Question

What is formed on aromatisation of heptane?

• A. Benzene
• B. Toluene
• C. Xylene
• D. Ethylbenzene

Hint:

Remember the important aromatisation reactions: \[ \boxed{ \begin{aligned} C_6H_{14} &\rightarrow C_6H_6 \quad (\text{Benzene})\\ C_7H_{16} &\rightarrow C_6H_5CH_3 \quad (\text{Toluene})\\ C_8H_{18} &\rightarrow C_6H_4(CH_3)_2 \quad (\text{Xylene}) \end{aligned} } \] These conversions are frequently asked in examinations.

Answer 1

The Correct Option is B

Concept: Aromatisation is the process in which straight-chain alkanes are converted into aromatic hydrocarbons by heating in the presence of suitable catalysts such as platinum, chromium oxide or aluminium oxide. During aromatisation,

• Cyclisation occurs.

• Dehydrogenation takes place.

• An aromatic ring is formed.
The products formed depend upon the number of carbon atoms present in the alkane.

Step 1: Identify the alkane.
The given compound is \[ \boxed{\text{Heptane }(C_7H_{16}).} \] It contains seven carbon atoms.

Step 2: Apply the aromatisation reaction.
On aromatisation, \[ C_7H_{16} \] undergoes cyclisation and dehydrogenation to produce \[ \boxed{C_6H_5CH_3} \] which is \[ \boxed{\text{Toluene}.} \] The reaction may be represented as \[ C_7H_{16} \longrightarrow C_6H_5CH_3+4H_2. \]

Step 3: Identify the product.
The aromatic compound formed from heptane is \[ \boxed{\text{Toluene}.} \] Hence, \[ \boxed{\textbf{Option (B)}} \] is the correct answer.