Lecture 5 – Esters

ACKNOWLEDGEMENT:

Figure	Source of Figure
Figure 19	http://www.bbc.co.uk
Figure 20	study.com
Figure Table 8a	http://commons.wikimedia.org/
Figure Table 8b	http://commons.wikimedia.org/
Figure Table 8c	http://janison.cyriljackson.wa.edu.au/
Figure Table 8d	http://www.ivyroses.com/
Figure Table 8e	-
Figure Table 8f	http://imgarcade.com/
Figure Table 8g	http://www.gcsescience.com/
Figure Table 8h	http://www.ivyroses.com/

Esters:

Esters are formed as a product of the reaction between alcohols and carboxylic acids, in the presence of concentrated sulphuric acid as a catalyst. Water is released as a by-product of this reaction.

Figure 19 shows the reaction:

Figure 19:

The H radical from the alcohol and the Hydroxyl; -OH radical from the acid combine to form water.

The ester is bonded by the ester linkage which is bonded by the ester linkage.

Figure 20:

  

Since, 2 reactants condense to form a single compound and release water as a by-product, this is also known as Condensation Polymerization. 

Naming convention of Esters:

Consider the following table.

Table 8: 

Ester	Chemical Formula	Structure
Methyl Methanoate	HCOOCH3
Methyl Ethanoate	CH3COOCH3
Methyl Propanoate	C2H5COOCH3
Methyl Butanoate	C3H7COOCH3
Ethyl Methanoate	HCOOC2H5
Ethyl Ethanoate	CH3COOC2H5
Ethyl Propanoate	C2H5COOC2H5
Ethyl Butanoate	C3H7COOC2H5

Note the following 2 points:

1. The structure read from left to right shows that the acidic portion of the ester first, followed by the – COO – bond, and then the alcohol portion.
2. In the naming convention, the alcohol name comes first, followed by the name of the acid used, ending with –ate.

Industrial uses of Esters:

Esters are sweet smelling compounds. They, thus have a large variety of industrial uses such as:

1. Artificial flavourings in food industry
2. Scents in perfume industry
3. As a solvent