15. Analytical Techniques:IR, NMR, Mass Spect

A bottle of allyl bromide was found to contain a large amount of an impurity. A careful distillation separated the impurity, which has the molecular formula C₃H₆O. The following ¹³C NMR spectrum of the impurity was obtained:

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(a) Propose a structure for this impurity.

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

(c) Suggest how this impurity arose in the allyl bromide sample.

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

(c)

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

(a)

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

(b)

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

d. The proton-coupled ¹³C NMR spectrum.

Assign each signal in the ¹³C NMR spectra to the molecule shown.

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

b. ¹³C NMR spectrum?

4.

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?

9. CH₂=CHBr

Describe the proton-coupled ¹³C NMR spectra for compound 5 in Problem 41, indicating the relative positions of the signals.

5.

Different types of protons and carbons in alkanes tend to absorb at similar chemical shifts, making structure determination difficult. Explain how the ¹³C NMR spectrum, including the DEPT technique, would allow you to distinguish among the following four isomers.

Identify the compound with molecular formula C₆H₁₀O that gives the following DEPT ¹³C NMR spectrum:

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The standard ¹³C NMR spectrum of phenyl propanoate is shown here. Predict the appearance of the DEPT-90 and DEPT-135 spectra.

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

(a)