What is the IUPAC name for the molecule shown below?
A) 5,6,6-trimethyl-1-heptyne
B) 5-tert-butyl-1-hexyne
C) 2,2,3-trimethyl-6-heptyne
D) 2,2,3-(3-butynyl)butane
E) sec-butyl-tert-butylacetylene
What is the IUPAC name for the molecule shown below?
A) 4,4-dimethyl-2-pentyne
B) 2,2-dimethyl-4-heptyne
C) 1-tert-butyl-3-heptyne
D) 6,6-dimethyl-3-heptyne
E) 6,6,6-trimethyl-3-hexyne
The Correct Answer and Explanation is :
The IUPAC names for the two molecules are as follows:
1. First Molecule:
The correct IUPAC name is 5-tert-butyl-1-hexyne.
Explanation:
- Longest Carbon Chain: The molecule contains a six-carbon chain with a triple bond between the first and second carbons, indicating it is a hexyne.
- Substituents: A tert-butyl group (–C(C₆H₁₁)₃) is attached to the fifth carbon of the chain.
- Numbering: The chain is numbered from the end nearest the triple bond to give the lowest possible locants to the triple bond and substituents.
Therefore, the IUPAC name is 5-tert-butyl-1-hexyne.
2. Second Molecule:
The correct IUPAC name is 4,4-dimethyl-2-pentyne.
Explanation:
- Longest Carbon Chain: The molecule has a five-carbon chain with a triple bond between the second and third carbons, indicating it is a pentyne.
- Substituents: Two methyl groups (–CH₃) are attached to the fourth carbon of the chain.
- Numbering: The chain is numbered from the end nearest the triple bond to give the lowest possible locants to the triple bond and substituents.
Therefore, the IUPAC name is 4,4-dimethyl-2-pentyne.
These names are consistent with the IUPAC nomenclature rules for organic compounds.