The above (C-N) coupling reaction takes place | vedclass

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Question

(B) The coupling reaction between a diazonium salt and an aromatic amine (like $N,N$-dimethylaniline) is highly dependent on the $pH$ of the reaction

Vedclass · Accepted Answer

Intermediate $pH$

Vedclass · Answer

(B) The coupling reaction between a diazonium salt and an aromatic amine (like $N,N$-dimethylaniline) is highly dependent on the $pH$ of the reaction medium.At high $pH$,the diazonium ion is converted into non-electrophilic species like diazohydroxide $(Ar-N=N-OH)$ or diazotate ion $(Ar-N=N-O^-)$,which do not undergo coupling.At low $pH$,the amine group $(-NMe_2)$ of the aromatic amine gets protonated to form an ammonium ion $(-NH^+Me_2)$,which is deactivating and lacks the lone pair of electrons necessary for the nucleophilic attack on the diazonium ion.Therefore,the coupling reaction is most effective at an intermediate $pH$,where the diazonium ion remains electrophilic and the amine remains in its nucleophilic,unprotonated form.

The above $(C-N)$ coupling reaction takes place at

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The correct answer is

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