Fischer Esterification question

[katie7]

I have a couple of questions about Fischer esterification. I understand that Fischer esterification must happen in acidic conditions in order to give an appropriate leaving group (H2O not -OH) but I don't understand why it is the C=O oxygen that is protonated and not the C-OH oxygen?

My second question is say you had a molecule like para-aminobenzoic acid. Since N is both a better base and a better nucleophile than O, why would the N not be protonated by an acid catalyst instead of the O?

Thanks for your help!

[chrisf]

I will attempt to answer this question this weekend.