Amines and Amides (CI13.8)

Amines are the organic chemistry equivalents of ammonia, NH3.

Alkyl groups take the place of one, two or three nitrogens…

1. Nomenclature:Higher amines use prefix “amino” e.g 4-aminopentane, CH3CH(NH2)CH2CH2CH3

2. Key properties:Bonding: cf NH3

Lone pair is responsible for:Solubility in H2O / acidic properties /ligand behaviour / electrophilic properties

Solubility. of AminesLike NH3, amines can H-bond, because of this small amines are insoluble in water. Large amines disrupt H-bonding in water.

Amines as Nucleophiles:

R-Cl + NH3 R-NH3+Cl- R-NH2 + H+ + Cl-

Product is an amine, but amines are nucleophiles. So amines undergo addition reactions with halogenoalkanes to form 2ry and 3ry

amides!

R’-Cl + R-NH2

Amides:

Contain functional group

H

R-N-H

3ry amineR’

R-N-H

2ry amine

R-N-R’

R’’1ry amine

H

H-N-H

ammonia

R

R’-N-H

2ry amideR

H

R’-N-H

+

Cl- + H+ + Cl-

H

-CO

N-amide group or “peptide link”

Correct this passage –look for 15 mistakes (at least!!!)

1ry amides are formed by reaction of ammonia with an acyl chloride :

Hydrolysis of amides:

This reaction involves breaking the C=O bond at the carbonyl carbon.

a. acid hydrolysis: forms carboxylate ion and amine

b. alkaline hydrolysis: forms “ammonium” ion and carboxylic acid

Condensation Polymers A condensation reaction is one in which two molecules combine to form a larger molecule with the elimination of a water molecule.

If we react a di-acid with a diamine we get addition polymerisation with the formation of polyesters or nylons.

R-CO

Cl+ R’-NH2

R-CO

N-R’

R2ry amide

+ HCl

1ry amide

+ H2O -CO

OH

O

-C-N-

H

N- H

H+

-N-C-

O

H

O

-C-N-

H

-C-

O O

-C-N-

H

-N-H