Download Ch 13 Esters

Chapter 13.3
Esters
Esters
• Are the aromas found in many fruits:
pineapple, mint, strawberries…
• Esters are synthesized easily by heating
carboxylic acid and alcohol in the presence of
an acid catalyst H2SO4, H3PO4
• Ex: Aspirin Synthesis
Esterification Rx
Acid
Carboxylic Acid + Alcohol →
Ester + H2O
Ethanoic Acid Methanol
Methyl ethanoate
Naming Esters
carboxylic acid
alcohol
• Identify carboxylic acid (contains carbonyl)
and alcohol parts
• Name: 1. alcohol part 2. carboxylic acid part
1. Alcohol: carbon chain of alcohol named as
alkyl: Ethyl
2. Carboxylic acid: carbon chain of carboxylic
acid named as carboxylate salt: propanoate
• Combine: Ethyl propanoate
Practice Naming
Ethyl 3-bromo-2chloropropanoate
3-methylbutyl butanoate
Acid Hydrolysis of Esters
• Reversal of Esterification Rx
• Heating of esters in the presence of a strong
acid (usually H2SO4, H3PO4 )
• Ester splits into carboxylic acid and alcohol
H2SO4
Ester + H2O → Carboxylic Acid + Alcohol
Acid is a catalyst!!!
What’s a catalyst?
Base Hydrolysis of Esters
• Heating of esters in the presence of a strong
base (NaOH, KOH)
• Product: Carboxylate salt and alcohol
• This Rx is also called saponification – used in
soap making
soap
Properties of Esters
• What intermolecular forces do esters have/not
have?
• Rate their boiling/melting point. Which molecule
group is higher/lower than esters?
• Esters form 4 dipoles, but no H-bonds!
• Boiling point is higher than ether (3 x dipole) but
lower than alcohols (2 x dipole, 1x H-bond)
BP of Esters