Wang Bijia, Cerny Ronald L, Uppaluri Shriharsha, Kempinger Jayson J, Dimagno Stephen G
Department of Chemistry and Nebraska Center for Materials and Nanoscience University of Nebraska, Lincoln, NE 68588-0304, USA ; Tel: 402 472-9895.
J Fluor Chem. 2010 Nov 1;131(11):1113-1121. doi: 10.1016/j.jfluchem.2010.04.004.
Diaryliodonium salts are shown to undergo rapid, fluoride-promoted aryl exchange reactions at room temperature in acetonitrile. Aryl exchange is shown to be exquisitely sensitive to the concentration of fluoride ion in solution; fast exchange is observed as the fluoride concentration approaches a stoichiometric amount at 50 mM substrate concentration. The reaction is slowed, but not halted if benzene is the solvent, indicating that free fluoride ion or a four-coordinate anionic I(III) species may be responsible for the exchange. The fluoride-promoted aryl exchange reaction is general and allows direct measurement of the relative stabilities of diaryliodonium salts featuring different aryl substituents. The aryl exchange reaction may be of practical use for the preparation of hitherto inaccessible diaryliodonium salts, thus it also has implications for labeling radiotracers for molecular imaging with (18)F-fluoride (t(1/2) = 109.7 min).
二芳基碘鎓盐在室温下于乙腈中能发生快速的、氟化物促进的芳基交换反应。研究表明，芳基交换对溶液中氟离子的浓度极为敏感；当底物浓度为50 mM时，随着氟化物浓度接近化学计量数，可观察到快速交换。若以苯为溶剂，反应会减慢，但不会停止，这表明游离氟离子或四配位阴离子I(III)物种可能是交换反应的原因。氟化物促进的芳基交换反应具有普遍性，可直接测定具有不同芳基取代基的二芳基碘鎓盐的相对稳定性。芳基交换反应可能在制备迄今难以获得的二芳基碘鎓盐方面具有实际应用价值，因此它对用（18）F - 氟化物（t(1/2) = 109.7分钟）标记用于分子成像的放射性示踪剂也有重要意义。
