I understand that tert-butoxide is used to favor the Hofmann product in elimination reactions due to its steric bulk (and thus inability to abstract a proton in a more substituted position); however, I have often seen proposed organic synthesis involving the use of tert-butoxide when it is seemingly irrelevant. For example, 1-bromobutane will undergo an elimination reaction with or without a sterically hindered base (such as tert-butoxide); however, anytime I see reactions involving elimination reaction with primary substrates, such as the bromo group in 1-bromobutane, tert-butoxide is used rather than ethoxide. Is tert-butoxide simply used to disfavor the formation of substitution products. Is its steric bulk enough to not allow it to act as a good nucleophile in substitution reactions?


Several reasons:

  1. t-BuOK is especially known as a strong base, and a poor nucleophile. Its large, bulky structure causes it to perform exceptionally poorly in substitution, literally eliminating any side reactions when the desired product is the elimination product.

  2. It is easily available, like Raphaël insists.

  3. It's basic strength depends on the medium. It is very strong in DMSO, where the solvent complexates well with $\ce{K+}$ ions. However it is relatively weaker in benzene. This flexibility gives it inevitable popularity.

  4. Many condensation reactions (Stobe's, Darzen's) are seen to have greater yield when t-BuOK is used.


Generally, it's just because there's a big bottle of $\ce{t-BuOK}$ lying around, so why bother using something else?

In the same range of ideas, I've seen publications where they used $\ce{n-BuLi}$ to deprotonate an alcohol; it's completely overkill, but was probably just more convenient in their case than $\ce{NaH}$ or something else.


Your Answer

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

Not the answer you're looking for? Browse other questions tagged or ask your own question.