10.2 Process Risk Assessment
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Fig. 10.1 The synthesis route of acibenzolar-S-methyl. Some steps have been redacted, and only
steps relevant for the case study are shown
After completion of the reaction, the copper is separated from the reaction
mixture by adding sodium sulfide. Sodium sulfide and copper chloride react to give
copper sulfide, which precipitates out of solution and is separated by filtration. This
is known as the “work-up” and is carried out to purify the product.
Fig. 10.2 Synthesis reaction (1) and work-up (2) of 3-amino-2-isopropylthio benzonitrile
A known hazard of this process is the formation of hydrogen cyanide (HCN)
during the work-up reaction with sodium sulfide. The following subsections go
through each of the steps of process risk assessment as introduced in Chap. 7.
10.2.1 Scope, System Definition, and Data Collection (Step 1)
For this first step, assume that the following information has already been collected.
10.2.1.1 Scope
The scope of this risk assessment is to assess and reduce the risk related to the
reaction synthesis and work-up of 3-amino-2-isopropylthio benzonitrile during an
early stage of process development.