Directive Influence in Bromination of Bromobenzene
STATEMENT-1 : Bromobenzene upon reaction with gives 1,4-dibromobenzene as the major product.
and
STATEMENT-2 : In bromobenzene, the inductive effect of the bromo group is more dominant than the mesomeric effect in directing the incoming electrophile.
Options
STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is a correct explanation for STATEMENT-1
STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is NOT a correct explanation for STATEMENT-1
STATEMENT-1 is True, STATEMENT-2 is False
STATEMENT-1 is False, STATEMENT-2 is True
Step-by-Step Solution
To evaluate the given statements:
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Analysis of STATEMENT-1:
Bromobenzene undergoes electrophilic aromatic substitution when treated with (which generates in situ as the Lewis acid catalyst to form the electrophile ).
The bromine atom present on the benzene ring is an ortho/para-directing group. Due to steric hindrance at the ortho-position, substitution preferentially takes place at the para-position, yielding 1,4-dibromobenzene as the major product and 1,2-dibromobenzene as the minor product.
Therefore, STATEMENT-1 is True. -
Analysis of STATEMENT-2:
Halogens attached to an aromatic ring exhibit two competing electronic effects:-
A strong electron-withdrawing inductive effect ( effect) through the -bond framework.
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An electron-donating resonance/mesomeric effect ( effect) via delocalization of the lone pair of electrons on the halogen into the -system.
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Reactivity: The inductive withdrawal () is stronger than the mesomeric release (), which causes net deactivation of the benzene ring toward electrophilic attack compared to benzene.
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Directive Influence (Orientation): The incoming electrophile attacks preferentially at the ortho and para positions because the carbocation (arenium ion) intermediates formed by ortho and para attacks are uniquely stabilized by the resonance donation of the halogen's lone pair, giving an especially stable octet-complete contributing structure. Hence, the mesomeric effect () dominates in directing the incoming electrophile, not the inductive effect.
Therefore, STATEMENT-2 is False.
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Conclusion:
STATEMENT-1 is True, STATEMENT-2 is False.
Hence, the correct option is C.