe Apr 26 '18 at 19:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.