What is the relationship between 2-methyl-3-chloropentane and 2-chloro-3-methylbutane? A) Enantiomers B) Diastereomers C) Structural isomers D) Not isomers E) They are identical
The correct answer and explanation is:
Correct Answer: C) Structural isomers
Explanation (300 words):
To determine the relationship between 2-methyl-3-chloropentane and 2-chloro-3-methylbutane, we need to analyze their structures and molecular formulas.
1. Analyzing 2-methyl-3-chloropentane:
- The parent chain is pentane (5 carbon atoms).
- At carbon 2, there is a methyl group (-CH₃).
- At carbon 3, there is a chlorine atom (-Cl).
Structure:
CH3
|
CH3–CH–CH–CH2–CH3
|
Cl
This gives a total of 6 carbon atoms, and one chlorine atom.
2. Analyzing 2-chloro-3-methylbutane:
- The parent chain is butane (4 carbon atoms).
- At carbon 2, there is a chlorine atom (-Cl).
- At carbon 3, there is a methyl group (-CH₃).
Structure:
CH3
|
CH3–CH–CH–CH3
|
Cl
This also gives a total of 6 carbon atoms, and one chlorine atom.
3. Conclusion:
- Both compounds have the same molecular formula: C₆H₁₃Cl.
- However, their connectivity of atoms is different:
- In 2-methyl-3-chloropentane, the main chain is pentane with a methyl and chlorine on different carbons.
- In 2-chloro-3-methylbutane, the main chain is butane, and the substituents are positioned differently.
Since the arrangement of atoms is different but the molecular formula is the same, these two compounds are structural isomers (also known as constitutional isomers).
They are not stereoisomers (like enantiomers or diastereomers) because their atom connectivity is not the same to begin with.