Aromatic Hydrocarbons PPT Flashcards

1
Q

is the generic term for an aromatic hydrocarbon

A

Arene

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2
Q

is derived by removal of a hydrogen

A

Aryl group

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3
Q

Aromatic compounds undergo what kind of reaction

A

Electrophilic Aromatic Substitution

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4
Q

draw the halogenation reaction and its reactants

A

grade yourself accordingly

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5
Q

draw the nitration reaction and its reactans

A

grade yourself accordingly

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6
Q

has a full or positive charge

A

electrophile

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7
Q

draw the sulfonation reaction and its needed reactants

A

Aromatic compounds undergo

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8
Q

draw the friedel crafts alkylation

A

grade yourself accordingly

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9
Q

draw the friedel crafts acylation

A

grade yourself accordingly

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10
Q

In step 1 of the mechanism, the electrophile reacts with two p electrons
from the aromatic ring to form a what

A

arenium ion

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11
Q

In step 2, a wha is removed and the aromatic system is regenerated

A

proton

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12
Q

generation of arenium ion is what kind of rxn

A

endothermic

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13
Q

The first step requires the loss of aromaticity of the very stable benzene ring, which is highly unfavorable

thus the first step is rate ____

A

determining

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14
Q

second step wherein the ring gains it aromatic substitution is highly

A

exothermic

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15
Q

which has a larger DG‡, first or second step

A

first step

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16
Q

The ring regains its aromatic stabilization, a highly favorable/unfavorable process

A

favorable

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17
Q

Halogenation of benzene requires the presence of a what

A

Lewis acid

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18
Q

A special apparatus is used to perform this reaction

A

fluorination

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19
Q

occurs so rapidly it is hard to stop at
monofluorination of the ring

A

fluorination

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20
Q

is so unreactive that an alternative method must be used

A

iodine

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21
Q

draw the iodination reaction

A

grade yourself accordingly

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22
Q

in nitration, the nitric acid can dissociate to form a what

A

nitronium ion

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23
Q

is the actual electrophile in nitration; it reacts with benzene to form a resonance-stabilized arenium ion

A

nitronium ion

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24
Q

Sulfonation occurs most rapidly using what

A

fuming sulfuric acid

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25
Q

fuming sulfuric acid is made out of

A

conc. sulfuric acid that contains SO3

26
Q

is an equilibrium reaction; all steps are equilibria

A

sulfonation

27
Q

The sulfonation product is favored by use of what kind of H2SO4

A

concentrated or fuming

28
Q

can be accomplished using dilute sulfuric acid

A

desulfonation

29
Q

sulfuric acid with a high concentration of water

A

dilute sulfuric accid

30
Q

another way for desulfonation aside from using dillute sulfuric acid

A

passing steam through the reaction and collecting the volatile desulfonated compound as it distils with the steam

31
Q

in the friedel-crafts alkylation what does the Lewis acid do

A

generate a carbocation electrophile

32
Q

Friedel-Crafts Alkylation is named after

A

Charles Friedel
James M. Crafts

33
Q

probably do not form discreet carbocations but
the primary carbon in the complex develops considerable positive charge

A

primary alkyl halides

34
Q

carbonyl attached to some R group

A

acyl group

35
Q

requires reaction of an acid chloride or acid anhydride with a Lewis acid such as aluminium chloride

A

Friedel-Crafts Acylation

36
Q

acid chlorides are made from what

A

carboxylic acids

37
Q

The electrophile in Friedel-Crafts acylation is an

A

acylium ion

38
Q

also make the ring less reactive to Friedel-Crafts
reaction because they become electron-withdrawing groups upon Lewis acid-base reaction with the Lewis acid catalyst

A

amino groups

39
Q

give groups that usually give poor yields in Friedel Crafts reaction

A

grade yourself accordingly

40
Q

cannot be used in Friedel-Crafts reactions because they do not form carbocations readily

A

aryl and vinyl halides

41
Q

occurs frequently with Friedel-Crafts alkylation because the first alkyl group introduced activates the ring toward further substitution

A

polyalkylation

42
Q

does not occur because the acyl group deactivates the aromatic ring to further substitution

A

polyacylation

43
Q

synthetic application of friedel-crafts acylation

A

Clemmensen reduction

44
Q

Clemmensen reduction reduces C=O to

A

methylene group

45
Q

Clemmensen reduction reduces C=O to

A

methylene group

46
Q

conditions of Clemmensen reduction

A

Zn(Hg) / HCl

47
Q

more reactive than benzene

A

activating groups

48
Q

less reactive than benzene

A

deactivating groups

49
Q

direct future substitution to the o- and p- positions

A

o/p-directors

50
Q

directors direct future substitution to the m position

A

m directors

51
Q

all activating groups are what

A

o/p-directors

52
Q

The halides are also ortho-para directors but are

A

mildly deactivating

53
Q

Strong electron-withdrawing groups such as

A

nitro
carboxyl
sulfonate

54
Q

deactivating o/p directors include

A

Cl and Br

55
Q

activate the ring toward further reaction

A

electron donating groups

56
Q

stabilize the transition state of the first step
of substitution and lead to lower DG‡ and faster rates of reaction

A

electron-donating groups

57
Q

deactivate the ring toward further reaction

A

electron withdrawing groups

58
Q

destabilize the transition state and lead
to higher DG‡ and slower rates of reaction

A

electron-withdrawing groups

59
Q

most electron donating compounds include

A

-NH2
-NR2
-OH
-OR

60
Q

meta directing groups have wha charge

A

partial or positive charge

61
Q

what does o/p directors contribute

A

fourth important resonance form