Benzene is aromatic, with delocalized $$\\pi$$ electrons over the ring.

Question 1

Which statement best describes the type of reaction benzene undergoes with bromine ($$Br_2) in $$the presence of $$FeBr_3$$?

Accepted Answer

Benzene undergoes a substitution reaction, replacing a hydrogen atom with a bromine atom.

Question 2

What is the role of $$FeBr_3 in $$the benzene halogenation reaction?

Accepted Answer

It acts as a catalyst to generate the electrophilic bromine species.

Question 3

Which of the following is the correct product when benzene reacts with $$Cl_2 in $$the presence of $$FeCl_3$$?

Accepted Answer

Chlorobenzene ($$C_6H_5Cl)$$

Question 4

In a Friedel-Crafts alkylation, which reagent is required along with benzene and an alkyl halide?

Accepted Answer

$$AlCl_3$$

Question 5

What is the major product when benzene reacts with $$CH_3CH_2Cl$$ and $$AlCl_3$$?

Accepted Answer

Ethylbenzene ($$C_6H_5CH_2CH_3)$$

Question 6

Which of the following best explains why benzene is uniquely stable?

Accepted Answer

Benzene is aromatic, with delocalized $$\pi$$ electrons over the ring.

Question 7

A student mixes benzene with $$CH_3CH_2Br$$ and $$AlBr_3. $$What is the expected product?

Accepted Answer

Ethylbenzene ($$C_6H_5CH_2CH_3)$$

Question 8

Which of the following is a necessary condition for a Friedel-Crafts alkylation to occur?

Accepted Answer

A Lewis acid catalyst such as $$AlCl_3$$ must be present.

Question 9

What is the missing reagent in the following reaction: $$C_6H_6 + \text{?} \xrightarrow{$$AlBr_3$$} C_6H_5CH_2CH_3$$?

Accepted Answer

$$CH_3CH_2Br$$

Question 10

A chemist wants to synthesize tert-butylbenzene from benzene. Which reagents should be used?

Accepted Answer

$$(CH_3$)_3CCl$$ and $$AlCl_3$$

Question 11

Which of the following is a correct summary of the catalyst and reagent required for benzene halogenation?

Accepted Answer

Halogen ($$X_2) $$and $$FeX_3$$

Question 12

During a Friedel-Crafts alkylation, what is the function of $$AlCl_3$$?

Accepted Answer

It acts as a Lewis acid, generating a carbocation from the alkyl halide.

Question 13

Which of the following reactions will NOT occur under Friedel-Crafts alkylation conditions?

Accepted Answer

Benzene + $$CH_3CH_2OH$$ + $$AlCl_3$$

Question 14

A student performs a benzene halogenation with $$Br_2$$ and $$FeBr_3. $$What is the major product?

Accepted Answer

Bromobenzene ($$C_6H_5Br)$$

Question 15

Which of the following best describes the difference between benzene halogenation and Friedel-Crafts alkylation?

Accepted Answer

Halogenation replaces a hydrogen with a halogen; alkylation replaces a hydrogen with an alkyl group.

Question 16

If benzene reacts with $$2-$$bromo-$$2-$$methylpropane and $$AlBr_3$$, what is the product?

Accepted Answer

tert-butylbenzene ($$C_6H_5C(CH_3$)_3)$$

Question 17

Which of the following is a common misconception about benzene reactions?

Accepted Answer

Benzene undergoes addition reactions with halogens.

Question 18

A chemist wants to prepare ethylbenzene. Which combination of reagents and catalyst should be used?

Accepted Answer

Benzene, $$CH_3CH_2Cl$$, and $$AlCl_3$$

Question 19

Which of the following is the correct balanced equation for the halogenation of benzene with chlorine?

Accepted Answer

$$C_6H_6 + Cl_2$ \xrightarrow{$$FeCl_3$$} C_6H_5Cl + HCl$$

Benzene Substitution Reactions: Halogenation and Friedel-Crafts Alkylation

Study Guide - Practice Questions