Large-scale feeding and small-scale testing are completely different in terms of risk.
Large-scale feeding mainly has the problem of superimposed heating effect and many other uncertain problems
In addition, chemical laboratories are only suitable for research and development experiments, especially dangerous or large reactions exceeding kilograms are not suitable for doing in the laboratory.
The fireproof level of the laboratory and the factory workshop are different and cannot be mixed
A certain R&D team thought that the commercially available peroxybenzoic acid was too expensive to prepare it by itself, and first explored the conditions so that it could scale up production in the future
After the first small-scale reaction, the 600mL dichloromethane solution containing about 27g of peroxybenzoic acid was concentrated.
It was intended to be concentrated to 120mL at 40°C under normal pressure.
However, when the volume was concentrated to about 130mL, it happened.
Strong explosion, see Figure 25-31 .
Figure 25-31 The scene after the strong explosion
Large-scale production of extremely dangerous chemical reagents or chemical raw materials has its own unique production safety facilities and management methods, as well as corresponding precautions, which are difficult to achieve in general chemical laboratories under normal circumstances
A research and development team suspected that the commercially available sodium hydrosulfide was of low purity and poor quality, so it carried out large-scale preparation (production) of sodium hydrosulfide in a special gas laboratory;
H 2 S+NaOH→NaHS+H 2 O
Because the simple exhaust gas absorption device in the laboratory is only suitable for small-scale reactions, a large amount of hydrogen sulfide exhaust gas leaked due to incomplete absorption, polluting the entire R&D building and causing emergency evacuation of all personnel in the building
Considering the lower boiling point and toxicity of ethylene oxide, and afraid of its volatilization, a researcher first used a dry ice-acetone bath to cool the reaction solution containing the substrate, ethylene oxide and methanol solvent, and then the extremely low temperature The reaction liquid is added to the oxidation flask and then heated
Due to the extremely cold inside and rapid heating outside, the material structure of the hydrogenation bottle has problems, and its strength drops rapidly as a result, and it cannot withstand the required pressure
When the pressure rises to 30psi, the oxidation bottle explodes, as shown in Figure 25-32
Figure 25-32 Explosion of hydrogenation bottle
Reason analysis: the party’s extremely one-sided thinking → excessive internal cooling and external heating → quenching and heating of the hydrogenation bottle → internal stress change → strength reduction, and the hydrogenation bottle cannot withstand the original prescribed internal pressure and caused an explosion
In addition, ethylene oxide also polymerizes itself