Lactones are cyclic esters that are obtained by intramolecular esterification from molecules containing acid and alcohol groups. This cyclization forms 5- or 6-membered cycles.
The mechanism of this reaction occurs in the following steps:
Stage 1. Protonation of the carboxylic group
![synthesis-lactones sintesis-lactonas](/images/stories/organica-ii/acidos-carboxilicos/sintesis-lactonas/sintesis-lactonas-02.png)
Step 2. Nucleophilic addition of the alcohol to the carboxylic group (cyclization step)
![synthesis-lactones sintesis-lactonas](/images/stories/organica-ii/acidos-carboxilicos/sintesis-lactonas/sintesis-lactonas-03.png)
Stage 3. Acid-base balance
![synthesis-lactones sintesis-lactonas](/images/stories/organica-ii/acidos-carboxilicos/sintesis-lactonas/sintesis-lactonas-04.png)
Stage 4. Water removal
![synthesis-lactones sintesis-lactonas](/images/stories/organica-ii/acidos-carboxilicos/sintesis-lactonas/sintesis-lactonas-05.png)