AMINES AND AMIDES

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They are derivatives of ammonia where one or more hydrogen atoms have been replaced by alkyl or aryl groups e.g. RNHz, R2NH.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.

 

  1. Primary amine with one alkyl group e.g. RNH2 or

R                      or                     CH3

H          N          H                      H          N          H

  1. Secondary amine with 2 alkyl groups e.g. R2NH or

R                      CH3

R          N    or     CH3      N        H

H

  1. Tertiary amine with 3 alkyl groups e.g. R3N or

R                                             CH3

R1      N        R11    or             CH3          N      CH3

Trimethyl amine

PHYSICAL PROPERTIES

  1. They can dissolve in water.
  2. They are gases and liquid.
  3. They have fishy odour.

 

CHEMICAL PROPERTIES

  1. As bases they neutralize acids.
  2. They dissociate/ionize in water e.g. CH3NH2 + H2O CH3NH3++ OH

 

USES

  1. Used in making nylon
  2. They can also be used in making polyamide.

 

EVALUATION

  1. State two (2) physical properties and two (2) chemical properties of amine.
  2. 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.

See also  COVALENT BONDING - SINGLE BONDS

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. CH3COONH              CH3CONH2 + H2O

 

PHYSICAL PROPERTIES

  1. Only methanamide is a liquid while others are solid.
  2. They have high melting point and high boiling point.

 

CHEMICAL PROPERTIES

  1. Amide can be hydrolysed in the presence of alkali and mineral acid e.g.

CH3CONH2  +  H2O          CH3COOH + NH3

  1. 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

  1. Used in the preparation of amines.
  2. Used in making synthetic resins and plastics.
  3. 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 200C.

H2CO3               CO(NH2)2

 

See also  NATURAL AND SYNTHETIC POLYMERS

OH                               NHz

 

O      C                              O      C

 

OH                           NHz

Carbonamide/urea

 

N.B.:     Urea is produced in our body and excreted in the urine.

 

EVALUATION

  1. Write the structural formula of amide.
  2. Give one different between amine and amide.

 

WEEKEND ASSIGNMENT

1.Tertiary amine is represented as follow

  1. R2NH2    B.  (CH3)2NH       C.R2NH3    D.  R2N

2.Which of the following has fishy odour

  1. alkanoic acid B.  alkanol    C.  amide     D.  amine

3.Amide can be regarded as derivatives of …………

  1. alkanol  B.  policarboxylic acid   C.  monocarboxylic acid  D.  carbonxamide group

4.During the hydrolysis of amides, one of the following is produced.

  1. monocarboxylic acids B.  water    C.  H2SO4    D.NaOH
  2. Carbamide is an example of
  3. 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

CARBOHYDRATES

NATURAL AND SYNTHETIC POLYMERS

Fats and Oils As Higher Esters

ALKANOIC ACIDS

ALKANOLS

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