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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