Question

Which reaction sequence would be best to prepare 3-chloroaniline from benzene?
A.Chlorination, Nitration, Reduction
B.Nitration, Chlorination, Reduction
C.Nitration, Reduction, Chlorination
D.Nitration, Reduction, Acetylation, chlorination, hydrolysis

Answer 1

The nitro group is added in the benzene ring to form the nitrobenzene. Then, nitro benzene is treated with ferric chloride. Since the nitro group is a meta director, we can add Chlorine (Cl) through chlorination. After that, we can reduce the $N{O_2}$ Group to $N{H_2}$ Group.

Complete answer:
First we add nitro group ($N{O_2}$) to the benzene ring to form nitrobenzene through nitration of benzene as nitration of benzene will give nitro benzene as a product. Then, we will treat nitro benzene with ferric chloride in the presence of chlorine gas which will give 3- chloro nitro benzene. In the last step, the reduction of nitro group in 3-chloro nitro benzene by lithium aluminium hydride which will give us 3-chloro aniline.
Since the nitro group is a meta director, we can then add Cl through chlorination. After that, we can reduce the $N{O_2}$ Group to $N{H_2}$ Group.
Here’s a possible synthesis we can consider:

So, the correct reaction sequence that is best to prepare 3-chloroaniline from benzene is Nitration, Chlorination, Reduction.

Therefore, the correct answer is option (B).

Note: An alternative we can consider to prepare 3-chloroaniline from benzene is:
This synthesis involves adding two substituents to the benzene ring. In this case, we need to consider the order of substitution. Cl is an ortho-para director. That means, if Cl is first added to the benzene, the next substituent will be placed in the ortho/para position and that will not work since, in the desired product, $N{H_2}$ is meta to Cl. That means, we need to add Cl in the last. $N{H_2}$ is also an ortho-para director, so that means we can’t add Cl after forming aniline.
3-Nitrochlorobenzene is an organic compound with the formula ${C_6}{H_4}ClN{O_2}$. It is a yellow crystalline solid that is important as a precursor to other compounds due to the two reactive sites present on the molecule.