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13C NMR Interpretation

13C NMR Shift Values

Question 1

• A compound has a molecular formula of C5H8O2 and exhibits the following 13C NMR spectrum; �; 199.83, 197.54, 29.22, 23.70, 6.95. Which of the compounds listed below would be consistent with this structure?

• Hint #1: Count the number of peaks– 5 peaks

Question 1 Answer Set

Step 1: Narrow the list of possibilities with the number of possible peaks

Question 1 Answer Set

3 peaks

3 peaks

Question 1 Answer Set

Step 2: What should the 13C NMR spectrum look like?

Choice 1

171.42

69.47

29.84

22.31

19.06

Choice 2

166.18

130.31

128.88

60.48

14.28

Choice 3

170.67

132.50

118.0965.19

20.81

Choice 4

27.72

197.21

106.85

163.49

57.54

Choice 5

171.48

141.42

97.34

27.33

8.80

Choice 6

199.83

197.54

23.70

29.22

6.95

Question 1 Answer Set

Final step: The choice looking most similar to expectations

Question 2

• A compound exhibits the following 13C NMR spectrum: �; 171.42, 69.47, 29.84, 22.31, 19.06Which of the compounds listed below would be consistent with this structure?

• Hint #1: Count the number of peaks– 5 peaks

Question 2 Answer Set

Step 1: Narrow the list of possibilities with the number of possible peaks

Question 2 Answer Set

4 peaks

4 peaks3 peaks

3 peaks

Reconfirm your choice with expectations

171.42

69.47

29.84

22.31

19.06

Question 2 Answer Set

Question 3

• A compound has a molecular formula of C8H10 and exhibits the following 13C NMR spectrum; �; 136.42, 129.63, 125.85, 19.66 . Which of the compounds listed below would be consistent with this structure?

• Hint #1: Count the number of peaks– 4 peaks

Question 3 Answer Set

Step 1: Narrow the list of possibilities with the number of possible peaks

Question 3 Answer Set

Step 1: Narrow the list of possibilities with the number of possible peaks

6 peaks

3 peaks5 peaks

Question 3 Choice 1

64.89

78.69

13.01

13.53

Mirror plane

Question 3 Choice 2

125.85

129.63

136.4219.66

Mirror plane

Question 3 Answer Set

Step 1: Narrow the list of possibilities with the number of possible peaks