Amines
1435-1436
2014-2015
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Amines
Learning Objectives
Chapter ten discusses the following topics and by the end of this chapter the
students will:
 Know the structure and classification of amines
 Know the naming rules for amines & precedence order of functional groups in
compounds have more than one functional group.
 Know the physical properties of amines
 Know the effect of lone pair of electrons of N atom on basic properties of amines
Know the different methods used in synthesis of amines
 Know the reactions of amines; in addition to behaving as bases amines can be
nucleophiles.
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Amines
Structure & Classification
Amines are derivatives of ammonia that have one or more of the
hydrogen replaced with alkyl and/ or aryl group.
Amines: are a class of organic compounds that contain the N group
Amines are formed in many biological systems. So it used as drugs and
medicines.
Classification Of Amines
H
R
N:
H
primary (1o) amines
R
H
R
N:
R
secondary (2o) amines
R
N:
R
tertiary (3o) amines
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Amines
Common Nomenclature Of Amines
 The common names of amines are derived by listing the name (s) of the group
(s) surrounding the nitrogen (in alphabetical order) and adding the suffix
amine.(N.B. if two vowels come together ; the first must be omitted e.g.
ethanamine.
 Symmetrical 3° &2° amines (i.e. the substituents surrounding the N atom are
identical) are named by adding the multiplication prefix (di or tri) to the name of
H
the alkyl group.
N
CH3
H3C N CH3
H3C NH2
Methylamine
Benzyl methyl amine
Trimethyl amine
 Structures with higher priority groups, the NH2 group is called amino
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Amines
IUPAC Names Of Primary Amines
 If the compound does not contain a functional group except amino group,
then the compound is named by finding the longest alkane chain containing the
amino group and replacing the e in the IUPAC name by the suffix amine
 However if the compound contain other functional groups then the
order of precedence determines which group are named with prefix or suffix.
(see the precedence table on slide 6)
The highest precedence group takes the appropriate suffix with all other groups
taking the prefix (es), however = or Ξ bonds only take suffix form (ene, yne
respectively.
5-Methyl-3-hexanamine
5-Aminoheptanoic acid
3-Amino-2-butanol
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Amines
Precedence Order of Functional Groups (Descending Order)
Class
Functional group
Prefix
suffix
Carboxylic acids
Cyclic alknes or alkenes with
COOH group
COOH
Aldehydes
Cyclic alknes or alkenes with
CHO group
-CHO
Formyl
al
carbaldehyde
ketone
-C=O
oxo
one
Alcohols
-OH
hydroxy
ol
Amines
-NH2
amino
amine
Ethers
-OR
alkoxy
-
Alkenes and aAlkynes
& =Ξ bonds
-
ene & yne
oic acid
carboxylic acid
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Amines
Naming Of Aromatic Amines
They have common names accepted by the IUPAC system, but if the
benzene ring contain groups of higher priorities (COOH > CHO > C=O
> OH > NH) in this case the amino group is added as a prefix .
NH2
NH2
NH2
NH2
CH3
OH
NO2
N
Pyridine
Aniline
Benzenamine
o-Nitroaniline
p-Toluidine
p-Aminophenol
4-Methyl benzenamine
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Amines
Physical Properties of Amines
1) Boiling point :
 Because they possess a polar N-H bond, primary and secondary
amines are capable of forming intramolecular hydrogen bonds among
their molecules; therefore they have: higher boiling points than alkanes
but lower than alcohols (alcohols form stronger H-bonds than amines).
Tertiary amines can not form H-bonds among their molecules and their
molecules are more branched thus they have the lowest boiling points
among amines.
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Amines
2) Solubility :
 All amines are capable of forming hydrogen bonds with water, alcohol
(hydroxylic solvent) , thus they are soluble in water.
The lower molecular weight amines with up to six carbons show appreciable
solubility in water.
3) Basicity Of Amines
Base strength :
Aromatic amines less basic than aliphatic amines
 Electron donating (releasing) groups on N atom increase the basicity
Electron withdrawing groups decrease the basicity
H3C
N
NH2
NH2
H
CH3
>
H3C
NH2
>
>
O2N
H3C
Most basic
NH2
NH2
Least basic
NH2
NO2
>
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>
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Amines
Preparation Of Amines
1) Alkylation of Ammonia:
OH
RNH3X
NH3 + RX
RNH2
2) Reduction of Nitro groups:
3) Reduction of Nitriles:
H2/Pt
or LiAlH4
4) Reduction of Amides:
R-CN
R-CH2NH2
O
R
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C
NH2
LiAlH4
R-CH2NH2
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Amines
Reaction of Amines
• Salts Formation:
HCl
R-NH2
R-NH3Cl
• Amides Formation:
O
O
R
C
• Imines Formation:
Cl
+
`
R-NH
2
R
`
NR
O
R
C
H
+
• Diazonium Salts Formation:
NH2
`
R-NH
2
R
NaNO2
HCl
H
H3O+/ 
OoC
Diazonium salt
(benzene diazonium chloride)
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C
OH
N2 Cl
+
`
NHR
C
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Amines
Questions
•
•
•
•
Write the structure of p-nitrobenzylamine?
How to prepare ethylamine from acetamide?
Why are aliphatic amines is more basic than aromatic amines?
Select the stronger base from each pair of compounds?
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Amines
Thank You for your kind attention !
Questions?
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