Help with nitration??
Answer:
write a mechanism for the reaction. you need the workup in order to obtain your neutral nitrogroup, and under these conditions a second substitution is not possible, so u isolate the mono-product, and let it react again.
Consider what is done between the two nitrations to get a handle on this. I don't know this specific chemistry, so can't go further.
I think NO3 group is Ortho and Pera position directing group. If you will try to Carry out double nitration - nitration in a single step, you will end up with about 66 % ortho and about 33 % pera isomer, - meta will be in small quantity only. That is why you need to block this two positions for the entry of second NO3 group to get meta isomer, and it is acheived by two step reaction in different conditions.
It can be done in a single step by using a strong nitrating agent and a harsh reaction condition. Use conc. HNO3 for nitration or the old method ,i.e., 50% conc. H2SO4 + 50% conc. HNO3 mixture.
Try it.
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