Basicity and Preparation of Amines

Question 1

why can amines act as bases?

Answer 1

• lone pair of electrons on the nitrogen atom can accept a proton, so amines can act as a base

Question 2

what happens when amine accepts a proton?

Answer 2

• a dative covalent bond

Question 3

what would be formed if CH3CH2CH2NH2 + HCl reacted?

Answer 3

CH3CH2CH2NH3+Cl-

Question 4

what would be formed if 2CH3CH2NH2 + H2SO4 reacted?

Answer 4

(CH3CH2NH3+)2 SO42-

Question 5

how can a primary aliphatic amine be prepared?

Answer 5

step 1: salt formation
- involves the substitution reaction of a haloalkane and ammonia
step 2: amine formation
- aq alkali and a salt to generate the amine

Question 6

what are the conditions to prepare a primary aliphatic amine?

Answer 6

excess ethanolic ammonia
- ethanol as a solvent = prevent substitution of haloalkane by water to produce alcohols
- excess ammonia is used = reduces further substitution of amine group to form secondary or tertiary amines

Question 7

how are secondary aliphatic amines produced?

Answer 7

step 1: salt formation
- haloalkane and primary amine (lone pair on nitrogen atom)
- forms ammonium salt
step 2: amine formation
- ammonium salt and NaOH

Question 8

how are tertiary aliphatic amines produced?

Answer 8

further substitution of secondary amine

Question 9

how can aromatic amines be prepared?

Answer 9

• reduction of nitroarenes using tin and concentrated hydrochloric acid