Lecture Notes: Triglycerols and Ester Hydrolysis

Introduction to Triglycerols

• Triglycerols are hydrolyzable lipids.
• Can be broken down into smaller pieces via hydrolysis reactions.
• Specifically, they undergo ester hydrolysis, breaking down the ester bonds.

Ester Hydrolysis

• Ester: Carbon double-bonded to an oxygen and bonded to an OR group.
• Ester hydrolysis involves breaking these ester bonds.
• Can occur with either an acid or a base.

Base-Promoted Ester Hydrolysis

• Focus is on base-promoted hydrolysis due to its implications for triglycerols.

Reaction Mechanism

1. Nucleophilic Addition
   • OH group (base) attacks the carbon.
   • Results in a carbanion tetrahedral intermediate.
2. Formation of Carboxylic Acid
   • OR group leaves as a strong base.
   • Formation of a carboxylic acid.
3. Acid-Base Proton Transfer
   • OR group picks up the proton.
   • Results in a carboxylate anion and an alcohol.

Results and Significance

• This is the mechanism to start fat metabolism.
• Enzymes called lipases facilitate this reaction in the body.
• Reaction is crucial for energy metabolism from fat.

Saponification: An Application of Base-Promoted Ester Hydrolysis

• Saponification: The process of making soap from triglycerols.
• Use of a strong base like sodium hydroxide (NaOH).
• Formation of anionic salt (soap) from carboxylate anion and sodium cation.

Properties of Soap

• Long non-polar tail with a polar head (ionic bond).
• Non-polar tail dissolves grease and oil.
• Polar head dissolves in water, allowing soap to wash away dirt.

Conclusion

• Base-promoted ester hydrolysis is important for metabolism and soap production.
• Saponification refers specifically to this hydrolysis reaction in soap making.