Chemistry 332 - Winter 1997

Homework - Chapter 9 - Answer Key

McMurry, pp 281 - 284:
Problems 9.20, 22-24, 26-32, 34-40, 44, 47


1. Write complete names for each of the following:

a)

(R)-5-ethyl-8-hydroxyoctanal

b)

4,4-dimethyl-2,5-cyclohexadienone

2. Write a complete mechanism for the acid-catalyzed formation of the cyclic acetal between acetone and cis-1,2-cyclopentanediol.
Explain why an acetal is not formed with the trans isomer.

It is sterically difficult for the trans-1,2-diol to get both OH groups to connect to the same carbon of acetone.

3. Develop a synthetic sequence for 3-ethyl-3-hexanol that uses as organic starting materials only alcohols having four carbons or fewer.

4. Explain how acetone in the presence of radioactively-labelled water (H₂O¹⁸) slowly becomes radioactive itself.

The hydration reaction (addition of water as a nucleophile) does occur, although the equilibrium constant strongly favors acetone rather than 2,2-propanediol. Reversal of the reaction could eliminate either normal water or radioactive water.

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