urbaf2

NITRO DERIVATIVES OF TOLUENE 269

All three isomers are pale yellow substances, with the smell characteristic of

mononitro compounds. They are soluble in most organic solvents. The solubility
of technical MNT in sulphuric acid is shown in Table 46. Due to the presence

of a methyl group, the isomers are much less toxic than nitrobenzene (p. 260).

TABLE 46

SOLUBILITY OF TECHNICAL MNT (MIXTURE OF ISOMERS) IN SULPHURIC ACID (GORST [2])

Concentration of Solubility

sulphuric acid

% H 2 SO 4 at 20°C at 50°C

50 0.04 0.08

75 0.50 0.81

80 1.56 2.09

83 2.73 12.28

88 19.50 20.14

90 33.20 33.90

THERMOCHEMICAL PROPERTIES

Garner and Abernethy [3] give the following thermochemical data for the

isomers of mononitrotoluene :

TABLE 47

HEATS OF COMBUSTION AND HEATS OFFORMATION OF MONONITROTOLUENE ISOMERS

Isomer

Heat of combustion Heat of formation

(at constant volume) kcal/mole

kcal/mole

o- Nitrotoluene (liquid)

m- Nitrotoluene

p- Nitrotoluene

897.0 + 2.0

892.9 + 6.1

888.6 +10.4

From these data Gamer and Abemethy have calculated the heats of nitration

of toluene (Fig. 50 p. 261):

ortho nitration +25.3 kcal/mole

meta nitration +29.4 kcal/mole

para nitration +33.7 kcal/mole

CHEMICAL PROPERTIES

Nitrotoluene is unaffected by acids but oxidized by strong alkalis (e.g. NaOH),

dibenzyl and stilbene derivatives being formed (Bender and Schultz [4], Fischer

and Hepp [5]). Intensely coloured substances appear transiently, to which the