Question

Define the term fatty acids. Give the common and IUPAC names for the following fatty acids
1) ${\text{C}}{{\text{H}}_{\text{3}}}{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)_{{\text{14}}}}{\text{COOH}}$
2) ${\text{C}}{{\text{H}}_{\text{3}}}{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)_{{\text{16}}}}{\text{COOH}}$
3) ${\text{C}}{{\text{H}}_{\text{3}}}{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)_{\text{7}}}{\text{CH}} = {\text{CH}}{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)_{\text{7}}}{\text{COOH}}$

Answer 1

Hint:We know that fatty acids are important components of lipids in plants, animals and microorganisms. Naturally occurring fatty acids have an unbranched chain of even numbers of carbon atoms ranging from 4 to 28. Fatty acids are the main constituent of fat soluble components of living cells.


Complete solution:
Fatty acids are building blocks of fat in the body and the food we eat. During digestion, fats are broken down to fatty acids which are then absorbed by blood. Three fatty acid molecules are joined together and result in formation of a triglyceride.
Fatty acids are defined as carboxylic acids which consist of a hydrocarbon chain and a terminal carboxyl group. The fatty acids can be saturated or unsaturated.
In the IUPAC nomenclature of fatty acids, fatty acids have an –oic acid suffix. While writing common names, -ic is used as a suffix.
Fatty acids are named depending on the number of carbon atoms and carbon-carbon double bonds.
We are given three fatty acids as follows:
1) ${\text{C}}{{\text{H}}_{\text{3}}}{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)_{{\text{14}}}}{\text{COOH}}$: The total number of carbon atoms is 16. Thus, the IUPAC name of the acid is hexadecanoic acid. The common name is palmitic acid.
2) ${\text{C}}{{\text{H}}_{\text{3}}}{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)_{{\text{16}}}}{\text{COOH}}$: The total number of carbon atoms is 18. Thus, the IUPAC name of the acid is octadecanoic acid. The common name is stearic acid.
3) ${\text{C}}{{\text{H}}_{\text{3}}}{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)_{\text{7}}}{\text{CH}} = {\text{CH}}{\left( {{\text{C}}{{\text{H}}_{\text{2}}}} \right)_{\text{7}}}{\text{COOH}}$: The total number of carbon atoms is 18. The carbon-carbon double bond is at carbon number 9. Thus, the IUPAC name of the acid is 9-octadecenoic acid. The common name is oleic acid.


Note: Foods that contain fatty acids are fish, sea food, nuts, flaxseed, chia seeds, walnuts, flaxseed oil, soybean oil, canola oil, etc. fatty acids are obtained by hydrolysis of naturally occurring fats and oils. Fatty acids have an important part in the composition of hormones and lipids and in the modification of proteins.