Which of the following structures represents 4-methylcyclohexanol? H3C OH H3C CH3 H3C OH CH3
The Correct Answer and Explanation is:
Correct Answer: The correct structure of 4-methylcyclohexanol is:
A cyclohexane ring with a hydroxyl group (OH) attached to carbon 1 and a methyl group (CH₃) attached to carbon 4.
Explanation:
To determine the correct structure of 4-methylcyclohexanol, you must understand both the numbering of the cyclohexane ring and the placement of substituents on that ring.
1. Base structure: Cyclohexanol
- Cyclohexanol is a six-carbon ring (cyclohexane) with one hydroxyl group (-OH) attached.
- When numbering the ring, the carbon attached to the OH group is always numbered as carbon 1 because OH has higher priority in IUPAC naming rules.
2. Methyl group placement
- The “4-methyl” part means there is a methyl group (CH₃) attached to carbon 4 of the ring.
- You must number the ring in the direction that gives the next substituent (the methyl group) the lowest possible number after assigning 1 to the OH group.
3. Putting it together
- Start with cyclohexane.
- Attach an OH group to carbon 1.
- Then, counting three carbons away (in either direction), attach a methyl group to carbon 4.
So the structure will look like this:
yamlCopyEdit CH3
|
C6—C1—C2
/ \
C5 C3
\ /
C4———C
|
OH
Alternatively, in skeletal or line structure diagrams, the ring will appear as a hexagon. One carbon will have an OH sticking out, and the carbon directly across the ring (carbon 4) will have a CH₃ group.
This structure satisfies the name 4-methylcyclohexanol, because it has:
- A six-membered ring (cyclohexane)
- An OH on carbon 1
- A CH₃ on carbon 4
None of the choices like “H₃C OH H₃C CH₃” or “H₃C OH CH₃” accurately depict this unless shown as part of a ring structure. The correct answer must include a ring with these proper attachments.
