Properties of esters

Properties of Esters

Overview of Esters

  • Ethyl acetate is highlighted as a common solvent found in fingernail polish, plastics, and lacquers.

  • Learning Objective:

    • Describe the boiling points and solubility of esters.

    • Draw condensed structural and line-angle formulas for products from acid and base hydrolysis.

Page 2: Boiling Points of Esters

Characteristics of Boiling Points

  • Esters exhibit:

    • Higher boiling points than alkanes and ethers.

    • Lower boiling points than alcohols and carboxylic acids of similar molecular weight.

  • Unlike alcohols, esters lack hydroxyl groups, which prevents them from forming hydrogen bonds with themselves, impacting their boiling points.

Page 3: Solubility of Esters in Water

Solubility Factors

  • Esters are soluble in water if they contain 2 to 5 carbon atoms.

  • As the carbon chain length exceeds five, solubility decreases.

  • The carbonyl group's partially negative oxygen can form hydrogen bonds with water's partially positive hydrogen atoms, contributing to solubility.

Page 4: Acid Hydrolysis of Esters

Reactions in Acid Hydrolysis

  • In acid hydrolysis, the following occurs:

    • An ester reacts with water to create:

      • A carboxylic acid.

      • An alcohol.

    • A water molecule donates a group, converting the carbonyl functional group into a carboxyl group.

    • Requires an acid catalyst and heat for the reaction to proceed.

Page 5: Aspirin Hydrolysis

  • Aspirin, when stored for extended periods, can undergo hydrolysis when exposed to water and heat, exemplifying the concept of ester hydrolysis in practical applications.

Page 6: Base Hydrolysis (Saponification)

Characteristics of Base Hydrolysis

  • Base hydrolysis, or saponification:

    • Involves the reaction of an ester with a strong base (e.g., NaOH) in heat.

    • Produces:

      • A carboxylate salt.

      • An alcohol.

Page 7: Learning Check 1

Problem Statement

  • Ethyl acetate is used as a solvent in multiple products.

  • Task: Write the balanced chemical equation for hydrolysis of ethyl acetate with NaOH.

  • Given: Ethyl acetate, NaOH

  • Need: Base hydrolysis equation.

  • Expected products: Carboxylate ion and alcohol.

Page 8: Solution 1

  • Reiteration of the task and the components involved in writing the balanced equation for the hydrolysis of ethyl acetate with NaOH focusing on the same details as the Learning Check.

Page 9: Learning Check 2

Problem Statement

  • Task: Write the balanced equations for the reactions of methyl acetate:

    • A: With water, heat, and an acid catalyst.

    • B: With KOH and heat.

Page 10: Solution 2

  • Similar task as above, requesting balanced equations for the reactions of methyl acetate in two separate conditions.

Page 11: Concept Map

Key Relationships in Esters and Carboxylic Acids

  • Carboxyl Group:

    • Esters can form hydrogen bonds and are soluble in water when containing up to 5 carbon atoms.

  • Relationship Overview:

    • Carboxylic acids and esters are connected through hydrolysis and saponification reactions, revealing the transformative nature of these compounds.

    • Carboxylic acids can dissolve in strong bases to form carboxylate salts and dissociate as weak acids, while esters are products of these reactions.