Question

Fluorobenzene (${C_6}{H_5}F$) can be synthesised in the lab:
A.By heating phenol with $HF$and $KF$
B.From aniline by diazotization followed by heating the diazonium salt with $HB{F_4}$
C.By direct fluorination of benzene with ${F_2}$gas
D.By reacting bromo benzene with $NaF$solution.

Answer 1

First we have to discuss the structure of Fluorobenzene. Therefore, the name suggest it’s a molecule with Fluorine attached to a benzene having a chemical formula of ${C_6}{H_5}F$.The process of synthesising of fluorobenzene contains the process of diazotization.

Complete step by step answer:
The structure of Fluorobenzene as follow:

Now coming to the question we are asked how fluorobenzene can be synthesized. To synthesis fluorobenzene we first need to have aniline. The aniline is then converted into a diazonium salt with the process known as diazotization. In diazotization the aromatic amine like aniline is converted to a diazonium salt. The diazonium salt is having a chemical formula of $R - {N_2}Cl$, R is a benzene ring. After getting diazonium salt we heat it with $HB{F_4}$to get the required product that is fluorobenzene. The reaction is given below:

Hence the answer to this question is option B. From aniline by diazotization followed by heating the diazonium salt with $HB{F_4}$
Note:
We can use Fluorobenzene as a solvent for highly reactive species. It is to be noted that this molecule's melting point is even below that of benzene. The melting point of Fluorobenzene is $-44^oC$. Also the difference in boiling point between the two elements is only $4^oC$. This molecule is more polar than that .