15. Analytical Techniques:IR, NMR, Mass Spect

Would it be better to use ¹H NMR or ¹³C NMR spectroscopy to distinguish 1-butene, cis-2-butene, and 2-methylpropene? Explain your answer.

Identify the compound with molecular formula C₇H₁₄O that gives the following proton-coupled ¹³C NMR spectrum:

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An inexperienced graduate student was making some 4-hydroxybutanoic acid. He obtained an excellent yield of a different compound, whose ¹³C NMR spectrum is shown here.

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(a) Propose a structure for this product.

(b) Assign the peaks in the ¹³C NMR spectrum to the carbon atoms in the structure.

Draw the ¹³C NMR spectrum of each molecule in Assessment 15.48.

(b)

Identify each compound below from its molecular formula and its ¹³C NMR spectrum.

a. C₁₁H₂₂O

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How many signals are produced by each of the following compounds in its

b. ¹³C NMR spectrum?

6.

How many signals are produced by each of the following compounds in its

b. ¹³C NMR spectrum?

5.

Sketch the following spectra that would be obtained for 2-chloroethanol:

e. The four parts of a DEPT ¹³C NMR spectrum.

How many signals would you expect to see in the 13C NMR of the following compounds? In each case, show which carbon atoms are equivalent in the ¹³C NMR.

How many signals are produced by each of the following compounds in its

b. ¹³C NMR spectrum?

1.

Draw the ¹³C NMR spectrum you would expect to see for each of the molecules shown.

(c)

Describe the proton-coupled ¹³C NMR spectra for compound 1 in Problem 41, indicating the relative positions of the signals.

1. CH₃CH₂CH₂Br

How can 1,2-, 1,3-, and 1,4-dinitrobenzene be distinguished by

b. ¹³C NMR spectroscopy?

(a) Show which carbon atoms correspond with which peaks in the 13C NMR spectrum of butan-2-one (Figure 13-45).

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Answer the following questions for each compound:

a. How many signals are in its ¹³C NMR spectrum?

b. Which signal is at the lowest frequency?

8.