Rank each set of compounds in order of decreasing λ_max:

a.

Rank each set of compounds in order of decreasing λ_max:

b.

At pH = 7, one of the ions shown here is purple and the other is blue. Which is which?

What would be the difference in the colors of the compounds at pH = 3?

In the mass spectrum of the following compounds, which is the tallest—the peak at m/z = 57 or the peak at m/z = 71?

a. 3-methylpentane

b. 2-methylpentane

Rank the following compounds in order of increasing lmax:

For each of the following pairs of compounds, identify one IR absorption band that could be used to distinguish between them:

c. CH₃CH₂CH₂OH and CH₃CH₂OCH₃

d.

For each of the following pairs of compounds, identify one IR absorption band that could be used to distinguish between them:

i.

j.

a. How could you use IR spectroscopy to determine whether the following reaction had occurred?

b. After purifying the product, how could you determine whether all the NH₂NH₂ had been removed?

Assuming that the force constant is approximately the same for C–C, C–N, and C–O bonds, predict the relative positions of their stretching vibrations in an IR spectrum.

Norlutin and Enovid are ketones that suppress ovulation, so they have been used clinically as contraceptives. For which of these compounds would you expect the infrared carbonyl absorption (C=O stretch) to be at a higher frequency? Explain.

A mass spectrum shows significant peaks at m/z = 87, 115, 140, and 143. Which of the following compounds is responsible for that mass spectrum?

A compound gives a mass spectrum with essentially only three peaks at m/z = 77 (40%), 112 (100%), and 114 (33%). Identify the compound.

What hydrocarbons that contain a six-membered ring will have a molecular ion peak at m/z = 112?

Rank the following compounds from highest wavenumber to lowest wavenumber for their C=O absorption band:

Rank the following compounds from highest wavenumber to lowest wavenumber for their C-O absorption band:

The mass spectrum for a compound with molecular weight of 102 is shown below. Its IR spectrum has a broad, strong absorption at 3600 cm^–1 and a medium absorption at 1360 cm^–1.

a. Identify the compound.

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The mass spectrum for a compound with molecular weight of 102 is shown below. Its IR spectrum has a broad, strong absorption at 3600 cm^–1 and a medium absorption at 1360 cm^–1.

b. Show the mechanism for formation of the peak at m/z = 84.

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Which one of the following five compounds produced the IR spectrum shown below?

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The IR spectrum of compound A with a molecular formula of C₅H₁₂O is shown below. Compound A is oxidized to give compound B, a ketone with a molecular formula of C₅H₁₀O. When compound A is heated with H2SO4, compounds C and D are obtained. Considerably more D is obtained than C. Reaction of compound C with O₃, followed by treatment with dimethyl sulfide, gives two products: formaldehyde and compound E, with a molecular formula of C₄H₈O. Reaction of compound D with O₃, followed by treatment with dimethyl sulfide, gives two products: compound F, with a molecular formula of C₃H₆O, and compound G, with a molecular formula of C₂H₄O. What are the structures of compounds A through G?

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Each of the IR spectra shown below is accompanied by a set of four compounds. In each case, indicate which of the four compounds is responsible for the spectrum.

a.

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Five compounds are shown for each of the IR spectra below. Indicate which of the five compounds is responsible for each spectrum.

c.

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How can IR spectroscopy distinguish between 1-hexyne, 2-hexyne, and 3-hexyne?

Give approximate wavenumbers for the major characteristic IR absorption bands that would be given by each of the following compounds:

a.

b.

Give approximate wavenumbers for the major characteristic IR absorption bands that would be given by each of the following compounds:

e.

f.

Phenolphthalein is an acid–base indicator. In solutions of pH < 8.5, it is colorless; in solutions of pH > 8.5, it is deep red-purple. Account for the change in color.

Each of the IR spectra shown below is the spectrum of one of the following compounds. Identify the compound that produced each spectrum.

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Each of the IR spectra shown below is the spectrum of one of the following compounds. Identify the compound that produced each spectrum.

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How can you use UV spectroscopy to distinguish between the compounds in each of the following pairs?

a.

How can you use UV spectroscopy to distinguish between the compounds in each of the following pairs?

b.