Question

Explain the following:

a) Define Esterification.
b) Write any three uses of ethanol.

Answer 1

Hint: Esterification is generally carried out on carboxylic acids and turns it into ether which is an organic compound, in presence of alcohol. Ethers are organic compounds containing an alkoxy functional group.

Ethanol is an alcohol and contains (–OH) functional group and is used in various reactions. In ethanol, a carbon of the methyl group is attached to a carbon of the methylene group and the same carbon of the methylene group is attached to the hydroxyl group.

Complete answer:

At first, we will discuss about esterification:

Esterification is the process of converting the two reactants (an alcohol and an acid) into an ester as the product. Ester is a chemical compound derived from an acid having a hydroxyl (-OH) group which is converted into alkoxy (-O-alkyl) group and the process of conversion is called esterification.

Usually substitution reaction of carboxylic acid and an acid gives ester. We can write the reaction as:
\[\begin{align}
  & RC{{O}_{2}}H+{{R}^{'}}OH\rightleftharpoons RC{{O}_{2}}{{R}^{'}}+{{H}_{2}}O \\
 & carboxylic+alcohol\rightleftharpoons ester+water \\
 & acid \\
\end{align}\]

This reaction is slow if no catalyst is used. Therefore, sulphuric acid is used as a catalyst here.

As esterification is reversible we can take the following steps to improve the yield of the product:
- Using excess alcohol
- Using sulphuric acid which acts as a catalyst and also a dehydrating agent.
- Removing water by distillation.
Esters have a fruity, pleasant smell and are used in the fragrance and food industry.

Now we will discuss the uses of ethanol:
Ethanol is also known as ethyl alcohol and its chemical formula is ${{C}_{2}}{{H}_{5}}OH$. It is a volatile and flammable liquid and it has a colourless appearance and a characteristic odour. It has various medicinal, fuel and chemical advantages. Uses of ethanol are:

- Ethanol is used as antiseptic and is the most commonly used in hand sanitizers and medicinal wipes for its antibacterial effects. It kills microorganisms like bacteria, fungi by dissolving their membrane lipid bilayer and by denaturing their proteins.

- Ethanol is also used as an engine fuel and fuel additive particularly in Brazil. Gasoline sold in Brazil contains around 26% anhydrous ethanol.

- Ethanol is used as a universal solvent because its molecular structure allows dissolving of both- polar and nonpolar as well as hydrophobic and hydrophilic compounds.

Additional Information:
Esterification can also be carried out by using epoxides or acid anhydrides with carboxylic acid instead of alcohol and also by alkylation of carboxylic acid.

Note:
Esterification is a slow reaction therefore it needs a catalyst for better and faster yield. Esterification is the method by which an acid is converted into ether.
Ethanol is an alcohol and its physical properties are a result of shortness of the carbon chain and the presence of hydroxyl groups.