CSUS - CH06B
Amine & Amide
Instructor:J.T.,
P: 1
Amines are derivatives of ammonia.
1
CH2
3
CH2
NH2
CH2
2
H3C
4
Types of amines:
IUPAC name:
** CA name:
Common name:
* Primary (1° amine )
1-aminobutane
butanamine
n-butylamine
2
CH2
NH
CH3
CH2
1
H3C
3
Types of amines:
IUPAC name:
* CA name:
Common name:
Secondary (2° amine)
methylaminopropane
N-methylpropanamine
methylpropylamine
2
H3C
N
CH2
1
Types of amines:
IUPAC name:
* CA name:
Common name:
CH3
CH3
tertiary (3°amine)
dimethylaminoethane
N,N-dimethylethanamine
ethyldimethylamine
* (1°, 2°,) These prefixes refer to the degree of alkyl substitution (“Primary, "secondary" …") on the
nitrogen that is missing a hydrogen atom.
** CA Name: Chemical Abstract Service
CSUS - CH06B
Amine & Amide
Instructor:J.T.,
P: 2
Brønsted Theory:
An acid is a proton (H+) donor.
A base is a proton acceptor.
HCl + H2O '
Cl:(-)
+ H3O(+)
Acid + Base ' Conj. Base + Conj. acid
******************************************************
H3N: + H2O ' NH4(+) + HO(-)
Base + Acid ' Conj. acid + Conj. base
Protonation:
Example: Pyridine:
+ H+
N
N
H
Water Solubility of Amines:
• Most Amines are insoluble in water.
•
Solubility falls off as the hydrocarbon chains get longer
• Tertiary Amines are the least soluble since they have no Hydrogen bonded to the
Nitrogen that could Hydrogen bond with water molecules.
• Aromatic amines have relatively diminished solubility in water, although they retain their
solubility in other, suitable organic solvents.
Simple Rule:
Low pH
Neural
High pH
R3N+ H
R3N:
R2H-
Will be water soluble
less water soluble
Non- water soluble
In low pH amin gets protonated and becomes better soluble, in high pH it gets
deprotonated and the effect on solubility is opposite.
CSUS - CH06B
Amine & Amide
Instructor:J.T.,
Solubility of amines in water
Classified as
Solubility in Water
General
Formula
R4 N+ , X-
Quarternary amine (4°)
Salt, Very soluble
R NH2
Primary amine
(1°)
Soluble
R2 NH
secondary amine
(2o)
less soluble
R3 N
tertiary amine
(3o)
No Hydrogen bonded to the
Nitrogen that could Hydrogen
bond with water molecules...
Density (g/cm3)
Ammonium Hydroxide (25%)
Aniline
C6H5NH2
Pyridine
C5H5N
diethylamine (C2H5)2NH
n-hexylamine: CH3 (CH2)5NH2
0.90
1.02
0.98
0.71
0.77
P: 3
CSUS - CH06B
Amine & Amide
Instructor:J.T.,
P: 4
Amides:
When you see this functional group, the amide group, you know that you have an amide.
Look for carbon double-bonded to oxygen and single-bonded to nitrogen. The carbon is also
bonded to an alkyl group. The nitrogen is bonded to two other things, perhaps hydrogen,
perhaps alkyl groups.
O
R
C
N
H
H
The amide that results from the acetic acid is acetamide. Using the IUPAC name, that becomes
ethanamide.
O
C
H3C
NH2
Making an amide:
Example:
Ethanoic acid + ammonium carbonate →ammonium ethanoate
2 CH3 COOH + (NH4)2 CO3 → 2 CH3 COONH4 + H2O + CO2
CH3COONH4
+ Δ → CH3 CO NH2 + H2O
CSUS - CH06B
Amine & Amide
Instructor:J.T.,
P: 5
Hydrolysis of amides:
Amides can be decomposed by hydrolysis.
Hydrolysis in Acidic Solution:
The products are the acid form of the carboxylic acid and the conjugate acid of the amine.
2 CH3CONH2 + 2 H2O +H2SO4 + Δ → 2 CH3 COOH + 2NH4+ + SO4=
Hydrolysis in Basic Solution:
The products of the reaction are the conjugate base of the
basic form of the amine.
CH3-CH2-CONH2 + NaOH → CH3-CH2-COO- + Na+ + NH3
carboxylic acid and the
CSUS - CH06B
Amine & Amide
Instructor:J.T.,
P: 6
Azo Coupling :
Azo couplings are important in the production of dyes and pH indicators.
Objective:
Electrophilic Aromatic Substitution, Acidic Azo Dyes
Chemicals:
Sulfanilic acid, phenol , 1-naphthol , 2-naphthol , 96 %
ethanol, 2 N acetic acid , NaNO2
Phenol is acute poisoning by ingestion, inhalation or skin contact may
lead to death. Phenol is readily absorbed through the skin.
Azo dyes are toxic and may cause genetic mutations.
Observations:
alcoholic phenol solution + reagent solution → Lemon-yellow color
alcoholic 2-naphthol solution + reagent solution
→ Orange color
alcoholic 1-naphthol solution + reagent solution
→ intensively orange color
SO3H
H
..
NH2 + H
SO3H
N
H
H
SO3H
NH H + HNO2
H
SO3H
N=N
Diazonium ion
H
CSUS - CH06B
Amine & Amide
Instructor:J.T.,
Reaction with phenol forming acid azo dyes:
SO3H
N=N
+
OH
Diazonium ion
SO3H
N=N
OH
+ H
4-Hydroxyazobenzene-4-Sulfonic acid (Yellow)
Reaction with the naphtholes forming acid azo dyes:
OH
SO3H
N=N
+
Diazonium ion
2-Naphthol
HO
SO3H
N=N
+ H
4-[(2-Hydroxy-1-naphthyl)azo]-benzeneSulfonic acid (Orange)
P: 7