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Arrange in order of decreasing trend towards ES (electrophilic substitution) reactions: Chlorobenzene (I), Benzene (II), Anilinium chloride (III), Toluene (IV)

$ (a)\;II > I > III > IV \\ (b)\;III > I > II > IV \\ (c)\;IV > II > I > III \\ (d)\;I > II > III > IV $

1 Answer

An electrophile attacks the region of high electron density.
$-CH_3$ group, having $+I$ effect, increases the electron density in the benzene ring whereas $-Cl $ group having $-I$ effect decrease the electron density the benzene ring. Among,
I is deactivating due to $-I$ effect but $0 /P$ directing due $+M$ effect, where as II is deactivating due to $-I$ effect.
Hence (II) undergo electrophilic substitution reaction less readily than (I).
Therefore the decreasing order is Toluene > Benzene > Chlorbenzene > Anilinium chloride.
$IV > II > I > III$
Hence c is the correct answer.
answered Feb 24, 2014 by meena.p
edited Mar 21, 2014 by balaji.thirumalai

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