lecture 7

Question 1

how do we activate bromine

Answer 1

bromine
AlCl3
make the Br+ and the Al-

Question 2

bromination: benzene + Br2,,, does the bromine need to be activated

Answer 2

yess

Question 3

nitration: nitric acid and benzene,, does the nitric acid need to be activated

Answer 3

yess

Question 4

how do we activate nitric acid HNO3

Answer 4

HNO3 and H2SO4

Question 5

product of nitric acid activation using H2SO4

Answer 5

NO2+

Question 6

sulfonation: what is needed

Answer 6

activated H2SO4
and benzene

Question 7

what do we need in order to activate H2SO4

Answer 7

H2SO4
H2SO4

Question 8

what is the product of H2SO4 activation

Answer 8

HSO3+

hydrogen sulfite

Question 9

what is needed in a friedel crafts acylation

Answer 9

acyl chloride

Question 10

what is needed for friedel crafts acylation with acyl chloride

Answer 10

acyl chloride
AlCl3

Question 11

describe the friedel crafts acylation with acyl chloride

Answer 11

Cl attacks the AlCl3
AlCl4 is removed
R-C=O remains with resonance forms

the benzene attacks the C+

Question 12

what is friedel crafts acylation about

Answer 12

using carbon as an electrophile

aka we will probably be using a CC+

Question 13

describe an acyl chloride

Answer 13

like an aldehyde but with Cl instead of H

Question 14

what is needed in freidel crafts alkylation

Answer 14

alkyl chloride
tertbutanol

Question 15

describe an alkyl chloride

Answer 15

alkene with a Cl

Question 16

what is needed in friedel crafts alkylation with an alkyl chloride

Answer 16

alkyl chloride
AlCl3

Cl attacks AlCl3 and AlCl4 is removed leaving a CC+ for benzene to attack

Question 17

what is needed for a fridel craft alkylation with alcohol

Answer 17

H+ is needed

the OH attacks this and water is removed

a CC+ is left and a benzene can attack this

Question 18

when an electrophile reacts with benzene,, what is not influenced

Answer 18

there is no influence on what Carbon to attack

the electrophile can bond to any carbon atom

Question 19

how do electron donating groups attached to a benzene affect electrophilic addition reactions

Answer 19

the electrophile doesnt need to be activated

Question 20

why doesnt the electrophile need to be activated when reacting with an aromatic with an e- donating group

Answer 20

the lone pairs in the group donate themselves into the ring system which increases its nucleophilicity

the e- donating groups activated the benzene

Question 21

name some e- donating groups

Answer 21

OH
NH2
CH3
halogens

Question 22

what else do e- donating groups bonded to a benzene do

Answer 22

they can stabilise CC+ in the reactions

this is a good thing
direct electrophiles closer to / opposite themselves

Question 23

electron donating groups on benzene are what directing

Answer 23

ortho
para
directing

Question 24

describe phenol and ONE Br2

Answer 24

no Br2 activation needed

Br is added to the para position on benzene

Question 25

phenol and diluted nitric acid

Answer 25

no activation needed nitro group is added (NO2) either: para 25% ortho. 36% the 2 are structural isomers and have different chemical and physical properties meaning thhey can be separated

Question 26

nitrophenol can be reduced by XXX to give what

Answer 26

can be reduced using H2 and Pd to give amino phenol phenol with NH2

Question 27

acetylation of 4 amino phenol gives

Answer 27

paracetamol

Question 28

what is used to acetylate 4 amino phenol

Answer 28

acetic anhydride

Question 29

describe aniline

Answer 29

benzene with NH2 attached to it

Question 30

describe aniline and Br2

Answer 30

no Br2 activation needed NH2 lone pairs are transported across to attack Br2 from the para position the Br then takes a H and the e- are transported back to the NH2+ to neutralise it. this gives 4bromo aniline and HBr

Question 31

aniline + phenol with excess Br2 products

Answer 31

Br in ortho and para positions ortho + para directing

Question 32

what type of directing are ED groups OH, NH2, halogens, CH3 etc

Answer 32

ortho para directing their e- densities help stabilise the CC+ formed

Question 33

difference between electron donating substituents

Answer 33

OH and NH2 lone pairs activate benzene CH3 doesnt activate benzene

Question 34

benzene and CH3

Answer 34

toluene

Question 35

toluene and Br2

Answer 35

needs activation using a lewis acid (Ae-) Br2 and AlCl3 Br goes ortho : 60% meta : 5% para : 35%

Question 36

why does toluene and activated Br2 give mostly ortho and para additions

Answer 36

ortho and para = tertiary CC+ meta = secondary CC+ less stable and therefore formed less. its formation is not energetically favoured

Question 37

toluene and nitric acid

Answer 37

nitric acid needs activation (H2SO4) gives nitro toluene (NO2) gives: ortho: 55% meta: 5% para: 40%

Question 38

phenol and NaOH with CO2 reaction description : aspirin formation

Answer 38

removes most acidic proton (OH) this activates the phenol at the O is now O- Co2 can react even tho its a bad electrophile aromaticity is then regenerated by removing a proton then OH is acetylated to give aspirin (sodium salicylate)

Question 39

toluene and H2SO4 then NaCl

Answer 39

toluene sulfonation - H2SO4 is activated - goes in ortho + para positions (SO3H) - NaCl : removes the H in SO3H and forms SO3Cl in the ortho and para positions

Question 40

electron withdrawing groups on benzene examples

Answer 40

CF3 NO2 C triple N COOR CHO SO3R

Question 41

trifluoro toluene description

Answer 41

toluene but with F instead of Hs on the CH3

Question 42

trifluoro toluene and HNO3

Answer 42

needs to be activated (H2SO4) NO2 is directed to go to the meta position by CF3

Question 43

why are e- withdrawing groups on benzene meta directing

Answer 43

so the CC+ and its resonance structures are far from the group itself a CC+ next to an e- withdrawing group will remove even more e- density making it even more unstable meta substitution

Question 44

why are ortho and para substitutions not favoured with e- withdrawing groups (NO2, CF3, COOR, CHO, SO3R, CtripleN)

Answer 44

unfavourable as its resonance structures are destabilised when the CC+ is near the EW substituent

Question 45

ED groups are

Answer 45

ortho para directing ortho + para substitutions due to favourable tertiary CC+ formations during resonance

Question 46

EW groups are

Answer 46

meta directing meta substitutions due to unfavourable interactions when the CC+ is near the EW substituent