Textbook Problem

In omega-3 fatty adds, the last carbon of the last double bond of the hydrocarbon chain ends three carbons from the methyl terminal end of the chain. The last carbon of the chain is called the omega carbon, hence, the designation omega-3. Eicosapentae- noic acid is a common omega-3 fatty acid found in cold water fatty fish and health food supplements.

CH₃(CH₂CH=CH )₅CH₂CH₂CH₂CO₂H

Eicosapentaenoic acid

a C₂₀ polyunsaturated fatty acid

1. How many cis-trans isomers are possible for this fatty acid?
2. Draw a line-angle formula for eicosapentaenoic acid, showing the cis configuration of all carbon- carbon double bonds in the hydrocarbon chain.