Question

\(\beta\)-Ocimene, a triene found in the fragrance of cotton blossoms and several essential oils, has the IUPAC name \((Z)-3,7\)-dimethyl- \(1,3,6\)-octatriene. Draw a structural formula for \(\beta\)-ocimene.

Short answer

Answer: The structural formula for β-ocimene is H2C=C(CH3)C=C(CH3)C=CHCH2CH3.

Step-by-step solution

Draw the 8-carbon backbone

Draw a straight chain of 8 carbon atoms for the oct- part of the IUPAC name.

Add the double bonds

Add double bonds between carbon atoms according to the 1,3,6-octatriene part of the name, giving us a molecule with double bonds at positions 1, 3, and 6. Remember that the numbering starts from one end of the chain, so you will have a double bond at the first and second carbon, then at the third and fourth, and finally between the sixth and seventh carbon atoms.

Determine and assign the (Z)- geometry

Look at the double bond with the subscript (Z), which stands for the cis- configuration between the two carbon atoms involved in the double bond. In this case, it refers to the double bond between carbons 3 and 4. The (Z)- geometry means that the two higher-priority substituents on both ends of that double bond should be on the same side. The higher-priority substituent will be the part of the molecule connected to the double bonded carbon, which is not a hydrogen atom.

Add the methyl groups

Finally, add the two methyl groups to the carbon atoms at positions 3 and 7, as indicated by the IUPAC name 3,7-dimethyl. The drawn structural formula of β-ocimene should look like the following: ``` H2C=C(CH3)C=C(CH3)C=CHCH2CH3 ```