Write Lewis structures and IUPAC names for the alkyne isomers of C4H6.
The correct answer and explanation is :
The molecular formula (C_4H_6) represents a compound that can have multiple alkyne isomers. Alkyne molecules contain at least one carbon-carbon triple bond. To identify and name the alkyne isomers, let’s consider the possible structural variations.
Alkyne Isomers of (C_4H_6):
- Butyne (1-butyne)
- Structure:
[
\text{CH}_3\text{C}\equiv\text{C}\text{CH}_3
] - IUPAC Name: 1-Butyne
- Lewis Structure:
- The structure consists of a four-carbon chain with a triple bond between the first and second carbon atoms. The remaining bonds are single bonds, with hydrogen atoms filling the necessary valence requirements.
- Explanation: In this compound, both methyl groups ((\text{CH}_3)) are attached to the carbons involved in the triple bond. The triple bond ensures the molecule follows the alkyne functional group.
- 2-Butyne
- Structure:
[
\text{CH}_3\text{C}\equiv\text{C}\text{H}
] - IUPAC Name: 2-Butyne
- Lewis Structure:
- The structure consists of a four-carbon chain with the triple bond between the second and third carbon atoms. One methyl group ((\text{CH}_3)) is attached to the first carbon, and a single hydrogen atom is bonded to the fourth carbon.
- Explanation: The carbon atoms adjacent to the triple bond are involved in single bonds with hydrogen atoms, while the molecule maintains the triple bond between the second and third carbons.
Explanation:
The IUPAC system of naming alkynes follows the rule of identifying the longest carbon chain that contains the triple bond. In these cases, both isomers have a four-carbon chain, but their structural arrangement around the triple bond differs, leading to different names.
- 1-Butyne is the simpler case where the triple bond is at the end of the carbon chain, whereas 2-butyne has the triple bond in the middle of the chain. This difference in the position of the triple bond is crucial in determining their IUPAC names.
Both compounds are examples of alkynes, characterized by the presence of a carbon-carbon triple bond, and they follow the general formula for alkynes: (C_nH_{2n-2}).
Conclusion:
In total, the two alkyne isomers of (C_4H_6) are 1-butyne and 2-butyne, differing by the position of the triple bond along the carbon chain.