urbaf2

GENERAL INFORMATION ON NITRO COMPOUNDS 181

and the N-O distance has been found to be 1.20 Å. The distance between the

atoms of oxygen in the nitro group is 2.17 Å.

The structure of m- dinitrobenzene, as established by Archer [45], is shown

diagrammatically in Fig. 46.

FIG. 46. Bond distances and angles of m- dinitrobenzene (Archer [45]).

Structures of the simplest compounds containing the nitro group, such as

for example, NO 2 , N 2 O 4 , HNO 3 and NO 2 +, have already been discussed. The N-O

distances for nitromethane are 1.21 Å and the bond angle 127º (Brockway, Beach

and Pauling [46] and Rogowski [47]).

CHEMICAL PROPERTIES OF NITRO COMPOUNDS

PRIMARY, SECONDARY AND TERTIARY NITRO COMPOUNDS

The chemical properties of primary and secondary nitro compounds differ

considerably from those of tertiary nitro compounds. This is due to the presence

of active hydrogen atoms in the first two. The difference appears most clearly when
nitro compounds are treated with alkalis. As long ago as 1872 Meyer [48,48a]

observed that certain nitroparaffins were soluble in sodium hydroxide solutions.

In 1888 Michael [49], and later Nef [50], suggested that the salt formed in the