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organic sem 2 > lecture 7 > Flashcards

lecture 7 Flashcards

1
Q

how do we activate bromine

A

bromine
AlCl3
make the Br+ and the Al-

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2
Q

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

A

yess

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3
Q

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

A

yess

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4
Q

how do we activate nitric acid HNO3

A

HNO3 and H2SO4

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5
Q

product of nitric acid activation using H2SO4

A

NO2+

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6
Q

sulfonation: what is needed

A

activated H2SO4
and benzene

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7
Q

what do we need in order to activate H2SO4

A

H2SO4
H2SO4

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8
Q

what is the product of H2SO4 activation

A

HSO3+

hydrogen sulfite

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9
Q

what is needed in a friedel crafts acylation

A

acyl chloride

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10
Q

what is needed for friedel crafts acylation with acyl chloride

A

acyl chloride
AlCl3

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11
Q

describe the friedel crafts acylation with acyl chloride

A

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

the benzene attacks the C+

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12
Q

what is friedel crafts acylation about

A

using carbon as an electrophile

aka we will probably be using a CC+

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13
Q

describe an acyl chloride

A

like an aldehyde but with Cl instead of H

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14
Q

what is needed in freidel crafts alkylation

A

alkyl chloride
tertbutanol

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15
Q

describe an alkyl chloride

A

alkene with a Cl

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16
Q

what is needed in friedel crafts alkylation with an alkyl chloride

A

alkyl chloride
AlCl3

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

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17
Q

what is needed for a fridel craft alkylation with alcohol

A

H+ is needed

the OH attacks this and water is removed

a CC+ is left and a benzene can attack this

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18
Q

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

A

there is no influence on what Carbon to attack

the electrophile can bond to any carbon atom

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19
Q

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

A

the electrophile doesnt need to be activated

20
Q

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

A

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

the e- donating groups activated the benzene

21
Q

name some e- donating groups

A

OH
NH2
CH3
halogens

22
Q

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

A

they can stabilise CC+ in the reactions

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

23
Q

electron donating groups on benzene are what directing

A

ortho
para
directing

24
Q

describe phenol and ONE Br2

A

no Br2 activation needed

Br is added to the para position on benzene

25
Q

phenol and diluted nitric acid

A

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

26
Q

nitrophenol can be reduced by XXX to give what

A

can be reduced using H2 and Pd to give amino phenol

phenol with NH2

27
Q

acetylation of 4 amino phenol gives

A

paracetamol

28
Q

what is used to acetylate 4 amino phenol

A

acetic anhydride

29
Q

describe aniline

A

benzene with NH2 attached to it

30
Q

describe aniline and Br2

A

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

31
Q

aniline + phenol with excess Br2 products

A

Br in ortho and para positions

ortho + para directing

32
Q

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

A

ortho
para directing

their e- densities help stabilise the CC+ formed

33
Q

difference between electron donating substituents

A

OH and NH2
lone pairs activate benzene

CH3 doesnt activate benzene

34
Q

benzene and CH3

A

toluene

35
Q

toluene and Br2

A

needs activation using a lewis acid (Ae-)

Br2 and AlCl3

Br goes
ortho : 60%
meta : 5%
para : 35%

36
Q

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

A

ortho and para = tertiary CC+

meta = secondary CC+
less stable and therefore formed less.

its formation is not energetically favoured

37
Q

toluene and nitric acid

A

nitric acid needs activation (H2SO4) gives nitro toluene (NO2)

gives:
ortho: 55%
meta: 5%
para: 40%

38
Q

phenol and NaOH with CO2 reaction description : aspirin formation

A

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)

39
Q

toluene and H2SO4 then NaCl

A

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
40
Q

electron withdrawing groups on benzene examples

A

CF3
NO2
C triple N
COOR
CHO
SO3R

41
Q

trifluoro toluene description

A

toluene but with F instead of Hs on the CH3

42
Q

trifluoro toluene and HNO3

A

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

43
Q

why are e- withdrawing groups on benzene meta directing

A

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

44
Q

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

A

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

45
Q

ED groups are

A

ortho
para directing

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

46
Q

EW groups are

A

meta directing

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

organic sem 2 (14 decks)

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