Aromatic Substitution Reaction pt 2

Question 1

Electrophilic aromatic substitution

Answer 1

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

Question 2

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

Answer 2

Iron tribromide (FeBr₃)

Question 3

What is the mechanism for bromination of benzene?

Answer 3

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

Question 4

Substitution is an __________ process (downhill energy)

Answer 4

Exergonic

Question 5

Addition is an _________ process (uphill energy)

Answer 5

Endergonic

Question 6

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

Answer 6

Chlorination

Question 7

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

Answer 7

AlCl₃

Question 8

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

Answer 8

(Fuming) H₂SO₄, Benzene-sulfonic acid

Question 9

______ is the electrophile used in a sulfonation reaction

Answer 9

SO₃

Question 10

All electrophilic substitution reaction have what two steps?

Answer 10

1. A nucleophilic attack
2. A proton transfer

Question 11

What is the mechanism for sulfonation of benzene?

Answer 11

1. Nucleophilic attack
2. Sigma complex
3. Proton transfer

Question 12

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

Answer 12

Nitration, nitrobenzene

Question 13

A _________ is the electrophile used in a nitration reaction

Answer 13

Nitronium (NO₂⁺)

Question 14

What is the mechanism for nitration reaction ?

Answer 14

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

Question 15

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

Answer 15

Amino group

Question 16

Friedel-Crafts alkylation

Answer 16

Installs an alkyl group on an aromatic ring

Question 17

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

Answer 17

Carbocation

Question 18

What is the mechanism for Friedel-crafts alkylation?

Answer 18

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

Question 19

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

Answer 19

Carbocation rearrangement (When its not a primary halide mostly)

Question 20

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

Answer 20

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

Question 21

Friedel-crafts acylation

Answer 21

Installs an acyl group on a benzene

Question 22

__________ is the electrophile used in acylation reaction

Answer 22

Acylium ion (R-C⁺=O)

Question 23

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

Answer 23

Carbocation rearrangment

Question 24

What is the mechanism for friedel-craft acylation?

Answer 24

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

Question 25

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

Answer 25

Aryl ketone

Question 26

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

Answer 26

Zn(Hg)/ HCl, heat

Question 27

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

Answer 27

Carbocation rearrangment

Question 28

Nitration of toulene

Answer 28

In toluene the methyl group activates the ring

Question 29

For the regiochemstry of nitration of toulene the ________ product dominates

Answer 29

Ortho (ortho to methyl group)

Question 30

The methyl group in toluene is a ___________ director

Answer 30

Ortho-product director

Question 31

Ortho-para director

Answer 31

It directs incoming nitro groups into the ortho & para positions

Question 32

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

Answer 32

Activator

Question 33

Induction

Answer 33

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

Question 34

Resonance

Answer 34

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

Question 35

Whenever resonance & induction are in competition _________ wins

Answer 35

Resonacne

Question 36

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

Answer 36

Ortho-para director

Question 37

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

Answer 37

Para

Question 38

All activators are \_\_\_\_\_\_\_\_\_

Answer 38

ortho -para directors

Question 39

A ___________ deactivates a ring into electrophilic aromatic substitution

Answer 39

Nitro group

Question 40

A ______ is a deactivator & is a ________ director

Answer 40

Meta

Question 41

Most deactivators are ________ directors

Answer 41

Meta

Question 42

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

Answer 42

Induction

Question 43

The halogen are ________ directors even though they are deactivators

Answer 43

Ortho-para directors

Question 44

Both activators & deactivators can be classified as what?

Answer 44

Strong, moderate, weak

Question 45

Deactivators except _____ are meta directors

Answer 45

Halogens

Question 46

Strong acitvators

Answer 46

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)

Question 47

Moderate activators

Answer 47

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

Question 48

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

Answer 48

Moderate

Question 49

Alkyl group are ______ activators

Answer 49

Weak

Question 50

Halogens on a benzene are _____ deactivators

Answer 50

Weak

Question 51

Moderate deactivators

Answer 51

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

Question 52

What are the 3 strong deactivators?

Answer 52

NO₂, NR₃ (R=alkyl groups), CX_{3 (}X=halogens)

Question 53

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

Answer 53

Activating

Question 54

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

Answer 54

Para

Question 55

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

Answer 55

Less sterically hindered

Question 56

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

Answer 56

Least sterically hindered position

Question 57

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

Answer 57

Blocking group

Question 58

\_\_\_\_\_\_\_\_\_\_\_\_ is the most common blocking group

Answer 58

Sulfonation (SO₃H)

Question 59

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

Answer 59

Amino group

Question 60

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

Answer 60

Moderate or strongly

Question 61

Nucleophilic aromatic substitution (S_NAr)

Answer 61

When the ring is attacked by a nucleophile

Question 62

What are the 3 criteria for a nucleophilic substitution reaction?

Answer 62

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

Question 63

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

Answer 63

All 3

Question 64

What is the mechanism for a nucleophilic substitution reaction?

Answer 64

1. Nucleophilic attack 2. Meisenheimer complex 3. Loss of Lg

Question 65

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

Answer 65

Acid (H₃O⁺)

Question 66

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

Answer 66

Nucleophilic substitution

Question 67

IN an elimination-addition reaction a _________ can occur using amide (NaNH₂/ NH_3(l) / & H₃O⁺)

Answer 67

Nucleophilic substitution reaction