What is esterification?
Esterification is when two reactants basically form an ester in the end. But you knew that.
A common one is called the Fischer esterification, which is when excess/xs alcohol reacts with a carboxylic acid in (other) acid.
Here is an example of a general carboxylic acid reacting with a general alcohol in
The mechanism is just like other nucleophilic addition-elimination reactions in your book.
#"HCl"#catalyst has already protonated your alcohol and the alcohol has already transferred the proton to the electron-rich carbonyl oxygen. Under these conditions, the regular alcohol can act as a good nucleophile.
- Proton transfer part 1.
- Proton transfer part 2.
- Now the water is a good leaving group, so the tetrahedral collapse occurs.
- The alcohol takes the proton off of the carbonyl oxygen to regenerate the dominant form of your
#"HCl"#catalyst (the protonated alcohol) and finish the reaction. The pKa of ethanol is about #15.9#, and water's is about #15.7#, so ethanol is more likely to want a proton.
You should notice that the