Chapter 16+17 Flashcards
1
Q
What is Electrophilic Aromatic Substitution (EAS)?
A
Benzene and other aromatic compounds undergo electrophilic substitution rather than addition to retain their aromaticity.
2
Q
What is the general mechanism of EAS?
A
Formation of the Electrophile (E⁺) → Attack on the Benzene Ring → Formation of a Resonance-Stabilized Carbocation → Deprotonation → Restores Aromaticity.
3
Q
What are common electrophilic aromatic substitutions?
A
Halogenation, Nitration, Sulfonation, Friedel–Crafts Alkylation, Friedel–Crafts Acylation.
4
Q
What reagents are used for Halogenation?
A
Cl₂/FeCl₃ or Br₂/FeBr₃.
5
Q
What is the product of Halogenation?
A
Halogenated benzene.
6
Q
What reagents are used for Nitration?
A
HNO₃/H₂SO₄.
7
Q
What is the product of Nitration?
A
Nitrobenzene.
8
Q
What reagents are used for Sulfonation?
A
SO₃/H₂SO₄.
9
Q
What is the product of Sulfonation?
A
Benzene Sulfonic Acid.
10
Q
What reagents are used for Friedel–Crafts Alkylation?
A
R–Cl/AlCl₃.
11
Q
What is the product of Friedel–Crafts Alkylation?
A
Alkylbenzene.
12
Q
What are the limitations of Friedel–Crafts Alkylation?
A
Possible rearrangement, polyalkylation.
13
Q
What reagents are used for Friedel–Crafts Acylation?
A
RCOCl/AlCl₃.
14
Q
What is the product of Friedel–Crafts Acylation?
A
Aryl Ketone.
15
Q
What is the advantage of Friedel–Crafts Acylation?
A
No polyalkylation or rearrangement.
16
Q
How do substituents affect EAS?
A
Activating groups increase reactivity; deactivating groups decrease reactivity.
17
Q
What are examples of activating groups?
A
–OH, –NH₂, –OCH₃, –CH₃.
18
Q
What are examples of deactivating groups?
A
–NO₂, –CF₃, –COOH, –SO₃H.
19
Q
What is Nucleophilic Aromatic Substitution (SNAr)?
A
Occurs when an electron-withdrawing group is present at the ortho or para position relative to the leaving group.
20
Q
What is the mechanism of SNAr?
A
Nucleophile Attack → Forms a Resonance-Stabilized Carbanion → Elimination of Leaving Group → Restores Aromaticity.
21
Q
What reagents are used in SNAr?
A
NaOH, NH₃, NaOR.
22
Q
What are the best activating groups for SNAr?
A
–NO₂, –CN, –COOR.
23
Q
What is the Benzyne Mechanism?
A
For aryl halides lacking an electron-withdrawing group, extreme conditions form a benzyne intermediate.
24
Q
What is the mechanism of the Benzyne Mechanism?
A
Base abstracts a proton, forming benzyne → Nucleophile attacks benzyne → Protonation restores aromaticity.
25
What are the types of carbonyl compounds?
Aldehydes, ketones, carboxylic acids, esters, amides, and acid chlorides.
26
Why are aldehydes more reactive than ketones?
Aldehydes are more reactive due to steric and electronic effects.
27
What is the general mechanism for nucleophilic addition reactions of aldehydes and ketones?
Nucleophile attacks the carbonyl carbon → Tetrahedral intermediate forms → Protonation restores neutral product.
28
What is the product of hydration of aldehydes/ketones?
Geminal Diol.
29
What is formed from the addition of alcohols to carbonyls?
Hemiacetals & Acetals.
30
What is the product of cyanohydrin formation?
Cyanohydrin.
31
What is the product of Grignard addition?
Alcohol.
32
What reagents oxidize aldehydes to carboxylic acids?
KMnO₄, CrO₃, Ag₂O.
33
What reagents reduce carbonyls to alcohols?
LiAlH₄, NaBH₄.
34
What reduces C=O to CH₂?
Clemmensen (Zn/Hg, HCl) and Wolff-Kishner (NH₂NH₂, KOH).
35
What is the reactivity order of carboxylic acid derivatives?
Acid Chlorides > Anhydrides > Esters > Amides.
36
What is the hydrolysis reaction of acid chlorides?
Acid Chlorides + H₂O → Carboxylic Acid.
37
What is the hydrolysis reaction of esters?
Esters + H₂O (H⁺/OH⁻) → Carboxylic Acid & Alcohol.
38
What is the hydrolysis reaction of amides?
Amides + H₂O (Acid/Base) → Carboxylic Acid or Amine.
39
What is the transesterification reaction?
Ester + Alcohol (H⁺) → New Ester + New Alcohol.
40
What is tautomerism?
Keto ↔ Enol forms.
41
What is α-Halogenation?
Enolate + X₂ → α-Halo Carbonyl.
42
What is the product of the aldol reaction?
β-Hydroxy Carbonyl → (Heat) → α,β-Unsaturated Carbonyl.
43
What is the major product of nitration of toluene?
Ortho- and para-nitrotoluene.
44
What is the role of FeBr₃ in bromination of benzene?
FeBr₃ acts as a Lewis acid, generating the electrophile (Br⁺).
45
What happens during Friedel–Crafts alkylation?
Forms a carbocation intermediate and can lead to rearrangements and polyalkylation.
46
What happens during Friedel–Crafts acylation?
Forms a ketone and does not undergo rearrangement or polyacylation.
47
What is the structural requirement for SNAr?
A strong electron-withdrawing group at the ortho or para position.
48
Why do aryl fluorides react faster in SNAr?
Fluorine stabilizes the carbanion intermediate via an inductive effect.
49
Under what conditions does a benzyne intermediate form?
Under strong basic conditions (e.g., NaNH₂, high temperature).
50
How can you distinguish between SNAr and benzyne mechanisms?
Benzyne forms a mixture of regioisomers; SNAr results in selective substitution.
51
What reagent reduces a ketone without affecting a carboxylic acid?
Use NaBH₄.
52
What reagent fully reduces a carboxylic acid to an alkane?
Wolff-Kishner reduction or Clemmensen reduction.
53
What is the synthetic route to convert benzaldehyde into a β-hydroxy ketone?
Use a Grignard reagent with benzaldehyde to form a secondary alcohol, then oxidize it.
54
What is the hydrolysis reaction of methyl benzoate?
Methyl benzoate + H₂O → Benzoic acid + Methanol (acidic or basic conditions)
55
What is the first step in the multi-step synthesis of 2-Phenylpropanoic acid?
Benzene → Acetophenone (Friedel–Crafts acylation, CH₃COCl, AlCl₃)
56
What is the second step in the multi-step synthesis of 2-Phenylpropanoic acid?
Acetophenone → 1-Phenyl-2-propanol (Grignard reaction with CH₃MgBr, then H₃O⁺)
57
What is the final step in the multi-step synthesis of 2-Phenylpropanoic acid?
1-Phenyl-2-propanol → 2-Phenylpropanoic acid (Oxidation using KMnO₄ or CrO₃)
58
Why do carboxylic acids have higher boiling points than alcohols?
They form dimers via strong hydrogen bonding. This results in a larger effective molecular weight and stronger intermolecular forces than alcohols, which only form single hydrogen bonds.
59
What is Electrophilic Aromatic Substitution (EAS)?
Benzene and other aromatic compounds undergo electrophilic substitution rather than addition to retain their aromaticity.
60
What is the general mechanism of EAS?
Formation of the Electrophile (E⁺) → Attack on the Benzene Ring → Formation of a Resonance-Stabilized Carbocation → Deprotonation → Restores Aromaticity.
61
What are common electrophilic aromatic substitutions?
Halogenation, Nitration, Sulfonation, Friedel–Crafts Alkylation, Friedel–Crafts Acylation.
62
What reagents are used for Halogenation?
Cl₂/FeCl₃ or Br₂/FeBr₃.
63
What is the product of Halogenation?
Halogenated benzene.
64
What reagents are used for Nitration?
HNO₃/H₂SO₄.
65
What is the product of Nitration?
Nitrobenzene.
66
What reagents are used for Sulfonation?
SO₃/H₂SO₄.
67
What is the product of Sulfonation?
Benzene Sulfonic Acid.
68
What reagents are used for Friedel–Crafts Alkylation?
R–Cl/AlCl₃.
69
What is the product of Friedel–Crafts Alkylation?
Alkylbenzene.
70
What are the limitations of Friedel–Crafts Alkylation?
Possible rearrangement, polyalkylation.
71
What reagents are used for Friedel–Crafts Acylation?
RCOCl/AlCl₃.
72
What is the product of Friedel–Crafts Acylation?
Aryl Ketone.
73
What is the advantage of Friedel–Crafts Acylation?
No polyalkylation or rearrangement.
74
How do substituents affect EAS?
Activating groups increase reactivity; deactivating groups decrease reactivity.
75
What are examples of activating groups?
–OH, –NH₂, –OCH₃, –CH₃.
76
What are examples of deactivating groups?
–NO₂, –CF₃, –COOH, –SO₃H.
77
What is Nucleophilic Aromatic Substitution (SNAr)?
Occurs when an electron-withdrawing group is present at the ortho or para position relative to the leaving group.
78
What is the mechanism of SNAr?
Nucleophile Attack → Forms a Resonance-Stabilized Carbanion → Elimination of Leaving Group → Restores Aromaticity.
79
What reagents are used in SNAr?
NaOH, NH₃, NaOR.
80
What are the best activating groups for SNAr?
–NO₂, –CN, –COOR.
81
What is the Benzyne Mechanism?
For aryl halides lacking an electron-withdrawing group, extreme conditions form a benzyne intermediate.
82
What is the mechanism of the Benzyne Mechanism?
Base abstracts a proton, forming benzyne → Nucleophile attacks benzyne → Protonation restores aromaticity.
83
What are the types of carbonyl compounds?
Aldehydes, ketones, carboxylic acids, esters, amides, and acid chlorides.
84
Why are aldehydes more reactive than ketones?
Aldehydes are more reactive due to steric and electronic effects.
85
What is the general mechanism for nucleophilic addition reactions of aldehydes and ketones?
Nucleophile attacks the carbonyl carbon → Tetrahedral intermediate forms → Protonation restores neutral product.
86
What is the product of hydration of aldehydes/ketones?
Geminal Diol.
87
What is formed from the addition of alcohols to carbonyls?
Hemiacetals & Acetals.
88
What is the product of cyanohydrin formation?
Cyanohydrin.
89
What is the product of Grignard addition?
Alcohol.
90
What reagents oxidize aldehydes to carboxylic acids?
KMnO₄, CrO₃, Ag₂O.
91
What reagents reduce carbonyls to alcohols?
LiAlH₄, NaBH₄.
92
What reduces C=O to CH₂?
Clemmensen (Zn/Hg, HCl) and Wolff-Kishner (NH₂NH₂, KOH).
93
What is the reactivity order of carboxylic acid derivatives?
Acid Chlorides > Anhydrides > Esters > Amides.
94
What is the hydrolysis reaction of acid chlorides?
Acid Chlorides + H₂O → Carboxylic Acid.
95
What is the hydrolysis reaction of esters?
Esters + H₂O (H⁺/OH⁻) → Carboxylic Acid & Alcohol.
96
What is the hydrolysis reaction of amides?
Amides + H₂O (Acid/Base) → Carboxylic Acid or Amine.
97
What is the transesterification reaction?
Ester + Alcohol (H⁺) → New Ester + New Alcohol.
98
What is tautomerism?
Keto ↔ Enol forms.
99
What is α-Halogenation?
Enolate + X₂ → α-Halo Carbonyl.
100
What is the product of the aldol reaction?
β-Hydroxy Carbonyl → (Heat) → α,β-Unsaturated Carbonyl.
101
What is the major product of nitration of toluene?
Ortho- and para-nitrotoluene.
102
What is the role of FeBr₃ in bromination of benzene?
FeBr₃ acts as a Lewis acid, generating the electrophile (Br⁺).
103
What happens during Friedel–Crafts alkylation?
Forms a carbocation intermediate and can lead to rearrangements and polyalkylation.
104
What happens during Friedel–Crafts acylation?
Forms a ketone and does not undergo rearrangement or polyacylation.
105
What is the structural requirement for SNAr?
A strong electron-withdrawing group at the ortho or para position.
106
Why do aryl fluorides react faster in SNAr?
Fluorine stabilizes the carbanion intermediate via an inductive effect.
107
Under what conditions does a benzyne intermediate form?
Under strong basic conditions (e.g., NaNH₂, high temperature).
108
How can you distinguish between SNAr and benzyne mechanisms?
Benzyne forms a mixture of regioisomers; SNAr results in selective substitution.
109
What reagent reduces a ketone without affecting a carboxylic acid?
Use NaBH₄.
110
What reagent fully reduces a carboxylic acid to an alkane?
Wolff-Kishner reduction or Clemmensen reduction.
111
What is the synthetic route to convert benzaldehyde into a β-hydroxy ketone?
Use a Grignard reagent with benzaldehyde to form a secondary alcohol, then oxidize it.
112
What is the hydrolysis reaction of methyl benzoate?
Methyl benzoate + H₂O → Benzoic acid + Methanol (acidic or basic conditions)
113
What is the first step in the multi-step synthesis of 2-Phenylpropanoic acid?
Benzene → Acetophenone (Friedel–Crafts acylation, CH₃COCl, AlCl₃)
114
What is the second step in the multi-step synthesis of 2-Phenylpropanoic acid?
Acetophenone → 1-Phenyl-2-propanol (Grignard reaction with CH₃MgBr, then H₃O⁺)
115
What is the final step in the multi-step synthesis of 2-Phenylpropanoic acid?
1-Phenyl-2-propanol → 2-Phenylpropanoic acid (Oxidation using KMnO₄ or CrO₃)
116
Why do carboxylic acids have higher boiling points than alcohols?
They form dimers via strong hydrogen bonding. This results in a larger effective molecular weight and stronger intermolecular forces than alcohols, which only form single hydrogen bonds.
