A2- Amines

Question 1

What is a primary amine?

Answer 1

an amine group bonded to 2 hydrogens and 1 alkyl group

Question 2

What is a secondary amine?

Answer 2

an amine group bonded to 1 hydrogens and 2 alkyl group

Question 3

What is a tertiary amine?

Answer 3

an amine group bonded to 3 alkyl group

Question 4

Why can amines act as bases?

Answer 4

have a lone pair that is able to accept a proton (donate its lone pair)

Question 5

How do you name amines?

Answer 5

1- find parent chain
2- name other groups bonded to Nitrogen, with N infront
3- write groups in alphabetical order and add amine

Question 6

Why are straight chain amines stronger bases than ammonia?

Answer 6

• positive inductive effect pushes electron density towards lone pair
• lone pair is more available to be donated to a proton

Question 7

Which of the following is a stronger base, a primary amine or a tertiary amine? Why?

Answer 7

• tertiary
• greater positive inductive effect
• lone pair is more available to be donated to a H

Question 8

Why are aromatic amines weaker bases than ammonia?

Answer 8

• lone pair is pulled into the delocalised electron system
• lone pair is less available to be donated to a proton

Question 9

How are amines formed through substitution of halogenoalkanes?

Answer 9

react a halogenoalkane with excess NH3, dissolved in ethanol

Question 10

What would happen if there was an excess of halogenoalkane in a substitution with ammonia?

Answer 10

reaction will not stop and will form a secondary or tertiary amine

Question 11

How can amines be formed?

Answer 11

• reduction of nitriles
• substitution with halogenoalkanes
• reduction of nitroarenes

Question 12

What reactant is used to reduce nitriles?

Answer 12

LiAlH4 (lithium aluminium hydrides) dissolved in ether

Question 13

Why is LiAlH4 dissolved in ether and not water?

Answer 13

the presence of water will cause an alcohol to form

Question 14

What 2 steps are involved in forming an amine through reduction? What amines are formed?

Answer 14

1) form RCN
2) reduced to PRIMARY amine using Ni/H2 catalyst

Question 15

What is the overall equation showing the reduction of nitroarenes?

Answer 15

C6H5NO2 + 6[H] -> C6H5NH2 + 2H2O

Question 16

What reactants are used to reduce nitroarenes?

Answer 16

concentrated HCl and Sn catalyst

Question 17

What temperature is needed to reduce nitroarenes?

Answer 17

room temp

Question 18

What are cationic surfactants?

Answer 18

quaternary ammonium salts that have a long hydrocarbon tail

Question 19

How do cationic surfactants act as washing up liquids?

Answer 19

nonpolar tail attracted to grease
polar head attracted to water
allows oil to mix with water

Question 20

What else is produced from reacting a halogenoalkane with excess ammonia?

Answer 20

secondary, tertiary and quaternary salts

Question 21

What is catalytic hydrogenation?

Answer 21

the use of a nickel or Pt catalyst and hydrogen gas to reduce nitriles

Question 22

What are aliphatic amines?

Answer 22

R is an alkyl groups

Question 23

Why is NaOH needed in the reduction of nitroarenes?

Answer 23

proton acceptor

Question 24

What are surfactants?

Answer 24

chemicals that lower the surface tension between immiscible liquids and allow wetting to take place

Question 25

What part of a quaternary ammonium salt is hydrophilic? Hydrophobic?

Answer 25

Hydrophilic: amine
Hydrophobic: hydrocarbons