Question

Assertion: Benzene on heating with conc. H2SO4 and Conc HNO3 gives nitrobenzene. Reason: Mixture of Conc H2SO4 and Conc HNO3 produces electrophile SO3

a) Out of benzene, m–dinitrobenzene and toluene which will undergo nitration most easily and why? b) Draw resonating structures of chlorobenzene using arrow to show Resonance effect in it.

Benzene is a key compound in organic chemistry and serves as a starting material for synthesizing various derivatives used in industries, such as dyes, plastics, and pharmaceuticals. Due to its aromatic nature, benzene undergoes electrophilic substitution reactions like nitration, sulphonation, halogenation, and Friedel-Crafts alkylation/acylation. These reactions involve the replacement of a hydrogen atom on the benzene ring with a functional group. The reactivity of benzene is influenced by the electron density in its pi system, which makes it susceptible to attack by electrophiles.

(i) Write chemical equation for lab preparation of ethene. (ii) What happens (Give chemical equation involved in each case.) a) when ethene is passed through Br2 water b) Propene reacts with HBr in the presence of peroxide (iii) Convert: a. Ethyne to Benzene b. Benzene to Acetophenone