Benzenes iodonitro

The nitrophenyl radical can react with the iodide ion and solvent, methanol, as well. Transference of hydrogen radical from methyl alcohol to nitrophenyl radical gives rise to nitrobenzene and formaldehyde (CHjOH —> CH2O). Though carefully sought among the products of the reaction, 3-iodonitro-benzene and 4-nitroanisole were lacking. This completely rejects another possible mechanism of the reaction, cine-substitution, which involves the formation of dehydrobenzene as described earlier. 

A mixture of 100 g. (0.73 mole) of p-nitroaniline, 150 g. of concentrated sulfuric acid, and 600 ml. of water is stirred for an hour. The mixture is cooled to 0 and held in the temperature range 0-5 while a solution of 50 g. (0.73 mole) of sodium nitrite in, 150 ml. of water is added slowly with stirring. An excess of sodium nitrite is to be avoided. The cold solution is filtered, and the filtrate is added with stirring to a solution of 200 g. (1.2 moles) of potassium iodide in 650 ml. of water. The precipitated tan solid is removed by filtration and recrystallized from ethanol to give 147 g. (81 ) of p-iodonitro-benzene, m.p. 170-171 . 

Hence, this synthesis can be performed when iodonitro-benzene is obtained from iodobenzene. This can be accomplished by a nitration reaction, where concentrated nitric and sulfuric acids are mixed to produce the nitronium ion C N02) which is the electrophilic reagent that attacks the ring. 

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