Basicity of t-butoxide vs ethoxide

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In summary, T-butoxide is more basic than ethoxide, which affects their reactivity in nucleophilic substitution reactions. This is due to the presence of bulky t-butyl groups in t-butoxide, which stabilize the negative charge on the oxygen atom and increase its basicity. The polarity of the solvent can also influence the basicity of both compounds, with more polar solvents decreasing their basicity. Additionally, steric hindrance caused by the bulky t-butyl groups in t-butoxide can further increase its basicity by preventing the approach of other species to the oxygen atom.
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newyorkcity
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why is t-butoxide a stronger base than ethoxide?
 
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  • #2
The difference between those two is the two extra methyls on the t-butoxide. Care to guess what methyl groups do to an adjacent charge?
 
  • #3
i honestly don't have a clue. the only thing relevant i can think of is that a more highly substituted carbon atom will form a more stable radical / carbocation. I'm not sure what this might imply in this situation, if anything.

..?
 
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  • #4
Read up some more on the electronic effects of the methyl group.
 
  • #5


The basicity of t-butoxide and ethoxide can be compared by looking at their respective conjugate acids, t-butanol and ethanol. The conjugate acid of t-butoxide (t-butanol) has a more stable and less acidic proton compared to the conjugate acid of ethoxide (ethanol). This is due to the presence of four bulky t-butyl groups in t-butanol, which provide steric hindrance and make it difficult for the proton to dissociate. In contrast, ethanol has only one methyl group, which does not provide as much steric hindrance.

In addition, the negative charge on the oxygen atom of t-butoxide is more delocalized and therefore more stable compared to the negative charge on the oxygen atom of ethoxide. This is because the t-butyl groups in t-butoxide can donate electron density to the oxygen atom, making it more basic.

Therefore, t-butoxide is a stronger base than ethoxide due to the combined effects of steric hindrance and electron delocalization, which make the conjugate acid of t-butoxide more stable and less acidic than the conjugate acid of ethoxide.
 

1. What is the basicity of t-butoxide compared to ethoxide?

T-butoxide is more basic than ethoxide.

2. How does the basicity of t-butoxide and ethoxide affect their reactivity?

The higher basicity of t-butoxide means it is more reactive in nucleophilic substitution reactions compared to ethoxide.

3. Why is t-butoxide more basic than ethoxide?

This is due to the presence of bulky t-butyl groups in t-butoxide, which stabilize the negative charge on the oxygen atom, making it easier to accept a proton and increasing its basicity.

4. Can the basicity of t-butoxide and ethoxide be influenced by solvent choice?

Yes, the basicity of both compounds can be affected by the polarity of the solvent. More polar solvents can stabilize the negative charge on the oxygen atom, decreasing the basicity of both t-butoxide and ethoxide.

5. How does steric hindrance impact the basicity of t-butoxide and ethoxide?

The presence of bulky t-butyl groups in t-butoxide leads to steric hindrance, which increases the basicity by preventing the approach of bulky species to the oxygen atom.

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