Quiz - Benzene Derivatives | Electrophilic Substitution of Benzene Derivatives

1

Which of the following reactions is not an electrophilic aromatic substitution?

The formation of nitrobenzene

The formation of benzene sulfonic acid

The formation of benzyne

The formation of bromobenzene

Benzyne is generated by the dehalogenation of 2-bromofluorobenzene by magnesium

2

When considering electrophilic substitution reactions, halides are described as:

Ortho/para directing and activating

Ortho/para directing and deactivating

Meta directing and activating

Meta directing and deactivating

Halides are deactivating groups and ortho/para directing. Please note, deactivating groups are generally meta directing

3

When considering electrophilic substitution reactions, methoxy substituent is described as:

Ortho/para directing and activating

Ortho/para directing and deactivating

Meta directing and activating

Meta directing and deactivating

D ⇒ Donor:
- NH2, OH (strongly activating)
- NHCOR, OR (moderately activating) ⇒ ex: methoxy substituent
- alkyl, aryl (weakly activating)

4

When considering electrophilic substitution reactions, nitro substituent is described as:

Ortho/para directing and activating

Ortho/para directing and deactivating

Meta directing and activating

Meta directing and deactivating

Nitro substituent: NO2

A ⇒ Acceptor:
- N+R3, NO2, CF3, CN, SO3H (strongly deactivating)
- COH, COR, COOH, COOR, CONH2 (moderately deactivating)

5

Which substituent is the strongest activator?

MeO

Br

NH2

NO2

NH(strongly activating) > MeO (moderately activating) > Br (moderately deactivating) > NO2 (strongly deactivating)

6

What is the best synthetic strategy for alkylating bromobenzene in the ortho position?

Friedel-Crafts Acylation followed by a reduction

Sulfonation, Friedel-Crafts Alkylation, Desulfonation

Substitution Nucleophile with halogenoalkane

Friedel-Crafts Alkylation followed by an elimination

Br substituent is ortho/para directing.  Because of the sterics, the para product will be preferred over the ortho product. In order to alkylate bromobenzene in the ortho position, the para position must be locked. A sulfonation of the para positon could be a good strategy: