Functional Group Chemistry 4

Question 1

Describe amine structure + bonding

Answer 1

N = sp3 with L.P in sp3 orbital

3 groups + L.P = tetrahedral

Question 2

What does the L.P in amines do to the N?

Answer 2

The reactivity of N L.P dominates properties of amins

Question 3

What are the different types of amines?

Answer 3

Primary
Secondary
Tertiary
Quaternary

Question 4

What happens to the boiling points as you go down the different groups of amines?

Answer 4

Decrease = reduced H bonding

Question 5

What happens to the reactivity as you go down the different groups of amines?

Answer 5

Increases = push e- to N = repels L.P due to inductive effect

Question 6

Are NH3 + NH4 good Nu-?

Answer 6

YES

Question 7

What can amines do?

Answer 7

Form H bonds

BUT N-H is weaker than O-H

Question 8

Why is O-H stronger than N-H?

Answer 8

Bigger difference in electronegativity

Question 9

What does the L.P make amines?

Answer 9

Basic + Nu-

Question 10

What to amines react with to form?

Answer 10

Acids to form acid-base salts

Question 11

Describe amin salts

Answer 11

Ionic salts = high M.P
Soluble in H2O
No fishy odour colour
Reversible

Question 12

What is special about amine salts?

Answer 12

Ionic = more soluble in H2O than parent amines

Question 13

What happens to amino acids in neutral solution?

Answer 13

COOH ionised + NH2 protonated

Question 14

What happens to amino acids in acid solution?

Answer 14

COO- protonated

= positive charge

Question 15

What happens to amino acids in base solution?

Answer 15

NH3 ionised

= negative charge

Question 16

How are amines synthesised?

1

Answer 16

Alkyl halide + NaCN —-> RCN

RCN + LiAlH4 + H2O —-> RCH2NH2

Question 17

How are amines synthesised?

Answer 17

Carboxylic acid + SOCl2 + NH3 —-> RCOONH2

RCOONH2 + LiAlH4 + H2O —-> RCH2NH2

Question 18

What do amines react with acid chlorides to produce?

Answer 18

Amides

Question 19

What do amines react with sulfonyl chloride to produce?

Answer 19

Sulphonamides

Question 20

What is the equation for amines + acid chlorides?

Answer 20

RCOOCl + NH3 —-> RCOONH2 + HCl
Solvent = pyridine
RCOOCl + RNH2 —-> RCOONHR + HCl

Question 21

What is the equation for amines + sulfonyl chloride?

Answer 21

RNH2 + SO2ClAr —-> RNHSO2Ar

Need HCl

Question 22

LEARN E1 + E2 MECHANISMS

Answer 22

LOOK ONLINE

Question 23

LEARN SN1 + SN2 MECHANISMS

Answer 23

LOOK ONLINE

Question 24

What does the rate of SN2 reaction depend on?

Answer 24

Nu-
Leaving group
Carbon skeleton
Temperature 
Solvent

Question 25

What does the rate of SN1 reaction depend on?

Answer 25

Carbon skeleton Leaving group Temperature Solvent

Question 26

What are the carbon skeletons for SN1?

Answer 26

``` Methyl = no Primary = no Secondary = moderate Tertiary = excellent ```

Question 27

What are the carbon skeletons for SN2?

Answer 27

``` Methyl = good Primary = good Secondary = moderate Tertiary = no ```

Question 28

What are the cations that normally react with SN1?

Answer 28

t-butyl cation Oxygen-stabilised (oxonium ions) i-propyl cation Nitrogen-stabilised (iminium ions)

Question 29

What is the importance of steric hinderance?

Answer 29

Drives SN1 reactions = stabilises carbocation + hinders approach of the Nu-

Question 30

What happens to stereochemistry in SN1 reactions?

Answer 30

Lose stereo control + obtain racemic mixture if you start with chiral centre

Question 31

What happens to stereochemistry in SN2 reactions?

Answer 31

Invert stereochemistry

Question 32

What solvent does SN1 usually perform in?

Answer 32

Polar protic solvents

Question 33

What solvent does SN2 usually perform in?

Answer 33

Aprotic less polar solvents

Question 34

What effect does the leaving group have in SN1 + SN2?

Answer 34

Plays an important role in both

Question 35

What is the importance of Nu- in SN1?

Answer 35

Isn't important

Question 36

What is the importance of Nu- in SN2?

Answer 36

Good Nu- is essential