Environmental Engineering Reference
In-Depth Information
produced nitrotoluene is separated. The unreacted aliphatic compounds and toluene
was washed away with water and base, and the crude nitrotoluene product includes
55
60 % of o-nitrotoluene, 2
5 % of m-nitrotoluene and 35
40 % of p-nitrotolu-
-
-
-
ene. The yield is 90
95 %. Based on the difference between their boiling points and
melting points, crude distillation and crystallization can be used to separate isomers.
The majority of o-nitrotoluene is separated from the crude nitrotoluene through
vacuum distillation; the most of residual nitrotoluene fractions is distilled and
separated out under vacuum, and
-
final product can be obtained after cooling and
crystallization. The tarry substances with high boiling point was left in the distil-
lation pot. m-Nitrotoluene is contained in the mother liquor after the separation of
p-nitrotoluene, and can be obtained through distillation after repeated accumulation.
The purities of ortho- and para-nitrotoluene are 98 and 99 %, respectively. In China,
manufacturing process with a series of two pot is used, and the temperature of the
main pot is 40
C at the second pot. Substantially, it is
similar to prepare mixed acid as the following: 26
45
°
C, and it is 50
55
°
-
-
-
28 % of nitric acid, 56
-
57 % of
sulfuric acid, 16
18 % of water. Consumptions of raw materials are: 800 kg/t of
toluene (98 %), 470 kg/t of nitric acid (98 %), 450 kg/t of sulfuric acid (92.5 %),
100 kg/t of caustic soda (42 %).
-
4.6.3 Properties and Preparation of 3-Nitrotoluene
4.6.3.1 Properties of 3-Nitrotoluene
Molecular formula: C
7
H
7
NO
2
NO
2
Structure:
CH
3
Molecular weight: 137.14
Oxygen balance:
180.8 % (calculated according to the produced CO
2
)
Content of nitrogen: 10.21 %
−
m-Nitrotoluene is a yellow liquid, insoluble in water, ethanol and ether, with
melting point of 15.1
C, relative density of 1.16, relative
vapor density of 4.72, saturated vapor pressure of 0.13 kPa (50.2
°
C, boiling point of 231.9
°
°
C), partition
coef
cient in octanol/water of 2.4
-
2.45 and
fl
flash point of 101.67
°
C.
References
1. Rongkang S, Yunyang W (1992) The chemistry and technology of nitro compound explosive.
Beijing, p 377
2. Holcomb DE, Dorsey Jr CL (1949) IEC 41:2788
