Amines

Question 1

How can we use amines to make basic buffer solutions?

Answer 1

By mixing a weak base and a salt of the weak base together

For example:
- Ammonia and ammonium chloride
- Methylamine and methylammonium chloride

Question 2

Why is ammonium chloride a solid at room temp whereas ammonia is a gas?

Answer 2

Ammonium chloride has ionic bonds held in a giant ionic lattice that requires a lot of energy to overcome.

Ammonia is a simple molecular structure with hydrogen bonds that require much less energy to overcome.

Question 3

What are the 3 ways of making amines?

Answer 3

1. Reaction of ammonia with halogenoalkanes (You end up with a mixture of products - primary secondary tertiary and quaternary).
2. Reaction of halogenoalkanes with sodium cyanide and then reduction with hydrogen and a nickel catalyst.
   This method selectively makes primary amines.
   Haloalkane -> nitrile -> primary amine
3. Making phenyl amines
   - Nitration of benzene
   - Reduction of the nitro group using SN/HCL –> protonated phenylamine
   - Add NaOH to deprotonate the amine group

Question 4

How can we prevent polysubstitution from happening in the first method of making amines?

Answer 4

• Excess ammonia (nucleophile)
• Ensure the chloroethane is in limiting.

Question 5

What are amines used for?

Answer 5

In the manufacture of nylon, dyes and drugs

Quaternary ammonium compounds are used to make hair and fabric conditioners

Question 6

How are quaternary ammonium compounds used to make hair and fabric conditioners?

Answer 6

• Both wet hair and wet fabric pick up negative charges on their surface
• The positive charges of the cations are attracted to the negative charge on the wet surface
• The quaternary ammonium compound forms a coating on the wet surface that prevents the build up of static electricity
• This helps keep the surface of the fabric smooth and prevents flyaway hairs.