Nitro Compounds: Oil of Mirbane and the Road to Aniline

In the paper

Unit 3, Organic chemistry, carries 17 of the 50 chemistry marks — the heaviest unit in the subject. With eleven chapters sharing them, this one averages a little over one and a half (MEC publishes weights by unit, not by chapter). Nitro compounds are short but very askable: one isomerism trap, one colour test and one reduction table.

MEC scope: Nomenclature and isomerism; Preparation and chemical properties of nitroalkanes and nitrobenzene.

Three ways it is asked:

• Recall: the reagent that turns benzene into nitrobenzene; the colour a secondary nitroalkane gives with HNO₂; the trivial name oil of mirbane.
• Understanding: why AgNO₂ gives a nitroalkane while KNO₂ gives a nitrite; why –NO₂ directs meta; why the α-hydrogen of nitromethane is acidic.
• Application: name the product of reducing nitrobenzene in a stated medium; work out which nitroalkane a given alkyl halide gives; identify an unknown from a Victor Meyer colour.