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NITRO DERIVATIVES OF BENZENE

In waste acid of the composition: 0.5% of HNO 3 , 74.5% of H 2 SO 4 , and 25%

of H 2 O, nitrobenzene dissolves to the extent of 0.03%. The solubility varies little

with temperature over the range of 4.4 to 82°C.
The solubility of nitrobenzene in water is given below (Table 30).

TABLE 30

SOLUBILITY OF NITROBENZENE IN WATER

Quantity of nitroben-

Temperature °C zene dissolved, %

4.4 0.08

21.1 0.085

43.3 0.090

71.1 0.095

In aqueous solutions of NaHCO 3 , nitrobenzene dissolves with greater diffi-

culty than in water. The values for 43°C are given below (Table 31):

TABLE 31

SOLUBILITY OF NITROBENZENE IN AQUEOUS SOLUTIONS OF NaHCO 3

Concentrations of aqueous solu- Nitrobenzene dissolved

tions of NaHCO 3 , % %

1 0.024

3 0.023

7 0.020

10 0.018

The thermochemical properties of nitrobenzene are given on pp. 259-262.

Chemical properties...............................

Nitrobenzene is resistant to acids. Bases at certain concentrations and tem-

peratures do not affect nitrobenzene. Only when boiled with NaOH in alcoholic

solution, is nitrobenzene reduced to form azoxybenzene. Nitrobenzene does not

react with Friedel-Crafts reagents and can be used as solvent in Friedel-Crafts

reactions.

The reduction of nitrobenzene may lead to various products, depending on the

reaction conditions and on the reducing agent. The subject is dealt with in detail

in organic chemistry textbooks.

TOXICITY OF NITROBENZENE

The toxicity of nitrobenzene consists primarily in the formation of methaemo-

globine in the blood. It is also toxic for the nervous system and the liver. At

concentrations in air exceeding 5 mg/m

3

it is considered dangerous. Poisoning

by nitrobenzene may be caused either by its direct contact with the skin or when
it is inhaled as vapour. Symptoms of slight poisoning include nausea, headache,