Aromatic Directing Effects

Question 1

What is benzene?

Answer 1

Aromatic

Question 2

Why is benzene stable?

Answer 2

Delocalisation of e-

Question 3

What is Huckel’s rule?

Answer 3

For a planar, cyclic compound to be aromatic it must contain uninterrupted p cloud
(4n + 2) p e-

Question 4

Nitration of benzene

Answer 4

Benzene HNO3 Nitro benzene
————->
H2SO4

Question 5

What happens to the stability of alkyl carbocations as energy decreases?

Answer 5

Increases
= tertiary most stable

Question 6

What are dipole moments?

Answer 6

Inductive effect

Question 7

What are resonance effects?

Answer 7

Delocalisation of charge

Question 8

What is electronegativity?

Answer 8

Measure of how “e- attracting” an element is

Question 9

What is the most electronegative element?

Answer 9

Fluorine

Question 10

What does the difference in electronegativity result in?

Answer 10

Polar bond

Question 11

What is permanent electric moment?

Answer 11

Dipole moment

Question 12

What happens to inductive effect as distance increases?

Answer 12

Decreases

Question 13

What is -I?

Answer 13

Withdrawing e-

Question 14

What is +I?

Answer 14

Pushing e-

Question 15

What are the substituents for -I?

Answer 15

CN, NO2, halogens, OCH3, CF3

Question 16

What are the substituents for +I?

Answer 16

Alkyl groups

Question 17

What are resonance effects a result of?

Answer 17

Conjugation of one L.P within π-system

Question 18

What are +R groups?

Answer 18

Donors

Question 19

What are -R groups?

Answer 19

Acceptors
= pull e- towards themselves

Question 20

What do methyl groups do to resonance effect?

Answer 20

Effect orientation of orbitals
= lose resonance effect
= CH3 prevent orbitals in planar

Question 21

What is hyperconjugation?

Answer 21

Mechanism of both e- release + withdrawal

Question 22

What hyperconjugation is known?

Answer 22

C-H + C-C

Question 23

Which hyperconjugation is more important?

Answer 23

C-C

Question 24

What do alkyl substituents do?

Answer 24

Donate e- density via +I + hyperconjugation

Question 25

When is it +I?

Answer 25

Alkyl + hyperconjugation effect

Question 26

When is it -I?

Answer 26

More electronegative

Question 27

When is it +R?

Answer 27

L.P e-

Question 28

When is it -R?

Answer 28

Accept pair of e-

Question 29

When is it ortho/para?

Answer 29

EDG

Question 30

When is it meta?

Answer 30

EWG

Question 31

What are the groups for +R?

Answer 31

Halogens, nitrogen, oxygen + sulphur

Question 32

What are the groups for -R?

Answer 32

CHO, COR, CO2R, COH3, NO2, CN, SO3H

Question 33

When is it a weaker acid?

Answer 33

EDG

Question 34

When is it a stronger acid?

Answer 34

EWG

Question 35

When is it not effective resonance?

Answer 35

p-orbitals don't line up

Question 36

When is R dominant?

Answer 36

When sp/sp2 C

Question 37

What happens when there is a sp3 C?

Answer 37

NO R

Question 38

How can more -R groups be identified?

Answer 38

NMR shifts = gives clue Meta position most e- rich

Question 39

What happens if you have two substituents?

Answer 39

They both have directing effects BUT EDG will win And added X will go ortho/para