Question

In the \( ^1H \) NMR spectrum, which one of the following compounds will show a triplet? 

 

• A. (A)
• B. (B)
• C. (C)
• D. (D)

Hint:

In \( ^1H \) NMR, a triplet occurs when a proton is coupled to two equivalent neighboring protons.

Answer 1

The Correct Option is A

Step 1: Understanding the concept of splitting in \( ^1H \) NMR. 
In \( ^1H \) NMR, the splitting pattern is determined by the number of adjacent protons (coupling). A triplet occurs when a proton is coupled to two equivalent protons. This will split the signal into three peaks (a triplet), with the coupling constant (\( J \)) determining the spacing between the peaks. 
 

Step 2: Analyzing the compounds. 
- **(A)** The compound shows a methylene group (\( CH_2 \)) next to a \( CH_3 \) group, which will split the signal into a triplet. 

- **(B)** This compound shows two equivalent methyl groups (\( CH_3 \)) attached to a carbonyl group, which will not show a triplet. 

- **(C)** This compound has a benzene ring and a methyl group, but no adjacent equivalent protons that would cause a triplet. 

- **(D)** This compound has a hydroxyl group and a bromine atom attached to the benzene ring, but no protons that would create a triplet pattern. 
 

Step 3: Conclusion. 
The correct answer is (A), as it is the only compound that will show a triplet in its \( ^1H \) NMR spectrum.