Amines 3.3.11

Question 1

how many hydrogens does ammonia have bonded to nitrogen

Answer 1

3

Question 2

how many hydrogens does a primary amine have bonded to nitrogen

Answer 2

2
1 alkyl group

Question 3

how many hydrogens does a secondary amine have bonded to nitrogen

Answer 3

1 hydrogen
2 alkyl groups

Question 4

how many hydrogens does a tertiary amine have bonded to nitrogen

Answer 4

0 hydrogens
3 alkyl groups

Question 5

what are quaternary ammonium salts used to make

Answer 5

cleaning produces such as shampoo , laundry detergent and washing up liquids

Question 6

what are quaternary salts made up from and what are they attracted to

Answer 6

made up from a positive end and are attracted to negative ions

Question 7

what are the long hydrocarbon tails on quaternary salts called

Answer 7

cationic surfactants

Question 8

how do the cationic surfactants work

Answer 8

The non polar tail is attracted to the oil / grease.
The polar head will be attracted to the water.
This now allows the water and oil to mix and removes grease from clothing , skin and dishes

Question 9

how are cationic surfactants used in fabric softeners and hair conditioner

Answer 9

Have a positive ammonium ion which is attracted to negatively charged fibres and hair . This removes static

Question 10

how do amines acts as a base

Answer 10

Have a lone pair of electrons that allow them to accept a proton and hence act as a base

Question 11

how does a proton bond to an amine

Answer 11

Via a dative covalent bond ( coordinate) . Both electrons in the bond originate from the lone pair on the nitrogen

Question 12

What is the strength of the base dependent on

Answer 12

the availability of the lone pair of electrons on the nitrogen . The higher the electron density the more readily available the electrons are

Question 13

what is electron density dependent on

Answer 13

Electron density on the nitrogen is dependent on the type of group attached to the nitrogen

Question 14

why are aromatic amines the weakest bases

Answer 14

The lone pair on the N is partially delocalised into the benzene ring , leading to a reduction in the electron density on the N atom so weaker base strength

Question 15

what is the order of base strength from weakest to strongest

Answer 15

Aromatic amines > ammonia > primary amines > secondary amines > tertiary amines

Question 16

how do alkyl groups make an amine more basic

Answer 16

Alkyl groups are electron pushing groups so they push electrons towards nitrogen . Electron density at nitrogen increases so lone pair availability is increased ( inductive effect )

Question 17

what are the two ways an aliphatic amine is made

Answer 17

• By reacting a halogenoalkane with excess ammonia ( nucleophilic substitution)
• By reducing a nitrile

Question 18

what is the downside of using a nucleophilic substitution mechanism with excess ammonia to make aliphatic amines

Answer 18

It produces primary amines as well as secondary , tertiary and quaternary salts too so we have an impure product

Question 19

if a large excess of ammonia what is the main product

Answer 19

Primary amine

Question 20

if a large excess of halogenoalkane is used in nucleophilic substitution what is the main product

Answer 20

Quaternary ammonium salt

Question 21

how can a quaternary salt be produced from primary amine in nucleophilic substitution

Answer 21

The amines produced have a lone pair on the N atom and so further react with halogenoalkanes .
This means that the H on the N can be successfully replaced by ally groups from the halogenoalkanes right through to quaternary ammonium salts

Question 22

what is the good thing about using reducing nitriles to make amines

Answer 22

This reaction produces a single product so a pure product is made and has higher atom economy

Question 23

what is the cheapest way to make primary amines in industry

Answer 23

To reduce nitriles using hydrogen gas and a nickel or platinum catalyst

Question 24

what is the catalyst and conditions used for reducing nitriles with hydrogen gas

Answer 24

Catalyst - Nickel
Conditions - high temp and high pressure

Question 25

what is the reaction of reducing nitriles using a nickel catalyst and hydrogen gas called

Answer 25

catalytic hydrogenation

Question 26

why is reducing nitriles using a strong reducing agent and dilute acid not used in industry

Answer 26

Reducing agent LiAlH4 is expensive

Question 27

what is the reaction of reducing nitriles using a strong reducing agent and dilute acid called

Answer 27

Called a reduction

Question 28

what would you use in a reaction if reducing nitriles using a strong reducing agent and dilute acid

Answer 28

Use - LiAlH4 ( reducing agent ) and a dilute acid

Question 29

what are aromatic amines used to make

Answer 29

Dye stuffs and pharmaceuticals

Question 30

how are aromatic amines made

Answer 30

By reducing nitro compounds such as nitrobenzene

Question 31

What are the conditions and reagents needed for reducing nitro compounds to make aromatic amines

Answer 31

conditions : heat under reflux
Reagents : conc HCl , NaOH
catalyst : Sn

Question 32

what is an amide

Answer 32

derivatives of carboxylic acids .
Instead of having -OH like in a carboxylic acid we have an NH2

Question 33

what’s the functional group of an amide

Answer 33

• CONH2

Question 34

what’s the two reaction scheme to preparing amines from nitriles

Answer 34

step 1 : convert halogenoalkane to nitrile by using KCN in ethanol and aq
step 2 : reduce nitrile to amine by using LiAlH4 in ether or by reducing with H2 and using a Ni/ Pt catalyst

Question 35

what’s a disadvantage of the two reaction steps into making an amine from a nitrile

Answer 35

Has a low yield
KCN is toxic