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2,4,5-Trifluorobromobenzene
Release time：2019-10-09 17:49:00
Product introduction: 2,4,5-trifluorobromobenzene is an important intermediate for the synthesis of drugs. Its price has been high.
Existing synthetic processes and problems: The existing 2,4,5-trifluorobromobenzene is prepared by using 2,4,5-trifluoroaniline as a raw material, diazotizing with nitrite and in excess acid. Produced by a Gartman reaction at low temperatures. Since the diazotization reaction is a rapid and strong exothermic reaction, the conventional reaction process requires a dropping operation, the efficiency is low, and a large amount of by-products and black tar-like substances are still produced, resulting in a low yield of the target product; Due to the need to quickly remove the heat of diazotization reaction, a slow dropping and rapid stirring operation is required, so that the reaction time is long and the reaction process is not easy to control. In addition, a large amount of dilute acid is required during the reaction, and a large amount of waste water and a lower concentration of waste acid are produced after the reaction.
The present technology and features: The technology utilizes the characteristics of high mass transfer and heat transfer of the microstructure reactor to enable efficient and safe diazotization reaction. Its features include:
Instantly mix, fully prevent decomposition of active compounds (diazonium salts).
A higher concentration of acid can be used as a reaction raw material, which reduces the generation of waste acid and wastewater.
This type of reaction can be carried out at room temperature, breaking through the constraints of the traditional diazotization reaction at zero.
The reaction time can be greatly shortened, and the limitation of the conventional dropping of the diazotization reaction is broken.
The time and temperature are precisely controlled during the reaction, which is beneficial to improve the yield and selectivity.
The use of this technology for the diazotization reaction has a greater advantage than the conventional drip tank reaction, the relevant comparison results are shown in Table 1.
| 2,4,5-trifluorobromobenzene made from 2,4,5-trifluoroaniline | Yield | Time/s | temperature/oC | Reduce wastewater | Reduce waste acid |
| Microstructure reactor | 93% | 11.9 | 15~20 | 33% | 38% |
| Conventional reactor | 80% | 1500 | 0~5 | --- | --- |