tiểu-luận-hóa-học-hữu-cơ-Nguyễn-Thị-Dịu-27-02-2021

HUE UNIVERSITY
HUE UNIVERSITY OF EDUCATION
FACULTY OF CHEMISTRY
-------?&@-------

NGUYỄN THỊ DỊU

AMINES AND DIAZONIUM SALTS
ESSAY OF ORGANIC CHEMISTRY

Lecturer:

TRẦN ĐÔNG TIẾN

Class:

Chemistry 3E

Student Code:

18S2011007

Course:

2018 - 2022
Hue, 01/2021


ACKNOWLEDGEMENT
I would like to thank Mr. Tran Dong Tien for imparting valuable knowledge and
experiences to me, helping and creating all favorable conditions so that I can complete

this thematic exercise perfectly.
I would also like to thank my friends who supported me in the writing process
of the essay by giving me some useful advices and encouraging me when I am busy
and tired.
Hue, January 2021

Nguyen Thi Diu


TABLE OF CONTENTS
Page
INTRODUCTION........................................................................................................2
1. Reasons of the topic..................................................................................................2
2. Purposes of the topic.................................................................................................2
3. Research methods......................................................................................................2
MAIN CONTENTS OF THE TOPIC.........................................................................3
Chapter 1: Summary .....................................................................................................3
1.1. Amines...................................................................................................................3
1.1.1. Introduction........................................................................................................3
1.1.2. Synthesis of amines............................................................................................5
1.1.3. Reactions of amines...........................................................................................7
1.2. Diazonium salts......................................................................................................9
1.2.1. Introduction........................................................................................................9
1.2.2. Preparation.........................................................................................................9
1.2.3. Reaction of diazonium salts..............................................................................10
Chapter 2: Problems and solutions...............................................................................12
CONCLUSIONS........................................................................................................25
REFERENCES...........................................................................................................25

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INTRODUCTION
1. Reasons of the topic
Organic chemistry is a science that studies the structure, composition,
properties, reaction mechanism, synthesis methods and application of organic
compounds and organic materials... as well as many different compounds.
These days, the relevant questions and exercise system of organic chemistry are
greatly various. The amine is an indispensable part of the curriculum. Therefore, I
choose the topic "AMINES AND DIAZONIUM SALTS" to study sharply about
amine.
2. Purposes of the topic
- Systematizing knowledge about amines;
- Systematizing and solving questions and exercises of chapter amines in the
section of organic chemistry 2.
3. Research methods
- Synthesizing presentations from references related to amines;
- Collecting, classifying and compiling chemical exercises about amines.

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MAIN CONTENTS
CHAPTER 1: SUMMARY
1.1. Amines
1.1.1. Introduction:
Amines are basic nitrogen-containing compounds that are derivatives of
ammonia (NH3), in which one or more alkyl, cycloalkyl, or aryl groups replace
hydrogen and bond to the nitrogen atom.
+ Classification of amines:

- Amine: organic molecule in which a nitrogen atom is bonded to one or more
alkyl group
- Amine: An organic base formed by replacing one or more of the hydrogen
atoms of ammonia by organic groups.
- Any of a class of compounds derived from ammonia by replacement of one or
more hydrogen atoms with organic groups.
Amines are classified based on:
- Number of nitrogen atom;
- Constitutional characteristic of hydrocarbon groups bonded to the nitrogen
atom:
+ Aliphatic amine (alkylamine)
+ Aromatic amine (arylamine)

+ Amines of primary, secondary and tertiary:
Unlike alcohols and alkyl halides, which are classified as primary,
secondary, or tertiary according to the degree of substitution at the carbon that
bears the functional group, amines are classified according to their degree of
substitution at nitrogen.
- Primary (1°) amine: one alkyl or aryl group attached to the nitrogen atom.

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- Secondary (2°) amine: two alkyl or aryl groups attached to the nitrogen atom.
- Tertiary (3°) amine: three alkyl or aryl groups attached to the nitrogen atom.
- Quaternary (4o) amine: an ion in which nitrogen is bonded to four alkyl or aryl
groups and bears a positive charge.

+ Nomenclature of amines
The naming of amine depends on the classification of amine. They are named

using either systematic (IUPAC System) or common names.

Secondary and tertiary amines having identical alkyl groups are named by using the
prefix di- or tri- with the name of the primary amine.

Amines are named in two main ways in the IUPAC system, either as
alkylamines or as alkanamines. When primary amines are named as alkylamines, the
ending -amine is added to the name of the alkyl group that bears the nitrogen. When
named as alkanamines, the alkyl group is named as an alkane and the -e ending
replaced by -amine.
Example
Primary
amine

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1.1.2. Synthesis of amines
+ Nucleophilic Substitution Routes to Amines:
Direct Nucleophilic Substitution by SN2 reaction of an alkyl halide with NH 3 or an
amine (alkylation of NH3 or an amine: Hofmann, 1850 or by amination of alkyl
halides)

SN2 mechanism: the unhindered alkyl halide = CH3X or RCH2X.
A very large excess of NH3 ⇒ a mixture of 1°, 2° and 3° amines;
A very large excess of alkyl halide ⇒ a mixture of 3° amine and quaternary
ammonium salt.

* The Gabriel Synthesis of 1° Amines (Gabriel, 1887) = Traditional Gabriel
synthesis: The Gabriel synthesis converts an alkyl halide into a 1° amine by a twostep process: nucleophilic substitution followed by hydrolysis.

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Disadvantages of Gabriel synthesis:
- This method generally fails with secondary alkyl halides.
- The first technique often produces low yields or side products.
- Separation of phthalhydrazide can be challenging. For these reasons, other methods
for liberating the amine from the phthalimide have been developed. Even with the use
of the hydrazinolysis method, the Gabriel method suffers from relatively harsh
conditions.
+ Reduction of Other Functional Groups That Contain Nitrogen
- From nitro compounds, oximes:

The most frequently used methods employ catalytic hydrogenation, or treatment of the
nitro compound with acid and iron. Zinc, tin, or a metal salt such as SnCl 2 can also be
used:

- From nitriles:

- From amides:

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- From alkyl azides:

+ Reductive Amination of Aldehydes and Ketones (or reductive alkylation of the
amine)
Aldehydes and ketones can be converted to amines through catalytic or

chemical reduction in the presence of ammonia or an amine. Primary, secondary, and
tertiary amines can be prepared this way:

+ Degradation reactions: Preparation of Primary Amines through the Hofmann
and Curtius Rearrangements
Hofmann Rearrangement Amides with no substituent on the nitrogen react with
solutions of bromine or chlorine in sodium hydroxide to yield amines through a
reaction known as the Hofmann rearrangement or Hofmann degradation:

1.1.3. Reactions of amines

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+ Basicity of Amines
Both amine and ammonia produce basic aqueous solutions. Amine and
ammonia are relatively weak bases due to the acceptor of protons. Most are stronger
bases than water but are far weaker bases than hydroxide ions, alkoxide ions, and
alkanide anions.

A convenient way to compare the base strengths of amines is to compare the pKa
values of their conjugate acids, the corresponding alkylaminium ions. When
considering the basicity of amines, bear in mind that:
The more basic than amine, the weaker its conjugate acid; The more basic than
amine, the larger the pKa of its conjugate acid.
+ Amines react as bases with a variety of organic and inorganic acids

The equilibrium for an amine that is relatively more basic will lie more toward
the left in the above chemical equation than for an amine that is less basic.
The aminium ion of a more basic amine will have a larger pKa than the

aminium ion of a less basic amine. When we compare aminium ion acidities in terms
of this equilibrium, we see that most primary alkylaminium ions (RNH 3+) are less
acidic than ammonium ions (NH 4+). In other words, primary alkylamines (RNH 2) are
more basic than ammonia (NH3):

+ Replacement of hydrogen atom bonded to nitrogen
- Alkylation of amines (or NH3): Hofmann's exhaustive alkylation:

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Acylation of amines:

- Reaction with aldehydes and ketones: Reductive amination of aldehydes and ketones

1.2. Diazonium salts
1.2.1. Introduction
Diazonium compounds or diazonium salts are a group of organic compounds
sharing a common functional group R−N2+X−
where R can be any organic group, such as an alkyl or an aryl, and X is an
inorganic or organic anion, such as a halogen.
1.2.2. Preparation
+ Preparation of diazonium salt’s and diazonium cation structure
Reactions of Primary Aliphatic Amines with Nitrous Acid:

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+ Acid-base equilibrium of diazonium salts

1.2.3. Reaction of diazonium salts
+ Chemical properties/Reaction of diazonium salts
- Reaction involving replacement of diazonium group:

- Reactions involving retention of diazonium group: Azo coupling reaction:

Specific examples:

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CHAPTER 2: PROBLEMS AND SOLUTIONS
Problem 1 (Probem 25.1, page 950, [1]) Classify each amine in the following
compounds as 1°, 2°, 3°.

Solution: Amines are classified as 1o , 2o , or 3o by the number of alkyl groups bonded
to the nitrogen atom.

Problem 2 (Problem 25.2, page 950, [1]) Draw the structure of a compound of
molecular formula C4H11NO that fi ts each description:
(a) a compound that contains a 1° amine and a 3° alcohol;
(b) a compound that contains a 3° amine and a 1° alcohol.

Problem 3 ( Problem 25.5, page 953, [1]) Name each amine.

Solution:
a. Butan-2-amine

b. Dibutylamine

c. N,N-dimethylcyclohexanamine

d. 2-methylnonan-5-amine

e. N-ethylhexan-3-amine

f. 2-methyl-N-propylcyclopentan-1-amine

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Problem 4 (Problem 25.6, page 954, [1]) Draw a structure corresponding to each
name.
a. 2,4-dimethyl-3-hexanamine

b. N-methylpentylamine

c. N-isopropyl-p-nitroaniline

d. N-methylpiperidine

e. N,N-dimethylethylamine

f. 2-aminocyclohexanone

g. N-methylaniline

h. N-ethylaniline

Solutions:

Problem 5 (Problem 25.7, page 954, [1]) Arrange each group of compounds in order of
increasing boiling point.

Solutions:
Primary (1°) and 2° amines have higher bp’s than similar compounds (like
ethers) incapable of hydrogen bonding, but lower bp’s than alcohols that have stronger
intermolecular hydrogen bonds. Tertiary amines (3°) have lower boiling points than 1 o
and 2o amines of comparable molecular weight because they have no N–H bonds.

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Problem 6 (Probem 25.41, page 994, [1]) Give a systematic or common name for each
compound

Solution:

Problem 7 (Problem 25.42, page 994, [1]) Draw the structure that corresponds to each
name.
a. cyclobutylamine

f. N-methylcyclopentylamine

b. N-isobutylcyclopentylamine

g. cis-2-aminocyclohexanol

c. tri-tert-butylamine

h. 3-methyl-2-hexanamine

d. N,N-diisopropylaniline

i. 2-sec-butylpiperidine

e. N-methylpyrrole

j. (2S)-2-heptanamine

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Solution:

Problem8 (Problem 25.44, page 994, [1]) How many stereogenic centers are present in
each compound? Draw all possible stereoisomers.

Solution:

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Problem 9 (Problem 25.11, page 961, [1]) Draw the product of each reaction.

Solutions:
SN2 reaction of an alkyl halide with NH3 or an amine forms an amine or an ammonium

salt.

Problem 10 (Problem 25.45, page 954, [1]) Which compound in each pair is the
stronger base?

Solution:

Problem 11 (Problem 25.58, page 996, [1]) How would you prepare benzylamine
(C6H5CH2NH2) from each compound? In some cases, more than one step is required.
a. C6H5Cl

e. C6H5CH3

b. C6H5CN

f. C6H5COOH

c. C6H5CONH2

g. C6H5NH2

d. C6H5CHO

h. benzene

Solution:

18

Problem 12 (Problem 25.60, page 996, [1]) What products are formed when Nethylaniline (C6H5NHCH2CH3) is treated with each reagent?
a. HCl
b. CH3COOH

f. CH3I (excess), followed by Ag2O and ∆
g. CH3CH2COCl

c. (CH3)2C =O

h. The product in (g), then HNO3, H2SO4

d. CH2O, NaBH3CN

i. The product in (g), then [1] LiAlH4; [2] H2O

e. CH3I (excess)

j. The product in (h), then H2, Pd-C

Solution:

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Problem 13 (Problem 25.61, page 996, [1]) Draw the products formed when pmethylaniline (p-CH3C6H4NH2) is treated with each reagent.
a. HCl

f. CH3COCl, AlCl3

b. CH3COCl

g. CH3COOH

c. (CH3CO)2O

h. NaNO2, HCl

d. CH3I

i. Step (b), then CH3COCl.AlCl3

e. (CH3)2C=O

j. CH3CHO, NaBH3CN

Solution:

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Problem

14

(Problem

25.62,

page

998,

[1])

How

would

you

convert

CH3CH2CH2CH2NH2 into each compound?
a. CH3CH2CH2CH2NHCOC6H5

b. CH3CH2CH2CH2N=C(CH2CH3)2

c. CH3CH2CH=CH2

d. CH3CH2CH2CH2NHCH2C6H5

e. CH3CH2CH2CH2NHCH2CH3

f. [CH3CH2CH2CH2N(CH3)3]+ I–

Solution:

Problem 15 (Problem 25.72, page 998, [1]) Draw a stepwise mechanism for the
following reaction.

Solution:

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Problem 16 (Problem 25.77, page 998, [1]) Devise a synthesis of each compound from
benzene. You may use any other organic or inorganic reagents.

Solution:

22


Problem 17 (Problem 25.80, page 998, [1]) Safrole, which is isolated from sassafras,
can

be

converted

to

the

illegal

stimulant

MDMA

(3,4methylenedioxymethamphetamineMDMA, “Ecstasy”) by a variety of methods.
(a) Devise a synthesis that begins with safrole and uses a nucleophilic substitution
reaction to introduce the amine.
(b) Devise a synthesis that begins with safrole and uses reductive amination to
introduce the amine.

Solution:

23


Problem 18 (Problem 25.89, page 1001, [1]) Draw the product Y of the following
reaction sequence. Y was an intermediate in the remarkable synthesis of
cyclooctatetraene by Wilstatter in 1911.

Solution:

Problem 19: Write the chemical equation according to the following conversion
diagram:

Solution:

24


Problem 20 Give the structures of A,B and C in the following reaction:

Solution:

Problem 21 Compound A (C5H11O2N) is a photoactive liquid. Reducing A by H2 with

Ni catalyst will be photoactive B (C5H13N). Let B react with HNO2 acid to obitan a
mixture of photosensitive alcohol C and tert-amylic alcohol (2-methyl-2-butanol).
Determine the structural formula of A. Using the structural formula, write down the
equations for the formation of B, C and tert-amylic alcohol from A.
Solution:

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