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Understanding Esters and Their Reactions

Dec 6, 2024

Esters Lecture Notes

Overview

  • Discussed esters and related reactions.
  • Topics covered: formation, naming, drawing, and hydrolysis of esters.

Formation of Esters

  • Reactants: Alcohol + Carboxylic Acid
  • Reaction Type: Condensation Reaction
    • Joins reactants and releases a water molecule.
    • Reversible reaction, related to chemical equilibria (covered in Unit 3).

Reaction Details

  • Condensation Reaction: Loss of water (H2O) when forming an ester.
    • Could involve loss of other small molecules like HCl.
  • Hydrolysis Reaction: Reverse process using water to split ester back to alcohol and carboxylic acid.
  • Oxygen from alcohol remains attached; forms ester link with carboxylic acid’s oxygen.

Naming Esters

  • Structure: Two parts—alcohol and carboxylic acid.
    • First part: Derived from parent alcohol, end changed to -yl (e.g., ethanol -> ethyl).
    • Second part: Derived from parent carboxylic acid, end changed to -oate (e.g., methanoic acid -> methanoate).
  • Examples:
    • Ethanol + Methanoic Acid = Ethyl Methanoate
    • Methanol + Propanoic Acid = Methyl Propanoate

Structure and Drawing of Esters

  • Start by drawing reactants: alcohol (e.g., CH3CH2OH) and carboxylic acid (e.g., HCOOH).
  • Join through ester link (O-C=O).
  • Examples of structures:
    • Ethyl Methanoate: CH3CH2O-CO-H
    • Methyl Propanoate: CH3O-C3H5O
  • Procedure:
    • Draw reactants facing each other.
    • Remove water: H from alcohol, OH from acid.
    • Join remaining parts.

Drawing Esters from Names

  • Breakdown by parts:
    • Alcohol group (e.g., ethyl = 2 carbons).
    • Carboxylic acid group (e.g., pentanoate = 5 carbons).
  • Example: Ethyl Pentanoate
    • Alcohol part: 2 carbons + oxygen
    • Acid part: 5 carbons + ester link

Hydrolysis of Esters

  • Process: Water used to separate ester into alcohol and carboxylic acid.
  • Example: Methyl Butanoate
    • Splits into methanol and butanoic acid.
    • Water splits, H joins alcohol, OH joins acid.
    • Draw ester and split oxygen link to restore reactants.
  • Final Example: Propyl Butanoate
    • Splits into propanol and butanoic acid.

Conclusion

  • Review of ester chemistry: reactions, naming, structures, and hydrolysis.
  • Encouragement to subscribe for more content.

Note: This summary is meant as a study aid covering the key concepts discussed in the lecture on esters.

Full transcript