A laboratory shelf holds eight amines: tert-butylamine, N-methylaniline, triethylamine…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A laboratory shelf holds eight amines: tert-butylamine, N-methylaniline, triethylamine, benzylamine, diisopropylamine, N,N-dimethylaniline, cyclohexylamine and ethylmethylamine. Sort them by the number of carbon groups on the nitrogen atom. Count how many are primary, how many are secondary and how many are tertiary. Then count how many are aromatic amines in the strict sense (nitrogen joined straight to a benzene ring). Finally, count the N-H bonds in all eight molecules together.
Need a reminder? The key ideaShow
The class of an amine is the number of carbon groups on the nitrogen atom: one, two or three. An aromatic amine has the nitrogen joined straight to a benzene ring. A saturated amine with carbon atoms is . Count isomers by choosing alkyl groups: there are 1, 1, 2, 4, 8 and 17 different alkyl groups with 1 to 6 carbon atoms.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. Write each amine as nitrogen with its groups, then count.
Step 1. Primary (one carbon group). tert-Butylamine, benzylamine and cyclohexylamine. That is 3. Each has two N-H bonds: .
Step 2. Secondary (two groups). N-methylaniline, diisopropylamine and ethylmethylamine. That is 3. Each has one N-H bond: .
Step 3. Tertiary (three groups). Triethylamine and N,N-dimethylaniline. That is 2, with no N-H bonds.
Step 4. Aromatic. N-methylaniline and N,N-dimethylaniline have the nitrogen on a benzene ring. That is 2.
Step 5. N-H bonds. .
Answer: 3 primary, 3 secondary, 2 tertiary, 2 aromatic, and 9 N-H bonds.
Check. , the number of amines on the shelf.
Watch out. tert-Butylamine looks like a "tertiary" amine, but its nitrogen holds only one carbon group.
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