1. General

Review the following topics: recrystallization theory, vacuum filtration, ¹³C-NMR and DEPT spectroscopy

2. Experiment

Safety note: Isopentyl nitrite is a powerful heart stimulant. Avoid breathing in the vapors.

In is important that both solids are dissolved in 1,2-dimethoxyethane first, before adding the isopentyl nitrite.

The color change from purple to orange yellow is gradually. If the solution remains purple, add 1-2 drops of pure isopentyl nitrite first and reflux for five more minutes. If this does not cause the color to change, add ~10 mg of the acid dissolved in 1 mL of 1,2-dimethoxyethane.

The final product tends to dissolve and precipitate very slowly during the recrystallization process. Be patient when you add additional solvent to dissolve it. It might be a good idea to place a watch glass with ice on top of the Erlenmeyer flask. Why?

When you obtain the IR spectrum of the compound, make sure that you do not use too much of the sample to prepare the KBr pellet. You will only need ~1% of your sample in the KBr pellet.

For the UV-Vis spectrum, you will need to use a quartz cuvette (~$150) to perform the measurement. Why?

3. Things to think about

a. How would the ¹³C-NMR spectrum of tetraphenylnaphthalene (TPN) change if you lower the temperature of the solution.

b. Why is tetraphenylcyclopentadienone dark purple in color and while tetraphenylnaphthalene is white?

c. How do you explain the double melting point of TPN?

d. How do you calculate the e-value for a given wavelength?