Esters
Kaitlyn Picavet, Natalie Williamson, Sidney
Wittman, Vivian Ly
General Structure
O
||
R – C – O – R’
• The general formula of an ester is written as
RCOOR’
Where RCO = carboxylic acid
And where OR’= alcohol
Nomenclature
• Esters are made up of 2 alkyl groups and 2 oxygen
atoms.
• The alkyl groups and oxygen come from the
carboxylic acid and alcohol used in esterification
(the formation of esters).
Ethanol + Butanoic Acid  Ethyl Butanoate + Water
Alcohol
Carboxylic Acid
Ester
The name follows the pattern
____yl ____oate
• The first blank comes from the alcohol
-drop the -anol
-add -yl
ie) ethanol would be ethyl.
• The second blank comes from the carboxylic acid
-drop the -oic
-add -oate
ie) butanoic acid would become butanoate
• (drawings on white board)
Drawing Rules
• Drawing esters combines drawing Alcohols
and drawing Carboxylic Acids.
O
OH
Butanoic Acid
+
OH
Ethanol
O
+

H-OH
O
Ethyl Butanoate
• The alkyl with the –oate is double bonded to
an oxygen atom. The alkyl with the –yl has an
oxygen atom incorporated in it.
Physical and Chemical Properties
•
•
•
•
Low polarity
Not as polar as alcohols
Dipole-Dipole, London dispersion
In Hydrogen bond, esters can only act as
Hydrogen acceptors, not donors
• Unsaturated fats/oils always have at least one
C=C double bond
• Similar boiling points to ketones and
Aldehydes
• As chain length increases, solubility in water
decreases
• Solid form: Fat
• Liquid form: Oil
• Fats have a higher boiling point
Uses
• Esters are known for the odours of fruits, flowers,
cosmetics and perfumes.
• Esters are also used in fats and oils.
• Synthetic esters are added as flavourings to
processed foods.
• They are good compounds for polar organic
compounds like; printing ink and cement.
Examples
• Apple- methyl butanoate
CH3CH2CH2COOCH3
• Banana- 3-methylbutyl ethanoate
CH3
|
CH3COOCH2CH2CHCH3
• Cherry- ethyl benzoate
C6H5COOC2H5
• Pineapple- ethyl butanoate
CH3CH2CH2COOCH2CH3
• Rum- ethyl methanoate
CH3CH22CH2CH2CH2CH2COOCH2CH3
Reactions: Esterification
• Neutralization/condensation reaction
heat
carboxylic acid + alcohol ---------->
ester + water
catalyst
organic base
O
organic salt
O
||
heat
|| – OH + R–OH -------->
RC–O–R
+
HOH
catalyst
RC
Reactions: Hydrolysis
• Ester treated with acid or base: reversal of
esterification occurs (split into acid & alcohol)
• Products: sodium salt of acid + alcohol
O
O
||
||
RC–O–R + NaOH- ------> RC–O- + Na+ + R–OH
ester
base
acid
alcohol
Reactions: Saponification
• Fats and oils are esters of long-chain acids:
• When heated with a strong base,
saponification occurs & produces soap.
References
AUS-e-TUTE. (n.d.) Chemistry Tutorial: Esters and Esterification. Retrieved from
the Web 29/09/11. http://www.ausetute.com.au/esters.html
Clark, J. (2004). Introducing Esters. Retrieved from the Web 22/09/11.
http://www.chemguide.co.uk/organicprops/esters/background.html
Kimble, M.G. (2008). Esterification Reactions. Retrieved from the Web 29/09/11.
http://www.ipfw.edu/chem/112/kimble/5-Synthesis%20of%20Esters.pdf
Snelling, C.R. (2002). Synthesis of an Ester: Fischer Esterification. Retrieved from
the Web 29/09/11. http://www2.volstate.edu/msd/CHE/242/Labs/Ester.htm
van Kessel, H., Jenkins, F., Davies, L., Plumb, D., Di Giuseppe, M., Lantz, O., &
Tompkins, D. (2003). Nelson Chemistry 12. Toronto: Nelson Thomson Canada
Limited.