Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.

Hydrocarbons

Short Answer Type

231. What happens when:
Toluene is heated with concentrated sulphuric acid.

461 Views

232. What happens when:
p-xylene is heated with alkaline KMnO₄.

300 Views

233.

What happens when:
Benzene is treated with n-propyl chloride in the presence of anhydrous AlCl₃.

532 Views

Long Answer Type

234.

Discuss the mechanism of electrophilic substitution reactions of benzene?

869 Views

235. Discuss the mechanism of chlorination of benzene.

341 Views

236.

How is benzene converted to nitrobenzene? Give mechanism.

161 Views

237.

How benzene is converted into benzene sulphonic acid? Give its mechanism.
Or
Explain the mechanism of sulphonation of benzene.

524 Views

238.
Discuss the mechanism of Friedel Craft’s reaction.
Or
Discuss the mechanism of Friedel Craft’s alkylation of benzene. Give the mechanism of reaction of benzene within the presence of AlCl_3.Or

How is benzene converted into aceto-phenone? Name the reaction and discuss the mechanism explaining each step.

Or

Give the mechanism of acylation of benzene.

(A) Friedel-Craft alkylation reaction: Benzene reacts with an alkyl halide (R - X) in the presence of anhydrous AICI₃ to form alkyl benzene.

Mechanism. It involves the following steps:

(i) Generation of electrophile:

(ii) Formation of carbocation:

The resonance hybrid structure of the above resonating form can be represented as:

(iii) Transfer of proton from the carbocation to form alkyl benzene:

[B] Friedel-Craft acylation reaction. In acylation of benzene, the hydrogen attached to the carbon atom of the ring gets replaced by the acyl group (RCO-). For example,

Mechanism: It involves following steps:
(i) Generation of electrophile.

(ii) Formation of the carbocation.

The resonance hybrid structure of the above resonating forms can be represented as:

(iii) Proton transfer from the carbocation to form the final product.