How many peaks are there in the 13C NMR spectrum of 1,4-dimethylbenzene?
A 8
B 4
C 3
D 2 - AQA - A-Level Chemistry - Question 16 - 2018 - Paper 3
Question 16
How many peaks are there in the 13C NMR spectrum of 1,4-dimethylbenzene?
A 8
B 4
C 3
D 2
Worked Solution & Example Answer:How many peaks are there in the 13C NMR spectrum of 1,4-dimethylbenzene?
A 8
B 4
C 3
D 2 - AQA - A-Level Chemistry - Question 16 - 2018 - Paper 3
Step 1
Determine the number of unique carbon environments
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Answer
In 1,4-dimethylbenzene, the molecule has a symmetrical structure. The two methyl groups are on opposite sides of the benzene ring, which means each methyl group (C) is identical. Therefore, there are unique carbon environments: one for the benzene ring and one for each methyl group.
Step 2
Count carbon environments
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Answer
In total, we find:
4 carbons in the benzene ring (only 2 are unique due to symmetry),
2 unique methyl carbons.
Thus, we end up with a total of 4 unique carbon environments.
Step 3
Conclude the answer
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Answer
In summary, the answer to how many peaks will be observed in the 13C NMR spectrum of 1,4-dimethylbenzene is 4, corresponding to option B.
