Why OH- is not a stronger nucleophile than OR-?

[Toofh]

Can someone explain why choice D is wrong? OH- is smaller than OR-, and it is unstable, so I thought it is better nucleophile.

---

Members don't see this ad.

 

[KineticFlow603]

Doesn't the alkyl group donate electrons to the oxygen, which makes OR more reactive and unstable than OH-? That is why tertiary carbocations are more stable than primary or secondary, also alkyl anions are more stable than tertiary anions because it doesn't have alkyl groups that donate more negativeness to the carbanion.

 

[dhk2131]

The above two responses are correct. If you're looking at Oxygen specifically being the main factor in nucleophility, you'd want to ensure that it is electron-rich to be a good/better nucleophile. The R group is an EDG (as you've seen in EAS), and thus increases the electron density for oxygen to perform a nucleophilic attack.