TBR ochem section 1 passage 13, question #85

[princesslinda]

The question asks which of the compounds is the MOST basic?
Primary alcohols, esters, secondary amines, tertiary thiols

The answer is secondary amines.

For the answer explanation in the back they state that esters have no lone pair of electrons that can be readily donated to a proton. Can any one explain this to me because I thought esters are able to donate electrons through the carbonyl carbon. Also, what is the reasoning why amines are most basic as compared to the rest of the compounds?

Thanks!

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[karafox]

The stronger the base, the more readily it will want to donate electrons (Lewis base definition).

Along with the non-bonding lone pairs on nitrogen on a secondary amine, (assumption) there are 2 electron-donating groups on a secondary amine, giving nitrogen more negative charge. This build up of negative charge will be up for donation of electrons.

To answer your question, the carbonyl carbon has a partial positive charge and will want to accept, not donate electrons.