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Organic Chemistry > Aromatic Substitution Reaction pt 2 > Flashcards

Aromatic Substitution Reaction pt 2 Flashcards

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1
Q

Electrophilic aromatic substitution

A

When one of the aromatic protons is replaced by an electrophile & the aromatic moiety is preserved

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2
Q

__________ is used to react with bromine in a bromination reaction to cause the bromine atom to be an electrophile

A

Iron tribromide (FeBr3)

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3
Q

What is the mechanism for bromination of benzene?

A
  1. Formation of iron tribromide
  2. Nucleophilic attack
  3. Sigma complex (Arenium ion)
  4. Proton transfer
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4
Q

Substitution is an __________ process (downhill energy)

A

Exergonic

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5
Q

Addition is an _________ process (uphill energy)

A

Endergonic

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6
Q

____________ of benzene occurs with a lewis acid as aluminum trichloride (AlCl3)

A

Chlorination

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7
Q

The ______ reacts with Cl2 to make it an electrophile (has the same mechanism as bromination)

A

AlCl3

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8
Q

When benzene is treated with __________ a sulfonation reaction occurs where the product is ____________

A

(Fuming) H2SO4, Benzene-sulfonic acid

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9
Q

______ is the electrophile used in a sulfonation reaction

A

SO3

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10
Q

All electrophilic substitution reaction have what two steps?

A
  1. A nucleophilic attack
  2. A proton transfer
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11
Q

What is the mechanism for sulfonation of benzene?

A
  1. Nucleophilic attack
  2. Sigma complex
  3. Proton transfer
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12
Q

When benzene is treated with nitric acid & sulfuric acid a _________ reaction occurs where the product is __________

A

Nitration, nitrobenzene

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13
Q

A _________ is the electrophile used in a nitration reaction

A

Nitronium (NO2+)

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14
Q

What is the mechanism for nitration reaction ?

A
  1. Formation of the nitronium ion (NO2+)
  2. Nucleophilic attack
  3. Sigma complex
  4. Proton transfer
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15
Q

In a nitrration reaction the nitro group can be reduced with Fe or Zn/HCl to form an _________

A

Amino group

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16
Q

Friedel-Crafts alkylation

A

Installs an alkyl group on an aromatic ring

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17
Q

When an alkyl halide react with a lewis acid like Aluminum trichloride (AlCl3) the alkyl halide is converted to a ____________

A

Carbocation

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18
Q

What is the mechanism for Friedel-crafts alkylation?

A
  1. Formation of the carbocation
  2. Nucleophilic attack
  3. Sigma complex
  4. Proton transfer
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19
Q

A friedel-crafts alkylation is only efficient when the substrate can’t undergo ____________

A

Carbocation rearrangement (When its not a primary halide mostly)

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20
Q

What are the things to keep in mind when it comes to friedel-craft alkylation?

A
  1. In the alkyl halide the carbon atom connected to the halogen to the halogen must be Sp3 hybridized
  2. Nitro group are incompatible with a friedel-crafts reaction
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21
Q

Friedel-crafts acylation

A

Installs an acyl group on a benzene

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22
Q

__________ is the electrophile used in acylation reaction

A

Acylium ion (R-C+=O)

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23
Q

Acylium ion are resonance stablizied & can’t be used in ___________________

A

Carbocation rearrangment

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24
Q

What is the mechanism for friedel-craft acylation?

A
  1. Formation for acylium ion
  2. Nucleophilic attack
  3. Sigma complex
  4. Proton transfer
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25
Q

The product of a friedel-craft acylation is an __________ which can be reduced by clemmensen reduction

A

Aryl ketone

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26
Q

Clemmensen reduction uses _____________ to turn the aryl group into an alkyl group ( it removes the carbonyl group)

A

Zn(Hg)/ HCl, heat

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27
Q

Reduction of the aryl group to install an alkyl group is another way to install alkyl groups on a benzene to avoid ______________ & have a mixture of products

A

Carbocation rearrangment

28
Q

Nitration of toulene

A

In toluene the methyl group activates the ring

29
Q

For the regiochemstry of nitration of toulene the ________ product dominates

A

Ortho (ortho to methyl group)

30
Q

The methyl group in toluene is a ___________ director

A

Ortho-product director

31
Q

Ortho-para director

A

It directs incoming nitro groups into the ortho & para positions

32
Q

A methoxy group (OCH3) is a stronger ___________ than a methyl group

A

Activator

33
Q

Induction

A

Suggest that a group is electron withdrawing (would have a + charge in its resonance structures)

34
Q

Resonance

A

Suggest that a group is electron donating (would have a negative charge in its resonance structures)

35
Q

Whenever resonance & induction are in competition _________ wins

A

Resonacne

36
Q

The methoxy group in anisole is an _________________ under a nitration reaction

A

Ortho-para director

37
Q

In nitration of anisole the ______ product is favored over the ortho product due to steric effect

A

Para

38
Q

All activators are _________

A

ortho -para directors

39
Q

A ___________ deactivates a ring into electrophilic aromatic substitution

A

Nitro group

40
Q

A ______ is a deactivator & is a ________ director

A

Meta

41
Q

Most deactivators are ________ directors

A

Meta

42
Q

When there’s competition between resonance & induction when dealing with a halogen, ________ wins

A

Induction

43
Q

The halogen are ________ directors even though they are deactivators

A

Ortho-para directors

44
Q

Both activators & deactivators can be classified as what?

A

Strong, moderate, weak

45
Q

Deactivators except _____ are meta directors

A

Halogens

46
Q

Strong acitvators

A

Are characterized by the presence of a lone pair directly adjacent to the ring (Lone pairs are involved in resonance within the ring where the resonance has a - charge, delocalized in the ring)

47
Q

Moderate activators

A

Exhibit a lone pair that is already delocalized outside the ring (the lone pair is involved with resonance outside the ring)

48
Q

Even though alkyloxy group (OR) has a lone pair directly adjacent to the ring it’s a __________ activator

A

Moderate

49
Q

Alkyl group are ______ activators

A

Weak

50
Q

Halogens on a benzene are _____ deactivators

A

Weak

51
Q

Moderate deactivators

A

Are groups that exhibit a pie bond (double bond) to an electronegative atom & the double bond is adjacent to the ring

52
Q

What are the 3 strong deactivators?

A

NO2, NR3 (R=alkyl groups), CX3 (X=halogens)

53
Q

When two substituents compete with each other to position the incoming group, the stronger ________ group wins

A

Activating

54
Q

For most monosubstituted aromatic rings, the ______ products dominate over the ortho product due to steric effect

A

Para

55
Q

For 1,4-disubstitutied aromatic rings the incoming group is positioned next to the group that is ____________

A

Less sterically hindered

56
Q

For 1,3-disubstituted aromatic ring the incoming group won’t be position between the two substituents instead its placed at the __________ position

A

Least sterically hindered position

57
Q

When you have a monosubstituted reactant and the product is ortho to the substituent then can use a ___________ to force the incoming group to the ortho to substituent

A

Blocking group

58
Q

____________ is the most common blocking group

A

Sulfonation (SO3H)

59
Q

Nitration can’t be formed on a ring that has an _______ group

A

Amino group

60
Q

A Friedel-craft reaction (either alkylation or acylation) can’t occur on a ring that are _______ or ________ deactivators. The ring must either be activated or weakly deactivated for a Friedel-craft reaction

A

Moderate or strongly

61
Q

Nucleophilic aromatic substitution (SNAr)

A

When the ring is attacked by a nucleophile

62
Q

What are the 3 criteria for a nucleophilic substitution reaction?

A
  1. The ring must contain a powerful electron-withdrawing group (usually a nitro group)
  2. The ring must contain a leaving group (usually a halide)
  3. The leaving group must either be ortho or para to the electron-withdrawing group. If the leaving group is meta to the nitro group (or electron-withdrawing group) then the reaction can’t occur
63
Q

For a nucleophilic substitution reaction to occur _____ criteria must be met

A

All 3

64
Q

What is the mechanism for a nucleophilic substitution reaction?

A
  1. Nucleophilic attack
  2. Meisenheimer complex
  3. Loss of Lg
65
Q

When hydroxide (OH) is used as the nucleophile you need an ______ to deprotonate it

A

Acid (H3O+)

66
Q

In an elimination -addition reaction when temp & pressure are high a _______ reaction can occur without a nitro group (Or electron-withdrawing group)

A

Nucleophilic substitution

67
Q

IN an elimination-addition reaction a _________ can occur using amide (NaNH2/ NH3(l) / & H3O+)

A

Nucleophilic substitution reaction

Organic Chemistry (47 decks)

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