10.2 Process Risk Assessment
243
Table 10.2 Thermal hazard data for the synthesis reaction and work-up of 3-amino-2isopropylthio benzonitrile
Synthesis reaction
Precipitation reaction
Process temperature [ ◦ C]
190
65
Boiling point of reaction mixture [ ◦ C]
200
80
Heat of reaction [kJ/kg] a
−181
−110
Heat capacity [kJ kg −1 K −1 ]
1.9
2
a Per kg of reaction mixture
Table 10.3 Reactivity
interaction matrix of the
chemicals involved in the
synthesis reaction and
work-up of
3-amino-2-isopropylthio
benzonitrile
H + CuCN Na 2 S Cu 2 S
HCN
+
+
3-Chloro-2-isopropylthio aniline
(+)
CuCN
+
Na 2 S
+
Cu 2 S
+
3-Methylpyridine
Methyl ethyl ketone
3-Amino-2-isopropylthio benzonitrile
NaCl
3. Activate stirrer
4. Add 200 kg of CuCN
5. Heat to 100 ◦ C
6. Add 210 kg of 3-methylpyridine
7. Heat to 190 ◦ C and activate the reflux condenser
8. Stir at 190 ◦ C during 10 hr
9. Cool to 65 ◦ C
10. Add 180 kg of methyl ethyl ketone
11. Add a total of 150 kg of Na 2 S continuously over the course of 2 hr at 65 ◦ C.
Each batch produces 290 kg of 3-amino-2-isopropylthio benzonitrile. 224 MJ of heat
in the form of steam is required to heat the reaction mixture from room temperature
(25 ◦ C) to 190 ◦ C.
10.2.2 Definition of Safe Process Conditions (Step 2)
Task: Using the information provided in step 1, define the safe process conditions
for the system under review using the questions below as guidance.