AMINES
It has a functional group of NH2.
GENERAL MOLECULAR FORMULAR/STRUCTURE
It has a general molecular formula of RNH2 or structure of R – N – H
H
PREPARATION:
They are derivatives of ammonia where one or more hydrogen atoms have been replaced by alkyl or aryl groups e.g. RNHz, R2NH.
CLASSIFICATION:
Amines can be classified according to alkyl group.
- Primary amine with one alkyl group e.g. RNH2 or
R or CH3
H N H H N H
- Secondary amine with 2 alkyl groups e.g. R2NH or
R CH3
R N or CH3 N H
H
- Tertiary amine with 3 alkyl groups e.g. R3N or
R CH3
R1 N R11 or CH3 N CH3
Trimethyl amine
PHYSICAL PROPERTIES
- They can dissolve in water.
- They are gases and liquid.
- They have fishy odour.
CHEMICAL PROPERTIES
- As bases they neutralize acids.
- They dissociate/ionize in water e.g. CH3NH2 + H2O CH3NH3++ OH–
USES
- Used in making nylon
- They can also be used in making polyamide.
EVALUATION
- State two (2) physical properties and two (2) chemical properties of amine.
- Give the classes of amine according to the number of their alkyl groups.
AMIDES
O
It has functional group of –C which is known as carbonamide group.
NH2
STRUCTURE
O H O
CH3 C or H C C
NH2 H N H
H
PREPARATION
– Amide e.g. ethanmide can be derived from ethanoic acid in the presence of ammonia.
O OOO
CH3 C + NH3 C + H2O CH3 – C + NH3 CH3 C +H2O
OH NH2
OH NH2
– Amide is commonly prepared by reacting esters with concentrated aqueous ammonia. E.gCH3COOC2H5 + NH3 Ethanamide CH3CONH2 + C2H5OH
-They can also be prepared by removing a molecule of water from ammonium salt of carboxylic x acids.
e.g. CH3COONH4 CH3CONH2 + H2O
PHYSICAL PROPERTIES
- Only methanamide is a liquid while others are solid.
- They have high melting point and high boiling point.
CHEMICAL PROPERTIES
- Amide can be hydrolysed in the presence of alkali and mineral acid e.g.
CH3CONH2 + H2O CH3COOH + NH3
- In the presence of sodium hydroxide and bromine, amides produce amines with elimination of one carbonyl group.
e.g.CH3CONH2 + Br2 + 4NaOH CH3NH2 + 2NaBr + Na2CO3 + 2H2O
USES
- Used in the preparation of amines.
- Used in making synthetic resins and plastics.
- It can also be used in making fertilizer.
CARBAMIDE/UREA
This is an amide of hydrogen trioxo carbonate (IV) acid. It is produced by compressing CO2 and NH3 at high pressure at 2000C.
H2CO3 CO(NH2)2
OH NHz
O C O C
OH NHz
Carbonamide/urea
N.B.: Urea is produced in our body and excreted in the urine.
EVALUATION
- Write the structural formula of amide.
- Give one different between amine and amide.
WEEKEND ASSIGNMENT
1.Tertiary amine is represented as follow
- R2NH2 B. (CH3)2NH C.R2NH3 D. R2N
2.Which of the following has fishy odour
- alkanoic acid B. alkanol C. amide D. amine
3.Amide can be regarded as derivatives of …………
- alkanol B. policarboxylic acid C. monocarboxylic acid D. carbonxamide group
4.During the hydrolysis of amides, one of the following is produced.
- monocarboxylic acids B. water C. H2SO4 D.NaOH
- Carbamide is an example of
- amine B. alkane C. alkyl D. amide
THEORY
1(a). State two (2) physical properties of amide.
(b). How would you prepare ethanamide from an ester.
2(a). State two (2) chemical properties of amide.
(b). How would you identify an example of amine in the laboratory
See also
NATURAL AND SYNTHETIC POLYMERS
Fats and Oils As Higher Esters