Solubility Measurement and Recrystallization Process Design for 1,1,2,2,9,9,10,10-Octafluoro[2.2]paracyclophane (AF4) Purification

In this study, a single-step recrystallization process for purifying 1,1,2,2,9,9,10,10-octafluoro[2.2]­paracyclophane (AF4) was investigated. The existing AF4 purification method consists of three steps. Among the steps, methanol washing has a problem of dissolving AF4, so the production yield is around 60%. To improve the yield of AF4 without decreasing its purity, a recrystallization process is suggested, and its feasibility was analyzed by measuring AF4 solubility in each prescreened solvent. Both cooling and antisolvent crystallization were investigated to determine which method would be suitable for the recrystallization process by measuring the purity of the AF4 product. In the results, cooling crystallization with chloroform showed the best performance in terms of 92.31% of the maximum obtainable yield and 99.98% purity in the AF4 purification process. However, antisolvent crystallization showed a high maximum obtainable yield, but very low purity. Therefore, compared to the existing method (60% yield and 99% purity), the suggested cooling recrystallization with chloroform as the solvent is more appropriate for the AF4 purification process.