3.11 Amines

Question 1

what is an aliphatic amine?

Answer 1

• R group attached is an alkyl group

Question 2

what is an aromatic amine?

Answer 2

• contains an aryl group ( benzene or phenyl )

Question 3

how do you name amines

Answer 3

• use longest chain name + amine suffix

Question 4

how would you name CH3NH2

Answer 4

methyl amine

Question 5

how would you name CH3CH2NH2

Answer 5

ethyl amine

Question 6

how would you name CH3NHCH3

Answer 6

dimethylamine

Question 7

give the conditions, type of reaction for reaction of halogenoalkanes with ammonia

Answer 7

• nucleophilic substitution
• excess, hot ethanolic ammonia under pressure

Question 8

how can you prepare an amine from reduction of nitriles?

Answer 8

using LiAlH4 or Ni catalyst

4 [H] per C=N bond

2H2 per C=N bond

Question 9

give the first reaction and conditions for preparation of phenyl amine

Answer 9

• benzene undergoes nitration
• conc nitric acid and conc h2so4
• 25-60 degrees

Question 10

give the reaction and conditions for second step of preparation of phenylbenzene

Answer 10

• reduction of nitrobenzene with hot tin and conc HCl under reflux to form acidic mixture

Question 11

what are the basic properties of amines

Answer 11

• NH3 can accept a proton, acting as an acid
• they can act as bases by donating a lone pair of electrons

Question 12

what is the last step for preparation of phenyl amine

Answer 12

• sodium hydroxide added to acidic reaction to form phenylamine
• seperated via steam distillation

Question 13

how is strength determined of ammonia and amines as bases

Answer 13

• strength depends on ability of lone pairs on electrons on nitrogen atom to accept a proton
• stronger the base, more readily a proton is attracted.

Question 14

what factors affect strength of ammonia and bases

Answer 14

positive inductive effect
• alkyl groups donate electron density to nitrogen atom causing lone pair of electrons to become more available

delocalisation
• presence of aromatic rings such as benzene cause lone pair of electrons on nitrogen atom to be delocalised into benzene ring
• lone pair becomes less available, hence weaker

Question 15

how do cationic surfactants work

Answer 15

1. they are quarternary ammonium salts with a positively charged head and a non-polar tail
2. hydrophobic tail dissolves in grease, while hydrophilic head interacts with water
3. allows them to act as emulsifiers