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Question:

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In the first step due to cooperating Inductive and resonance effect C6H5N2 + will be attached at the ortho position of methyl group for which para position is occupied by Amine group but I am confused with the second reaction with Na2S2O4.

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  • $\begingroup$ Thanku that means C6h5N- is separated and remaing =N got 2 hydrogen as a process of reduction the pdf is not opening $\endgroup$ – Mukul Arora Jul 23 '18 at 15:20
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Sodium dithionite Na2S2O4 (also called sodium hydrosulfite) is a flexible reducing agent that reduces and cleaves ArN=NAr bonds to give ArNH2. It is also good for ArNO2 to ArNH2 and reductions of enones to ketones. Further reading here 1

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  • $\begingroup$ Thanku that means C6h5N- is separated and remaing =N got 2 hydrogen as a process of reduction am i correct in understandingthis way and the pdf is not opening $\endgroup$ – Mukul Arora Jul 23 '18 at 15:25
  • $\begingroup$ You are correct - the other product is aniline. If you are happy with the answer please accept it. PDF should open now $\endgroup$ – Waylander Jul 23 '18 at 15:27
  • $\begingroup$ You are correct. Both nitrogens from the N=N system end up with 2 hydrogens so the reaction product is D and aniline (C6H5NH2) $\endgroup$ – Waylander Jul 23 '18 at 15:46
  • $\begingroup$ When we are going to add C6H5 N2+to the ring it gets add upto that postion otho to methyl grp bcoz 1 ) +M effect of NH2 is equally activating at both ortho and para postion but position ortho to nh2 would lead to decrease in activating affect of +I by CH3 grp so i thought the position ortho to Ch3 is decided in this way.... pls correct me if i am wrong somewhere. $\endgroup$ – Mukul Arora Jul 23 '18 at 15:52
  • $\begingroup$ The directing effect of the -NH2 is stronger than than the effect of the Me group, structure C is never going to be formed as it requires meta addition. Structure D is the only possible answer. Other isomers may be formed but that is beyond the scope of the question, addition to the 2 sides ortho to the NH2 is possible. $\endgroup$ – Waylander Jul 23 '18 at 16:14

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