What are Esters???

Definition of Esters and Esterification:

Ester is an organic compound formed when an alcohol reacts with a carboxylic acid.

Esters are produced during the Esterification Process.

Esterification Process - Alcohols and carboxylic acids react in the presence of concentrated sulphuric acid to form esters. (Sulphuric acid acts a catalyst to produce esters)

Acid + Alcohol = Ester + Water( this reaction is esterification)
E.g:Ethanoic acid + Ethanol = Ethyl Ethanoate + Water
CH3COOH(l) + C2H5OH(l) = CH3COOC2H5(l) + H2O(l)

Ester Preparation( in small quantities) :
E.g: Butyl Ethanoate

1. Mix Butanol ( the alcohol), Ethanoic acid (carboxylic acid) and Sulphuric acid and heat it in a waterbath.
   
2. When poured into a beaker of water, the ester forms a colourless layer on top of the water.

How to identify Esters?

As the background of our blog suggests, esters are sweet- smelling substances just like roses and any other flowers..

Characteristics of Esters:

• Sweet- smelling
• Colourless liquids
• Insoluble in water
• Good Solvents for other compounds
• have low boiling points

Esters can be divided into 2 categories: 1) Natural
2) Synthetic

Natural Esters: Fruits contain natural esters.Strong , sweet smell from bananas, pineapples, other fruits due to presence of esters. Each ester owns characteristic smell.
E.g:

1) Ethyl Methanoate => H-CO₂-CH₂-CH_{3 => Rum
2)} Methyl Phenyl Ethanoate => C₆H₅-CH₂-CO₂-CH_{3 =>} Honey
3) Benzyl Ethanoate => C₆H₅-CH₂-CO₂CH_{3 =>} Jasmine
4) Pentyl Ethanoate => CH₃-CO₂-CH₂-CH₂-CH₂-CH₂-CH_{3 =>} Pear
5) 3-Methylbutyl Ethanoate => CH₃-CO₂-CH₂-CH₂-CH(CH₃)-CH_{3 =>} Banana
6) Octyl Ethanoate=> CH₃-CO₂-CH₂(CH₂)₆-CH_{3 =>} Orange
7) Methyl Butanoate=> CH₃-CH₂-CH₂-CO₂-CH_{3 =>} Pineapple
8) Ethyl Butanoate => CH₃-CH₂-CH₂-CO₂CH₂CH_{3 =>} Peach
9) 3-Methylbutyl-3-Methylbutanoate => CH₃CH(CH₃)CH₂CO₂CH₂CH₂CH(CH₃)CH₃=>Apple
10) Pentyl Butanoate=> CH₃-CH₂-CH₂CO₂-CH₂-(CH₂)₃-CH_{3 =>} Apricot

Synthetic Esters: Artificial fruit flavours in foods. Fruity flavours for foods and drinks such as milkshakes, ice-cream, chewing gum, jellies, sweets and cakes.



Other uses of Esters: Used as solvents for glues, perfumes, nail polish remover and paints.


Naming Esters : ' -yl' represents alcohol
'- oate' represents acid

E.g: Methyl Ethanoate- Methanol and Ethanoic acid

Butanoic acid + Ethanol => Ethyl Butanoate (artificial pineapple flavouring) + Water