Write equations for the reaction of p -dichlorobenzene with the following: (a) Br2 and FeBr3 (b)

Write equations for the reaction of p -dichlorobenzene with...

Key Concepts

Electrophilic Aromatic Substitution (EAS)

EAS is a fundamental reaction mechanism in aromatic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. This process preserves the aromaticity of the ring and involves the temporary formation of a non-aromatic sigma complex (or arenium ion), before deprotonation restores the aromatic system.

Activation of Electrophiles via Catalysis

Many EAS reactions require the generation of a strong electrophile, which is often achieved by using catalysts such as Lewis acids (e.g., FeBr3 in halogenation). These catalysts interact with reagents like Br2 or Cl2, polarizing them and facilitating the formation of the electrophilic species necessary for the aromatic substitution.

Mechanisms of Specific EAS Reactions

Different electrophiles are introduced to the aromatic ring under varied conditions. For example, bromination (using Br2/FeBr3) and chlorination (using Cl2/FeCl3) involve the formation of a halonium ion intermediate. Nitration (with HNO3/H2SO4) relies on the generation of the nitronium ion (NO2+), while sulfonation (using H2SO4/SO3) involves the electrophilic species that incorporates a sulfonic acid group.

Substituent Effects and Directing Groups

Existing substituents on an aromatic ring influence both the reactivity and the regioselectivity of further substitutions. Activating, deactivating, ortho/para-directing, and meta-directing effects all play a role in determining where new substituents are introduced. Although groups like chlorine are deactivating, they often direct incoming electrophiles to specific positions (typically ortho and para), a factor that must be considered when predicting the outcomes of multi-substituted aromatic reactions.

Transcript

00:01 Explanation for the given question the question is right equations for the reaction of para dichlorobenzene with the following so structure of para di -chlorobenzine is p is para di -chloro di -chlorobenzine react with we have here regions are br2 and ferric tribromide and next reagent is nitric acid hno3 and sulfuric acid h2catechalist and third region is sulfuric acid h2sop4 and sulfur trioxide and fourth reason is cl2 and ferric chlorate so first we'll draw this structure of rican date is para dichlorobenzene structure of para diuclorobenzene is benzene ring having alternate single endable bones and chlorine attached on the para position cl and cl so this is dichloro substrate attached on benzene rings are both are same chlorine and chlorine that is why it is para dichloro benzene when para di chloro benzene reacts with reacts with first region is br2 and febr3.

02:14 The product formed here is bromine as electrophile here produce electrophile and a take on the atroposition of engineering and formed the product here is and this is on pair of position.

02:50 Are present and both parapar positions.

02:52 So this is orthobrto bromo and rbromo para dichloro benzene.

03:01 And next product will form tis.

03:07 The reactant is same, para dichloro benzene.

03:13 For second reason, this is para position and this is para position.

03:23 This is peri -chloro of benzene.

03:26 When this react with nitric acid and h2s4, here the electrolyte, electrofile formed as a nitro, nitro group that is no2.

03:47 So this will attack on the orthoposition of the benzene drink...