3
$\begingroup$

I understand why compounds such as $\ce{NaH}$ or $\ce{NaNH2}$ are weak nucleophiles: as they aren't very soluble in organic solvents, they react only on the clusters' surface. But why are they strong bases?

I could understand why they are in water, as they are soluble in water, but in my organic chemistry class it was said that they accelerate E2 reactions. So how can they be strong bases in organic solvents if they aren't soluble in organic solvents?

Improve this question
$\endgroup$
1
  • $\begingroup$ Huh, you provide somewhat surprising reasoning. I'd be interested how valid it. Major problem is they aren't exactly "soluble" in water - while they "dissolve" they also react and that's driving the process forward. Another thing is that they aren't completely insoluble in organic solvents, at least in the ones they are actually used. $\endgroup$
    – Mithoron
    Dec 11, 2019 at 1:44

2 Answers 2

Reset to default
2
$\begingroup$

H- and NH2- are both strong nucleophile and strong bases but we know that acid base reaction are very favourable and fast due to change in Gibbs free energy is highly negative. So they prefer acid base reactions first as their conjugate acids are H2 and NH3 which are very weak bases.

Improve this answer
$\endgroup$
0
$\begingroup$

You're right they're difficult to use in organic reactions because of the solubility problem you mention. However, by using crown ethers like dibenzo-18-crown-6 they can be captured and the crown ethers are subsequently dissolved so that the bases are "brought into solution" and react.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

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