urbaf2

NITRO DERIVATIVES OF NAPHTHALENE 429

1,5 and 1,8-isomers are separated only when they are to be used for the manufac-

ture of dyestuffs intermediates. The separation is performed by means of selective

solvents, as for example dichloroethane, which dissolves, the l,8-isomer more readily

than the 1,5-isomer. Analytically, 1,5-dinitronaphthalene can be separated from

the 1,8-isomer by paper chromatography (Franc [24]). The mobile phase consists

of ethyl alcohol, water and acetic acid.

According to Pascal [20], both isomers form solid solutions belonging to Rooze

boom’s system III. When the content of the 1,5-isomer is 22.1%, they have the

lowest melting point, which is 145.5°C (Fig. 107). The other systems examined by

thermal analysis arc tabulated (Table 96).

TABLE 96

EUTECTICS WITH DINITRONAPHTHALENE :

1,5-DINITRONAPHTHALENE

The other % of DNN m.p.

component by weight °C

Author

α− Nitronaphthalene

Picric acid

1,3,5-Trinitronaphthalene

1,3,8-Trinitronaphthalene*

α− Nitronaphthalene

Picric acid

1,3,5-Trinitronaphthalene

8

10

10

27

54.5

113.6

101

165

Pascal [21]

T. Urbanski and Kwiatkowski [25]

Pascal [21]

Pascal [21]

1,8-DINITRONAPTHALENE

(^644) Pascal [21]
43 93
22 88
T. Urbanski and Kwiatkowski [25]
Pascal [21]
1,3,8-Trinitronaphthalene* 52 135 Pascal [21]

• Minimum of Roozeboom system III.
  COMPOSITION OF THE COMMERCIAL PRODUCT
  Patart [19] found that commercial grade dinitronaphthalene, being a mixture
  of isomers, could be obtained by the nitration of naphthalene or α− nitronaphthalene
  with a mixture of the composition:
  HNO 3 8-70%
  H 2 SO 4 0-76%
  H 2 O 16-30%
  As numerous experiments have shown, the weight ratio of the isomers depends
  to a large extent on the nitration temperature.
  According to Pascal [20], at 70°C a mixture of 60% of the 1,8-isomer
  and 40% of the 1,5-isomer is formed. Hodgson and Whitehurst [26] have established
  the 1,5- to 1,8-isomers ratio to be nearly ½, when naphthalene is nitrated at 0-35°C.