15. Analytical Techniques:IR, NMR, Mass Spect

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

a.

b.

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:

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

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?

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

i.

j.

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, name one absorption band that can be used to distinguish between them.

c.

d.

How can IR spectroscopy be used to distinguish between the following compounds?

e. cyclohexene and cyclohexane

f. a primary amine and a tertiary amine

How can IR spectroscopy be used to distinguish between the following compounds?

a. a ketone and an aldehyde

b. a cyclic ketone and an open-chain ketone

A nitrogen-containing compound shows no absorption band at ~3400 cm^-1 and no absorption bands between ~1700 cm^-1 and ~1600 cm^-1 or between 2260 cm^-1 and 2220 cm^-1. What class of compound is it?

Identify the important bands you would expect to find in an IR spectrum for the following molecules.

(a)

Identify the important bands you would expect to find in an IR spectrum for the following molecules.

(c)

A carboxylic acid can be converted to an ester using the conditions shown. Explain how a comparison of an IR spectrum of the reactant(s) and product can be used to determine whether the reaction was successful or not.

Under acidic conditions, alkene A can be isomerized to the more stable alkene B. How could IR spectroscopy be used to distinguish between A and B? [There are a few correct answers.]