Ch 18 - Electeophilic Aromatic Substitution

Question 0

Halogenation EAS:
H ➡ X

Reagent?

Answer 0

X2/FeX3

Question 1

What is EAS?

Answer 1

Substitute H on benzene with electrophile

Question 2

Nitration EAS:
H ➡ NO2

Reagent?

Answer 2

HNO3/H2SO4

Question 3

Sulfonation EAS:
H➡SO3H

Reagent?

Answer 3

SO3/H2SO4

Question 4

FC Alkylation
H ➡ alkyl group (alkyl benzene)

Reagent?

Answer 4

RCl/AlCl3
•REARRANGEMENTS CAN OCCUR (H shift make more stable E+)
•RCl, or alcohol, alkene

Question 5

FC Acylation
H ➡ O=C-R (ketone)

Reagent?

Answer 5

Acid chloride (RC(=O)Cl)/AlCl3

Question 6

EAS general mechanism?

Answer 6

1) benzene + electrophile➡X=Y-Z+

2) X=Y-Z+ + base ➡ bezene ring restored, EAS Product

Question 7

Electron donating groups?

Answer 7

• R groups - by induction, no resonance

* Z: group bonded to benzene (O or N) - by resonance

Question 8

Electron withdrawing groups?

Answer 8

• Halogens - by induction (electronegativity)

* -Y=Z (EN: Z>Y, Y with full or partial + charge) by induction & resonance

Question 9

Ortho, para directors? Activating or deactivating?

Answer 9

• Z: bonded to benzene (Z=O, N)
• R group (weakest activator)
• Halogens (deactivator)

Question 10

Meta directors? Activating or deactivating?

Answer 10

• Y atom bonded to benzene with full or partial + charge (incl. SO3H, NO2, N(+)R3
• all deactivating

Question 11

With OH, NH2 benzenes:

Reagents of monohalogenation? Polyhalogenation?

Answer 11

• poly - Br2/FeBr3

* mono - just Br2

Question 12

FC rxns do not occur under what conditions?

Answer 12

• meta deactivator on ring

* NH2 on ring (LA/LB ➡ meta)

Question 13

Halogenation of benzene, radical conditions?

Alkyl benzene ➡ benzylic bromide

Answer 13

Br2, light or heat/NBS, light, peroxides

Question 14

Oxidation of alkyl benzenes:
Alkyl benzene (primary or secondary) ➡ carboxylic acid)

Reagents?

Answer 14

KMnO4

Question 15

Reduction of aryl ketones:
C=O ➡ CH2

Reagents?

Answer 15

• Clemmensen - Zn(Hg)/HCl (strong acid)

* Wolff-Kishner - NH2NH2/KOH (strong base)

Question 16

Reduction of NO2 ➡ NH2

Reagents?

Answer 16

• H2, Pd-C
• Fe, HCl
• Sn, HCl

Question 17

Which compounds absorb shortest wavelength of light? Longest wavelength?

Answer 17

• Shortest: most unconjugated (2 or more sigma bonds bet pi bonds)
• Longest: most conjugated (one sigma bond bet pi bonds)