continuous supply of which carboxylic acid is required to run correct cycle uninterruptedly
Answers
Explanation:
The Balz–Schiemann reaction, which involves diazotization of the primary aromatic amines followed by fluorinative dediazoniation, could be achieved in preparative scale by carrying the reaction in PPHF, in which case the isolation of the otherwise explosive intermediary diazonium salts is not required (Figure 15). This reaction has been achieved on an industrial scale in a continuous flow reactor, using HBF4 instead of PPHF as the HF source. HBF4 is a relatively safer reagent due to its ease of operation and operational safety. Using this method, large quantities of ortho-difluorobenzene could be prepared from the reaction of ortho-fluoroaniline and sodium nitrite, in 90% yield; the reaction time for the diazotization ranged from 4 to 15 s at 10–25 °C, whereas the fluorodediazoniation of the isolated diazonium salts proceeds in 1–7 min at 140–200 °C.71