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500 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

At room temperature the conversion proceeds slowly, whereas it occurs rapidly

on heating. The higher the temperature, the more p- isomers are formed. At 90-100°C

phenoldisulphonic acid is also formed:

Its presence is advisable, as later it will facilitate the nitration process.

Marqueyrol and Loriette [1] investigated the process of phenol sulphonation

with varying sulphuric acid concentration, time and temperature of sulphonation.

Their results are presented below (Table 117).

TABLE 117

SULPHONATION OF PHENOL UNDER VARIOUS CONDITIONS

H 2 SO 4 concentration, %

92

93

94

96

97

100

Time of sulphonation with 93% H 2 SO 4 at 100°C, min

15

30

60

120

240

Per cent of phenol converted

into disulphonic acid

62

66

71

82

91

100

48

65

66

68

68.5

Sulphonation with Ij

93% H 2 SO 4 , temperature °C

Sulphonation time, min

I

75 30 51

75 60 59

150 15 50

150 30 66

150 60 66.5