Chapter 7: 7.1 Aromaticity Overview

Question 1

True or False:

Aromatic molecules are especially stable

Answer 1

True

Question 2

In order for a molecule to be aromatic, they must…

Answer 2

1. The compound must obey Huckel’s Rule (number of pi-electrons = 4n + 2)
2. The compound must contain a ‘concentric ring of aligned p orbitals’. Resonance!
3. The compound must be planar (big rings are not planar
4. The molecule must be cyclic

Question 3

What is the “n” in Huckel’s Rule?

Answer 3

An integer

Question 4

Describe:

How to determine Huckel’s Rule

Answer 4

1. Solve for how many pi electrons make something aromatic (4n + 2, where n is an integer)
2. See if structure has that many electrons

Question 5

True or False:

Cyclic molecules with heteroatoms can also be aromatic

Answer 5

True

Question 6

Define:

Heteroatoms

Answer 6

Non-carbon and hydrogen atoms

Question 7

What are the common heteroatoms that you should look out for?

Answer 7

1. Nitrogen
2. Oxygen
3. Sulphur

Question 8

Describe:

Nitrogen heteroatom forms

Answer 8

• sp3 hybridized, donates 2 pi electrons
• sp2 hybridized, donates 0 pi electrons

Question 9

Describe:

Oxygen heteroatom forms

Answer 9

• sp3 hybridized, donates 2 pi electrons

Question 10

Describe:

Sulphur heteroatom forms

Answer 10

• sp3 hybridized, donates 2 pi electrons

Question 11

List:

General Naming Rules for Aromatic Rings

Answer 11

1. Identify and name the longest carbon chain
2. If present, assign stereochemistry (R/S or E/Z)
3. Identify and name any substituents on the carbon chain
4. Give these substituents the appropriate ‘address’
5. Add substituent names as a prefix to the carbon chain
6. Change suffix of the carbon chain if necessary (for functional groups)

Question 12

What aromatic derivative will we be naming in most situations?

Answer 12

Benzene derivatives

Question 13

What is another naming method in aromatic rings?

Answer 13

Ortho, meta, and para

Question 14

Explain:

1. Ortho-
2. Meta-
3. Para-

(Aromatic Ring Naming)

Answer 14

1. 1,2-substitution
2. 1,3-substitution
3. 1,4-substitution

Question 15

Example:

What could 1-chloro-2-methylbenzene also be known as?

Answer 15

ortho-chloromethylbenzene

Question 16

Can aromatic rings be substituents on a carbon chain? When?

Answer 16

Yes
* When the aromatic group is a lower priority than the main carbon chain