Esters are formed through an esterification reaction when a carboxylic acid reacts with an alcohol in the presence of a concentrated sulfuric acid catalyst. Esters have various physical properties including being colorless liquids at room temperature with sweet, pleasant smells and low boiling points and densities. They are found naturally in many plants and fruits where they contribute to smells and flavors. Esters have several applications including use as food flavorings, in cosmetics, fragrances, and medicines.

1. General formula:
m = 0, 1, 2, 3...
n = 1, 2, 3...
Functional group:
Naming of Ester
CnH2n+1COOCmH2m+1
Carboxylate group ( -COO- )
Molecular
formula HCOOCH3 CH3COOCH3 CH3COOC2H5 C2H5COO C2H5
Name
Methyl
methanoate
(m=0, n=1)
Ethyl
methanoate
(m=1, n=1)
Ethyl
ethanoate
(m=1, n=2)
Propyl
ethanoate
(m=2, n=2)
Esters

2. Physical
Properties
of Ester
State
- Simple ester is
colourless liquid at
room condition
Odour
- Sweet pleasant smell
(fruity smell)
Boiling point
- low boiling point
Density
- Low density
Solubility
- Slightly soluble in
water but readily
dissolve in organic
solvent

3.  Esters are produced when carboxylic acid
reacts with alcohol in the presence of
concentrated sulphuric acid as a catalyst.
 This reaction is called the esterification
reaction.
• Catalyst: Concentrated H2SO4
 Example:
Formation of Ester

4. Natural Sources
 Ester can be found naturally in plants.
 Most of natural esters exist in plants and
animals in the form of oil and fats such as
coconut oil, palm oil, olive oil, vegetable oil,
cow fat and goat fat.
 Fruit
• Pineapple – C3H7COOC2H5
Ethyl butanoate
 Flower
• Jasmine – CH3COOCH2C6H5
Benzyl ethanoate

5.  As food flavourings
• Food such as cakes, ice cream, sweets and soft
drinks contains ester
 To make cosmetics
• Volatility property of esters makes it suitable for
making perfumes
 As a fragrant
• Used in substances such as soaps, powder and
detergents
 To make medicine
• Used to make medicine for treatment of disease
such as leprosy and asthma
Use of Esters