Aromatics

Question 1

Aromatics

Answer 1

class of compounds that contain six-membered benzene-like rings with three double bonds

Question 2

Huckle’s rule

Answer 2

1. Erich Huckel
2. Aromatic if: planar, monocyclic system of conjugation and contains a total of 4n+2 pi electrons where n is an integer

Question 3

Reaction of Aromatic Compounds

Answer 3

1. Halogenation
2. Nitration
3. Sulfonation
4. Friedel-crafts Alkylation
5. Friedel-crafts Acylation

Question 4

Halogenation

Answer 4

Benzene reacts with Br and Cl in the presence of Lewis acids (AlCl3, FeCl3, or FeBr3)

Question 5

Meta Directors

Answer 5

Look for positive or slightly positive charge induced

Question 6

Ortho and Para Directors

Answer 6

Lone electron pairs

Question 7

Nitration

Answer 7

The nitro substituted product can be reduced by iron, tin, or SnCl2 to yield an ARYLAMINE

Question 8

Sulfonation

Answer 8

• reversible
• favored in strong acid
• Desulfonation: favored in HOT, DILUTE, AQUEAOUS ACID

Question 9

Electrophilic Aromatic Substitution

Answer 9

• The amino group is an activating group and an ORTHO-PARA director
• high reactivity leads to poly substitution
• Mono substitution and Friedl-crafts reaction can be carried out on the corresponding amide rather than the free amine

Question 10

Reactions with Nitrous Acid

Answer 10

1. Primary aliphatic amines
2. Secondary amines
3. Tertiary amines

Question 11

Diazotization Reaction

Answer 11

-primary aryl amines react with nitrous acid to give arenediazonium salts

Question 12

Coupling Reactions

Answer 12

• coupling with PHENOLS take place most rapidly in slightly ALKALINE solution
• coupling with AMINES take place most rapidly in slightly ACIDIC solutions
• PARA or ORTHO
• Azo compounds are reduced to amines (N=N cleavage) by SnCl2

Question 13

Hinsberg Test

Answer 13

• reaction with benzyl sulfonyl chloride

- hydrolysis of sulfonamides result to amines