Can Tert-butoxide displace bromide via SN2 reaction? I read that Tert-butoxide is bulky and has steric hindrance, even with primary substrates. How is this reaction (picture below) possible?

Source: Levy, Arrow pushing in Organic Chemistry

enter image description here

  • 2
    $\begingroup$ Well, either substitution or elimination can occur. In case of bromomethane, theres no question of whether eliminations can occur or not. So tert-butoxide did the expected thing, it substituted the bromine. By the way, its not that hindered to not approach methyl carbons. $\endgroup$ – Pritt Balagopal Apr 27 '17 at 14:50

This seems interesting. The $(CH_3)_3CO^-$ is a strong nucleophile and we observe here methyl bromide is being attacked and there is no point of elimination. There has to substitution in this case. The bulkier the nucleophile is the more probable is the elimination product due to steric hindrance. In majority of the cases Tert-butoxide undergoes elimination reaction. The further factor includes temperature at which the reaction is being carried out. enter image description here

We can show this relation with $$\delta G = \delta H - T \delta S$$ Hope it was helpful.


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