IIT JEE , AIEEE Forum - Chemistry , Organic Chemistry

niki_07

why is chlorobenzene much less reactive than alkyl halides? similarly why is aniline a weaker base than aliphatic amine.?i can't find any study material on aromatic in goiit forum . from where to get study material.

i m sure u'll help me afterall we r here to help each other.

catch_arnnie

see, compouds containing halides are subjected to either nucleophilic substitution or elimination reactions. now, in case od chlorobenzene, chlorine will show its +M or +R effect i.e. +ve resonance effect & send its lone pair in resonance with benzene & so, the chlorine-carbon bond will acquire a partial double-bond character, which does not happen in normal alkyl halides. due to this partial double bond, the bond strength increases & chlorobenzene becomes less reactive.

similar is the case for aniline where nitrogen sends its lone pair in resonance & therefore, its basicity decreases...

ramyadiamond

As catch_arnnie has already suggested, the basisity of compounds increases in amines, because it consists of electon releasing groups, which increases the stability of the conjugate acid. While in aniline, the lone pair is in resonance, so it is more difficult to donate its lone pair.

As also fr chlorobenzene, the lone pair takes part in resonance which is a more stabilizing phenomenon hence, it is very less reactive.

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