Question

The preparation of benzene from acetylene can also be said as:
A. Oxidation
B. Polymerization
C. Dehydration
D. Condensation

Answer 1

Hint: Acetylene is a simplest alkyne with chemical formula \[{C_2}{H_2}\]. Chemical formula of benzene is \[{C_6}{H_6}\]. So, if we take 3 molecules of ethyne or acetylene and react under further conditions we get the benzene. Now let us see the complete step by step procedure to get the benzene from acetylene.

Complete step by step solution:
- Acetylene has the formula as \[{C_2}{H_2}\] while benzene has a chemical formula as \[{C_6}{H_6}\].
- Benzene is an organic chemical compound that is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each other.
- We can see that if we take 3 molecules of acetylene and allow them to react under certain conditions we can easily get benzene. Now we will see how to proceed to get the final result.
- Pass the three molecules of ethyne through the red hot Fe tube at 873K. All the three molecules of ethyne undergo cyclic polymerization to form benzene. We can also say that all the three molecules of ethyne undergo condensation or trimerization to form benzene. This method is also called polymerization.

Here, we can see that all the three molecules of ethyne undergo cyclic polymerization to form benzene.

So, from above we can conclude that benzene can be formed from acetylene by the process of polymerization.

Note: Remember that apart from the above listed process benzene can also be prepared by aromatic acids through decarboxylation reaction. We can also prepare benzene from phenol as well through diazonium salt intermediate.