It is mainly used in circulating cooling water system for scale and corrosion inhibition, such as steel plant, chemical plant, air conditioning and other circulating cooling water systems, which has strong scale inhibition and good corrosion inhibition, and can be operated under high concentration multiplier.
Subsequently, the American DuPont company developed a telomerization reaction with iodine pentafluoride and tetrafluoroethylene to obtain perfluoroalkyl iodide (Figure 17-3).
Although the yield of this reaction is high, the most Iz+5F一+2IFs
The final product is a mixture of SF with different chain lengths, C-CFy+IF y+2I: →SCR CHCECE I+nCF=CFy-CE, CH(CE, CF). 1 (the distribution of n is wider), appropriate Choose a good reaction process to control the reaction
The synthesis of perfluoroalkane iodide should be under process conditions to ensure that n is within the required range (n=2~4) to terminate the reaction, so as to reduce the large amount of undesired high boilers (n>5). There are many other substances used as telogens, and a large number of patents have been published in this research field.
The fluorosurfactants produced by the telomerization method include DuPont in the United States, Ciba-Geigy in Switzerland, Asahi Glass and Daikin in Japan. The product obtained from the telomerization reaction is a mixture of different chain lengths. In this way, fluorocarbon chain hydrophobic groups of different lengths ptfe powder paint can be synthesized. If mixed in an appropriate ratio, the surface activity of the final product can be more exerted.
Using the synthesized perfluoroalkane iodide, a series of functionalized intermediates containing long carbon chain fluoroalkyl groups can be obtained through further chemical transformation. One of the most important intermediates is 2-perfluoroalkyl ethanol. At present, the major foreign companies adopt a stepwise method [7~42], that is, the perfluoroalkyl iodide first reacts with ethylene to form 2- Perfluoroalkyl iodoethane is then hydrolyzed by 2-perfluoroalkyl iodoethane to prepare 2-perfluoroalkylethanol (Figure 17-4).
Our laboratory has invented a one-step method for preparing 2-perfluoroalkylethanol starting from perfluoroalkyl iodoalkanes, and has applied for a Chinese invention patent.
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