Amines | Practice Problems, Examples & Solutions

Introduction

Chemistry : An Introduction to General, Organic, and Biological Chemistry

A student in your class asks you for advice on learning chemistry. Which of the following might you suggest?
a. forming a study group
b. skipping a lecture
c. visiting the professor during office hours
d. waiting until the night before an exam to study
e. being an active learner

Chemistry in Our Lives

Learning Chemistry: A Study Plan

01:37

Chemistry : An Introduction to General, Organic, and Biological Chemistry

Identify each activity, $\mathbf{a}-\mathbf{f},$ as an observation (O), a hypothesis (H) an experiment (E), or a conclusion (C). Lucia wants to develop a process for dyeing shirts so that the color will not fade when the shirt is washed. She proceeds with the following activities:
a. Lucia notices that the dye in a design fades when the shirt is washed.
b. Lucia decides that the dye needs something to help it combine with the fabric.
c. She places a spot of dye on each of four shirts and then places each one separately in water, salt water, vinegar, and baking soda and water.
d. After one hour, all the shirts are removed and washed with a detergent.
e. Lucia notices that the dye has faded on the shirts in water, salt water, and baking soda, while the dye did not fade on the shirt soaked in vinegar.
f. Lucia thinks that the vinegar binds with the dye so it does not fade when the shirt is washed.

Chemistry in Our Lives

Scientific Method: Thinking Like a Scientist

09:29

Chemistry : An Introduction to General, Organic, and Biological Chemistry

Read the labels on products used to wash your dishes. What are the names of some chemicals contained in those products?

Chemistry in Our Lives

Chemistry and Chemicals

Nomenclature of Amines

7 Practice Problems

01:51

Organic Chemistry

Draw structures corresponding to the following IUPAC names:
(a) Triisopropylamine
(b) Triallylamine
(c) $N$ -Methylaniline
(d) $N$ -Ethyl-N-methylcyclopentylamine
(e) N-Isopropylcyclohexylamine
(f) $N$ -Ethylpyrrole

Amines and Heterocycles

03:19

Chemistry and Chemical Reactivity

Draw structural formulas for all the primary amines with the formula $\mathrm{C}_{4} \mathrm{H}_{9} \mathrm{NH}_{2}$

Carbon: More Than Just Another Element

01:20

Organic Chemistry

One way of naming amines is to name in alphabetical order the alkyl groups attached to the nitrogen atom, using the prefixes $d i$ - and tri- if the groups are the same. An example is isopropylamine, whose formula is shown above. What are names for (a), (b), (c), and (d)? Build hand-held molecular models for the compounds in parts (a)-(d). a.(FIGURE CAN'T COPY)
b.(FIGURE CAN'T COPY)
c.(FIGURE CAN'T COPY)
d.(FIGURE CAN'T COPY)
Write bond-line formulas for (e) propylamine, (f) trimethylamine, and
(g) ethylisopropylmethylamine.

Families of Carbon Compounds

Structure of Amines

9 Practice Problems

03:54

Introduction to General, Organic and Biochemistry

(Chemical Connections $16 \mathrm{E}$ ) Classify each amino group in epinephrine and albuterol as primary, secondary, or tertiary. In addition, list the similarities and differences between the structural formulas of these two compounds.

Amines

04:47

Introduction to General, Organic and Biochemistry

Answer true or false.
(a) Aqueous solutions of amines are basic.
(b) Aromatic amines such as aniline in general are weaker bases than aliphatic amines such as cyclohexanamine.
(c) Aliphatic amines are stronger bases than inorganic bases such as $\mathrm{NaOH}$ and $\mathrm{KOH}$.
(d) Water-insoluble amines react with strong aqueous acids such as HCl to form watersoluble salts.
(e) If the pH of an aqueous solution of a $1^{\circ}$ aliphatic amine, $\mathrm{RNH}_{2}$, is adjusted to pH 2.0 by the addition of concentrated $\mathrm{HCl}$, the amine will be present in solution almost entirely as its conjugate acid, $\mathrm{RNH}_{3}^{+}$
(f) If the pH of an aqueous solution of a $1^{\circ}$ aliphatic amine, $\mathrm{RNH}_{2}$, is adjusted to pH 10.0 by the addition of $\mathrm{NaOH}$, the amine will be present in solution almost entirely as the free base, $\mathrm{RNH}_{2}$
(g) For a $1^{\circ}$ aliphatic amine, the concentrations of $\mathrm{RNH}_{3}^{+}$ and $\mathrm{RNH}_{2}$ will be equal when the pH of the solution is equal to the $\mathrm{p} K_{\mathrm{b}}$ of the amine.

Amines

06:00

Introduction to General, Organic and Biochemistry

There are eight primary amines with the molecular formula $\mathrm{C}_{3} \mathrm{H}_{13} \mathrm{N}$
(a) Name and draw a structural formula for each amine.
(b) Which of these amines are chiral?

Amines

Physical Properties of Amines

3 Practice Problems

01:12

Organic Chemistry

A tertiary amine reacts with hydrogen peroxide to form a tertiary amine oxide.
Tertiary amine oxides undergo a reaction similar to the Hofmann elimination reaction (Section 10.10 ), called a Cope elimination. In this reaction, a tertiary amine oxide, rather than a quaternary ammonium ion, undergoes elimination. A strong base is not needed for a Cope elimination because the amine oxide acts as its own base.
Does the Cope elimination have an alkene-like transition state or a carbanion-like transition state?

More About Amines • Reactions of Heterocyclic Compounds

01:28

Chemistry

Methylamine, $\mathrm{CH}_{3} \mathrm{NH}_{2},$ is responsible for the odor of rotting fish. Look at the following electrostatic potential map of methylamine, and explain
the observed polarity.

Liquids, Solids, and Phase Changes

02:05

Organic Chemistry

Arrange the compounds in order of increasing boiling point.

Amines

Physical Properties

Basicity of Amines

7 Practice Problems

03:54

Organic Chemistry

Which is the most basic nitrogen in each compound? Explain your choices.
(a)(FIGURE CANNOT COPY)
(b)(FIGURE CANNOT COPY)
(c)(FIGURE CANNOT COPY)

Amines

03:36

Organic Chemistry

While amides are much less basic than amines, they are much stronger acids. Amides have $\mathrm{p} K_{\mathrm{a}}$ values in the range $14-16$ whereas for amines, $\mathrm{p} K_{\mathrm{a}}=33-35$
FIGURES CANT COPY

Carboxylic Acids and Their Derivatives

02:04

Chemistry: An Atoms-Focused Approach

The $p K_{b}$ values in Appendix 5 tell us that methylamine is a stronger base than ammonia and that dimethylamine is even stronger. Use the differences in their molecular structures to explain this trend in the strengths of these three bases.

Organic Chemistry: Fuels, Pharmaceuticals, and Modern Materials

Factors that Affect Amine Basicity

4 Practice Problems

04:57

Organic Chemistry

Varenicline (trade name Chantix) is a drug used to help smokers quit their habit. (a) Which N atom in varenicline is most basic? Explain your choice. (b) What product is formed when varenicline is treated with HCI?

Amines

01:46

Organic Chemistry

Which compound is the stronger base?

Amines

03:46

Organic Chemistry

Which compound in each pair is more basic: (a) (CH$_3$)$_2$NH and NH$_3$; (b) CH$_3$CH$_2$NH$_2$ and CICH$_2$CH$_2$NH$_2$ ?

Amines

Relative Basicity of Amines and Other Compounds

Salts of Amines

4 Practice Problems

01:06

Organic Chemistry

If a quaternary ammonium ion can undergo an elimination reaction with a strong base, why can't a protonated tertiary amine undergo the same reaction?

Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds

02:33

Organic Chemistry

LSD (a hallucinogen) and codeine (a narcotic) are structurally more complex derivatives of
2-phenylethylamine. Identify the atoms of 2-phenylethylamine in each of the following compounds.

Amines

Interesting and Useful Amines

Spectroscopy of Amines

4 Practice Problems

02:34

Introduction to General, Organic and Biochemistry

How many hydrogen atoms does pyrrolidine have? How many does purine have? Write the molecular formula of each amine.

Amines

02:16

Organic Chemistry

Evidence for restricted rotation around amide CO-N bonds comes from NMR studies. At room temperature, the $^{1} \mathrm{H}$ NMR spectrum of $N, N$ -dimethylformamide shows three peaks: 2.9 \& (singlet, 3 H), 3.0 \& (singlet, 3 H),
$8.0 \delta(\text { singlet, } 1 \mathrm{H}) .$ As the temperature is raised, however, the two singlets at
2.98 and 3.08 slowly merge. At $180^{\circ} \mathrm{C},$ the $^{1} \mathrm{H}$ NMR spectrum shows only two peaks: $2.95 . \delta$ (singlet, $6 \mathrm{H}$ ) and 8.08 (singlet, 1 H). Explain this temperature-dependent behavior.
CAN'T COPY THE FIGURE

Biomolecules: Amino Acids, Peptides, and Proteins

10:16

Organic Chemistry

When acetone is treated with anhydrous ammonia in the presence of anhydrous calcium chloride (a common drying agent), crystalline product $\mathbf{C}$ is obtained on concentration of the organic liquid phase of the reaction mixture. These are spectral data for product C:
$\mathrm{MS}(m / z): 155\left(\mathrm{M}^{+}\right), 140$
IR $\left(\mathrm{cm}^{-1}\right): 3350$ (sharp), $2850-2960,1705$
$^{1} \mathrm{H} \mathrm{NMR}(\delta): 2.3(\mathrm{s}, 4 \mathrm{H}), 1.7\left(1 \mathrm{H} ; \text { disappears in } \mathrm{D}_{2} \mathrm{O}\right),$ and $1.2(\mathrm{s}, 12 \mathrm{H})$
(a) What is the structure of $\mathbf{C ?}$
(b) Propose a mechanism for the formation of $\mathbf{C}$.

Amines

Reactions of Amines with Ketones and Aldehydes (Review)

3 Practice Problems

01:33

Organic Chemistry

What two enamines are formed when 2-methylcyclohexanone is treated with (CH$_3$)$_2$NH?

Aldehydes and Ketones-Nucleophilic Addition

Addition of 2 Degree Amines

03:26

Organic Chemistry

What 1$^\circ$ amine and carbonyl compound are needed to prepare each imine?

Aldehydes and Ketones-Nucleophilic Addition

Addition of 1 Degree Amines

04:00

Organic Chemistry

(a) What two components are needed to prepare para red by azo coupling? (b) What two components are needed to prepare alizarine yellow R?

Amines

Application: Synthetic Dyes

Aromatic Substitution of Arylamines and Pyridine

1 Practice Problems

03:57

Organic Chemistry

Draw the product formed in each reaction.

Amines

Substitution Reactions of Aryl Diazonium Salts

Alkylation of Amines by Alkyl Halides

0 Practice Problems

Acylation of Amines by Acid Chlorides Primary and secondary amines react with acid halides to form amides. T

2 Practice Problems

01:31

Organic Chemistry

Will an amide be the final product obtained from the reaction of an acyl chloride with pyridine in an aqueous solution? Explain your answer.
The positively charged nitrogen in the initially formed carbonyl compound causes pyridine to be an excellent leaving group. Therefore, the compound hydrolyzes rapidly. As a result, the final product of the reaction is a carboxylic acid. (If the final pH of the solution is greater than the $\mathrm{p} K_{\mathrm{a}}$ of the carboxylic acid and the $\mathrm{p} K_{\mathrm{a}}$ of pyridine, both will be predominantly in their basic form.)

More About Amines • Reactions of Heterocyclic Compounds

05:45

Organic Chemistry

What amide(s) can be used to prepare each amine by reduction?

Amines

Formation of Sulfonamides

0 Practice Problems

Amines as Leaving Groups: The Hofmann Elimination

3 Practice Problems

02:19

Organic Chemistry

What products would you expect from Hofmann elimination of the following amines? If more than one product is formed, indicate which is major.
(FIGURE CANNOT COPY)

Amines and Heterocycles

08:19

Organic Chemistry

Draw the product formed by treating each compound with excess CH$_3$I, followed by Ag$_2$O, and then heat.

Amines

Hofmann Elimination

Oxidation of Amines; The Cope Elimination

1 Practice Problems

05:27

Organic Chemistry

Does the Cope elimination have an alkene-like transition state or a carbanion-like transition state?

More About Amines • Heterocyclic Compounds

Reactions of Amines with Nitrous Acid

2 Practice Problems

02:54

Organic Chemistry

Draw the product formed when each compound is treated with NaNO$_2$ and HCI.

Amines

Reaction of Amines with Nitrous Acid

Reactions of Arenediazonium Salts

1 Practice Problems

05:12

Organic Chemistry

Draw the product formed when C$_6$H$_5$N$_2$$^+$Cl$^-$ reacts with each compound.

Amines

Coupling Reactions of Aryl Diazonium Salts

Synthesis of Amines by Reductive Amination

6 Practice Problems

01:40

Biochemistry

RECALL Draw the mechanism of transamination with pyridoxal phosphate.

The Metabolism of Nitrogen

02:10

Organic Chemistry

Show how you could prepare the following amino acids using a reductive amination:
(a) Methionine
(b) Isoleucine

Biomolecules: Amino Acids, Peptides, and Proteins

13:26

Organic Chemistry

Azo compounds can be reduced to amines by a variety of reagents including stannous
$$\mathrm{Ar}-\mathrm{N}=\mathrm{N}-\mathrm{Ar}^{\prime} \quad \stackrel{\mathrm{SnCl}_{2}}{\longrightarrow} \mathrm{ArNH}_{2}+\mathrm{Ar}^{\prime} \mathrm{NH}_{2}$$
This reduction can be useful in synthesis as the following example shows:
$$
\mathbf{B}\left(\mathrm{C}_{16} \mathrm{H}_{18} \mathrm{N}_{2} \mathrm{O}_{2}\right) \stackrel{\mathrm{sn} \mathrm{Cl}_{2}}{\longrightarrow}
$$
two molar equivalents of $\mathbf{C}\left(\mathrm{C}_{8} \mathrm{H}_{11} \mathrm{NO}\right) \stackrel{\text { acetic anhydride }}{\longrightarrow}$ phenacetin $\left(\mathrm{C}_{10} \mathrm{H}_{13} \mathrm{NO}_{2}\right)$
Give a structure for phenacetin and for the intermediates $\mathbf{A}, \mathbf{B},$ and $\mathbf{C} .$ (Phenacetin, formerly used as an analgesic, is also
the subject of Problem $17.45 .)$

Amines

Synthesis of Amines by Acylation–Reduction

0 Practice Problems

Syntheses Limited to Primary Amines

3 Practice Problems

02:25

Organic Chemistry

Primary amines can also be prepared by the reaction of an alkyl halide with azide ion, followed by catalytic hydrogenation. What advantage do this method and the Gabriel synthesis have over the synthesis of a primary amine using an alkyl halide and ammonia?

Reactions of Carboxylic Acids and Carboxylic Derivatives

08:44

Organic Chemistry

Primary amines react with esters to yield amides: $\mathrm{RCO}_{2} \mathrm{R}^{\prime}+\mathrm{R}^{\prime \prime} \mathrm{NH}_{2} \rightarrow$ RCONHR" + R'OH. Propose a mechanism for the following reaction of an $\alpha, \beta$ -unsaturated ester. (EQUATION CAN'T COPY)

Aldehydes and Ketones: Nucleophilic Addition Reactions

01:46

Organic Chemistry

Write a mechanism that explains how the reaction of 1 mol of bromocthane with 1 mol of ammonia can lead to a mixture ethylamine, diethylamine, triethylamine, and tetracthylammonium bromide rather than pure ethylamine.

Amines

Substitution reactions with amines

0 Practice Problems

Reductive amination

2 Practice Problems

00:55

Chemistry : An Introduction to General, Organic, and Biological Chemistry

Describe the reactions of transamination, oxidative deamination, and the entry of amino acid carbons into the citric acid cycle.
Draw the condensed structural formula for the $\alpha$ -keto acid produced from each of the following in transamination:
$\mathrm{NH}_{3}$
$\mathrm{I}$
$\mathrm{a} . \mathrm{H}-\mathrm{CH}-\mathrm{COO}^{-}$ Glycine
$$_{1}^{+} \mathrm{N}_{3}$$
b. $\mathrm{CH}_{3}-\mathrm{CH}-\mathrm{COO}^{-}$ Alanine

Metabolic Pathways and Energy Production

Degradation of Amino Acids

Acylation of amines

0 Practice Problems