Question

In carbinol system isobutyl alcohol is named as

• A. Ethyl methyl carbinol
• B. Isobutyl carbinol
• C. Isopropyl carbinol
• D. Diethyl carbinol

Hint:

To easily use the carbinol system on any structure, draw the molecule and draw a circle strictly around the -C-OH group (including its attached hydrogens). Whatever alkyl chain is left outside your circle is your prefix name. For isobutyl alcohol, an isopropyl group remains outside the circle.

Answer 1

The Correct Option is C

Step 1: Understand the question.
We must name isobutyl alcohol using the old carbinol system.

Step 2: Recall the carbinol system.
In this system methanol, $\text{CH}_3\text{OH}$, is the base called carbinol. The carbon carrying the -OH is the carbinol carbon. Groups joined to that carbon are named in front.

Step 3: Write the structure of isobutyl alcohol.
\[ (\text{CH}_3)_2\text{CH}\text{-CH}_2\text{-OH} \]

Step 4: Find the carbinol carbon.
The terminal $\text{-CH}_2\text{OH}$ is the carbinol core. Whatever is attached to it becomes the substituent name.

Step 5: Name the attached group.
The group joined to the carbinol carbon is $(\text{CH}_3)_2\text{CH-}$, which is the isopropyl group.

Step 6: Combine and choose.
Joining the substituent to carbinol gives isopropyl carbinol, which is option 3.
\[ \boxed{\text{Isopropyl carbinol}} \]