1. Sample Problem 18.1 IUPAC Names for Amines
Give the IUPAC name for the following amine:
Solution
Step 1 Name the longest carbon chain bonded to the N atom by replacing the e of its alkane name with amine. The longest carbon chain bonded to the N atom has four carbon atoms, which is named by replacing the e in the alkane name with amine to give butanamine.
Step 2 Number the carbon chain to show the position of the amine group and other substituents. The N atom in the amine group is attached to carbon 1 of butanamine.

2. Sample Problem 18.1 IUPAC Names for Amines
Continued
Step 3 Any alkyl group attached to the nitrogen atom is indicated by the prefix N- and the alkyl name, which is placed in front of the amine name. Alkyl groups attached to the N atom are listed alphabetically.
Study Check 18.1
Draw the condensed structural formula for N-ethyl-1-propanamine.
Answer

3. Sample Problem 18.2 Common Names of Amines
Give a common name for each of the following amines:
Solution
a. This amine has one ethyl group attached to the nitrogen atom; its name is ethylamine.
b. The common name for an amine with three methyl groups attached to the nitrogen atom is trimethylamine.
Study Check 18.2
Draw the condensed structural formula for butyldimethylamine.
Answer

4. Sample Problem 18.3 UPAC Names for Compounds with Two Functional Groups
Give the IUPAC name for the following compound, which is used in the production of methadone:
Solution
Step 1 Identify the functional group with the highest priority and use the longest carbon chain to give the compound name. Because the hydroxyl group has a higher priority than the amine group, the compound is named as an alcohol.
Step 2 Number the carbon chain, and give the position and name of the main group and the substituent group on the carbon chain.

5. Sample Problem 18.3 UPAC Names for Compounds with Two Functional Groups
Continued
Study Check 18.3
Draw the condensed structural formula for 3-aminopentanal.
Answer

6. Sample Problem 18.4 Classifying Amines
Classify each of the following amines as primary (1°), secondary (2°), or tertiary (3°):
Solution
a. This is a primary (1°) amine because there is one alkyl group (cyclohexyl) attached to the nitrogen atom.
b. This is a tertiary (3°) amine. There are three alkyl groups (two methyls and one ethyl) attached to the nitrogen atom.
c. This is a secondary (2°) amine with two carbon groups, methyl and phenyl, bonded to the nitrogen atom.
d. The nitrogen atom in this line-angle structural formula is bonded to two alkyl groups, which makes it a secondary (2°) amine.

7. Sample Problem 18.4 Classifying Amines
Continued
Study Check 18.4
Classify the following amine as primary (1°), secondary (2°), or tertiary (3°):
Answer
tertiary (3°)

8. Sample Problem 18.5 Boiling Points and Solubility of Amines
The compounds trimethylamine and ethylmethylamine have the same molar mass. Why is the boiling point of trimethylamine (3 °C) lower than that of ethylmethylamine (37 °C)?
Solution
With polar N—H bonds, ethylmethylamine molecules form hydrogen bonds with each other. Thus, a higher temperature is required to break the hydrogen bonds and form a gas. However, trimethylamine, which is a tertiary amine, does not have N—H bonds and cannot hydrogen bond with other trimethylamine molecules. It does not need as high a temperature to form a gas.
Study Check 18.5
Answer
Hydrogen bonding makes amines with six or fewer carbon atoms soluble in water. When there are seven or more carbon atoms in the alkyl portions of an amine, the longer nonpolar hydrocarbon chains diminish the solubility effect of the polar amine group.

9. Sample Problem 18.6 Reactions of Amines
Write a balanced chemical equation that shows ethylamine:
a. acting as a weak base in water
b. neutralized by HCl
Solution
a. CH3—CH2—NH2 + H2O CH3—CH2—NH3 + OH−
b. CH3—CH2—NH2 + HCl CH3—CH2—NH3 Cl−
Study Check 18.6
Draw the condensed structural formula for the ammonium salt formed by the reaction of trimethylamine and HCl.
Answer + +

10. Sample Problem 18.7 Heterocyclic Amines
Identify the heterocyclic amines that are part of the structure of nicotine.
Solution
Nicotine contains two heterocyclic rings. The 6-atom ring with one N atom and three double bonds is pyridine, and the 5-atom ring with one N atom and no double bonds is pyrrolidine. The N atom in the pyrrolidine ring is bonded to a methyl group (—CH3).

11. Sample Problem 18.7 Heterocyclic Amines
Continued
Study Check 18.7
Sedamine is used as a sleep aid. Identify the heterocyclic amine that is part of the structure of sedamine.
Answer
piperidine

12. Sample Problem 18.8 Solution Study Check 18.8 Answer
Place the following in order of occurrence for nerve impulses:
a. Neurotransmitters diffuse across synapse to receptors on dendrites.
b. Neurotransmitters move away from receptors.
c. An electrical signal reaches the axon terminal of a nerve cell.
d. Reuptake moves neurotransmitters into the vesicles for storage.
e. Vesicles release neurotransmitters into the synapse of nearby nerve cells.
f. Neurotransmitters stimulate receptors to send new nerve impulse.
Solution
c, e, a, f, b, d
Study Check 18.8
How does an excitatory neurotransmitter send a nerve impulse at the receptor?
Answer
When the neurotransmitter attaches to the receptor, ion channels open and positive ions flow to nearby nerve cells creating new electrical impulses.

13. Sample Problem 18.9 Amidation
Draw the condensed structural formula for the amide product in each of the following reactions:
Solution
The condensed structural formula for the amide product can be drawn by attaching the carbonyl group from the acid to the nitrogen atom of the amine. The —OH group is removed from the acid and —H from the amine to form water.

14. Sample Problem 18.9 Amidation
Continued
Study Check 18.9
Draw the condensed structural formulas for the carboxylic acid and amine needed to prepare the following amide. (Hint: Separate the N and C O of the amide group, and add —H and —OH to give the original amine and carboxylic acid.)
Answer

15. Sample Problem 18.10 Naming Amides
Give the IUPAC name for the following amide:
Solution
Step 1 Replace oic acid (IUPAC) or ic acid (common) in the carboxyl name with amide.
Step 2 Name each substituent on the N atom using the prefix N- and the alkyl name.

16. Sample Problem 18.10 Naming Amides
Continued
Study Check 18.10
Draw the condensed structural formula for N,N-dimethylbenzamide.
Answer

17. Sample Problem 18.11 Hydrolysis of Amides
Draw the condensed structural formulas and give the IUPAC names for the products of the hydrolysis of N-methylpentanamide with NaOH.
Solution
In hydrolysis, the amide bond is broken between the carboxyl carbon atom and the nitrogen atom. When NaOH is used, the products are the carboxylate salt and an amine.

18. Sample Problem 18.11 Hydrolysis of Amides
Continued
Study Check 18.11
Draw the condensed structural formulas for the products obtained from the hydrolysis of N-methylbutyramide with HBr.
Answer