Amines

Question 1

Amines

Answer 1

• one or more hydrogens on an ammonia molecule are substituted with another functional group
• Primary = 1 substitution, Secondary = 2 subs, tertiary = 3 subs, Quaternary = 4 subs (forms a positive ion that can make salts with negative ions)
• Amines can act as bases because the NH3 molecule still has a lone pair to form dative bonds. NH3 is more strongly basic than primary aliphatic amines, and aromatic amines are weakest, as the lone pair of electrons is less available
• primary aliphatic amines are produced from reaction of ammonia with halogenoalkanes, reduction of nitriles
• aromatic amines are produced by the reduction of nitro compounds, and are used in dyes

Question 2

Cationic Surfactants

Answer 2

• a positive ammonium ion on the end of a large hydrocarbon chain forms a hydrophillic head while the hydrocarbon is still hydrophobic, making a cationic surfactant

Question 3

Amides

Answer 3

• NH2 group bonded to a carbonyl functional group
• n-substituted amides are formed when one of the hydrogens in the NH2 is substituted for another functional group
• formed by nucleophillic addition/elimination with either acyl chloride or acid anhydride and ammonia

Question 4

Nucleophillic addition/elimination

Answer 4

• ammonia acts as a nucleophile and attacks the slightly positive carbon in the carbonyl group, while the oxygen takes electrons from the double bond to open it up
• the other slightly positive atom takes the electrons from its bond and leaves, so the double bond can close back up and the ammonia substitutes with the other atom

Question 5

Forming an amine - nucleophillic substitution

Answer 5

• Halogenoalkane + ammonia -> amine + Quaternary ammonium salt
• the ammonia acts as a nucleophile and attacks the slightly positive carbon while the slightly negative halogen takes the electrons from its bond and escapes
• as the nitrogen now has 4 bonds it is positive, so another ammonia comes and takes a hydrogen from it forming an amine and a positive ammonium salt, which bonds to the escaped negative halogen ion
• further substitutions can occur so a mix of primary, secondary and tertiary amines are produced

Question 6

Forming an amine- catalytic hydrogenation

Answer 6

• Nitrile + reducing agent (LiAlH4 catalyst) -> Amine

- or nitrile + H2 (nickel catalyst, high temp+ pressure) -> amine