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Flashcards in Amines Deck (34)
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1

Why can primary amines act as a base?

What else can it act as?

The N has a lone pair which can accept a proton

A nucleophile as this lone pair can donate to a delta positive C

2

Why can secondary amines act as a base?

What else can it act as?

The lone pair on N can accept a proton

A nucleophile as the lone pair can donate to a delta positive C

3

Why can tertiary amines act as a base?

What else can it act as?

The N has a lone pair which can accept a proton

A nucleophile as this lone pair can donate to a delta positive C

4

Can quaternary ammonium salts act as a base?

Nope

There is no lone pair on the N so it does not react

5

2 ways to prepare an amine?

Nucleophilic substitution

Catalytic hydrogenation

6

What is the equation for the reaction of bromoethane and an excess of NH3?

Why is an excess used?

What is the mechanism?

CH3CH2Br + 2 NH3 —-> CH3CH2NH2 + NH4Br


To avoid further substitution

Nucleophilic substitution

7

What is the disadvantage of forming amines via nucleophilic substitution?

A low yield of primary amine is produced

8

Why is a low yield of primary amine formed for nucleophilic substitution?

A mixture of amine products formed due to product also acting as a nucleophile

9

What is another name for preparing an amine using catalytic hydrogenation?

Reduction of a nitrile

10

What are the two steps for the reduction of a nitrile?

RBr + CN- —-> RCN + Br-

RCN + 2H2 ——> RCH2NH2

11

Overall equation for reduction of a nitrile

RCN + 2H2 ——> RCH2NH2

(Nickel catalyst!)

12

What is the advantage of reducing a nitrile

Why

High yield of product formed

Product does not react with nitrile

13

How to form an aromatic amine

Reduction of nitrobenzene using Sn/ HCl

14

What is the equation for the reduction of nitrobenzene

Nitrobenzene + 6[H] —-> amino benzene + 2H2O

15

What salt is produced from the reduction of nitrobenzene

Why is this formed?

C6H5NH3+Cl-

Reaction is carried out using HCl so amino benzene reacts with HCl

16

What is used to liberate the free amine after the reduction of nitrobenzene

What is the equation?

NaOH

RNH3+Cl- + NaOH —-> amino benzene + H2O + NaCl

17

Are amines strong bases?

Why?

No they’re weak bases

They partially dissociate in water

18

What happens when ammonia acts as a base?

The lone pair on N is donated to accept a proton

19

What is the equation for ammonia and H+

NH3 + H+ —-> NH4+

20

What does the strength of amines as. bases depend on?

The availability of the lone pair

21

Aromatic amines are stronger bases than aliphatic amines. true or false?

False

22

Why Are aromatic amines weaker bases?

The lone pair on N overlaps with the delocalised ring (negative inductive effect)

Making lone pair less available

23

Why are aliphatic amines strong bases?

R group pushes e- towards lone pair on N (positive inductive effect)

Making lone pair on N more available

24

How does chain length affect the positive inductive effect?

Effect increases/ is stronger with increasing chain length

25

C chains release e-

True or false

What is this effect

Positive inductive effect

26

When negative inductive effect occur?

For electronegativity and for benzene ring

27

Describe 2 kinds of negative inductive effect

Benzene ring overlaps with e-

Electronegative atoms withdraw e-

28

What are amines used for?

Making nylon/ drugs

29

What are quaternary ammonium salts used for?

Hair products

30

When are polymers formed?

When monomers join to form a long chain molecule