Problem Set 10 – Reactions of amines

1. Putrescine and cadaverine are found in rotting flesh. Putrescine (C₄H₁₂N₂) may be synthesized by treating 1,2-dibromoethane with KCN followed by hydrogenation. Treatment of 1,5-dibromopentane with ammonia gives cadavrine (C₅H₁₄N₂).

a. What is the structure of putrescine?

b. What is the structure of cadavrine?

2. Choline, C₅H₁₅O₂N, is a constituent of phospholipids. It dissolves in water to give a basic solution. It can be prepared by reaction of ethylene oxide with trimethylamine in the presence of water. Acetylcholine, C₇H₁₇O₃N, is its acetyl derivative.

a. What is the structure of choline?

b. What is the structure of acetylcholine?

3. Write equations for each step in the following syntheses:

a. toluene ® p-fluorotoluene

b. toluene ® m-fluorotoluene

4. Coniine, C₈H₁₇N, is the toxic ingredient of poison hemlock, drunk by Socrates. When subject to exhaustive methylation and Hofmann elimination, coniine gives 5-(N,N-dimethylamino)-1-octene. If coniine is a secondary amine, what is its structure?

5. Atropine, C₁₇H₂₃NO₃, is a poisonous alkaloid isolated from Atropa belladonna, deadly nightshade. Base hydrolysis gives tropic acid, C₆H₅CH(CH₂OH)CO₂H, and tropine, C₈H₁₅NO. Tropine, an optically inactive alcohol reacts with H₂SO₄ to give tropidene:

What is the structure of atropine?

6. When pethidine, the active ingredient in the analgesic Dolantine, undergoes two exhaustive methylations, each followed by a Hofmann elimination, then an ozonolysis, the following results are obtained:

Propose a structure for pethidine.