Abstract
This investigation centers on the preparation of H 18F, K 18F, and KB 18F 4 from reactor-produced [ 18F]fluoride and the efficacy of anhydrous, no-carrier-added H 18F in labeling aryl compounds derived from benzenediazonium-2-carboxylate. It proved possible to prepare KB 18FF 3 only with the addition of considerable KF carrier. A new synthetic route was developed for producing no-carrier-added 2-[ 18F]fluorobenzoic acid, based on the fast reaction between benzenediazonium-2-carboxylate and anhydrous H 18F in benzene solution. If KF carrier is present, however, the primary product is [ 18F]fluorobenzene. An increase in yield of 18F by 96% is found by irradiating aqueous, rather than dry, 6LiOH·H 2O (96% enriched). The yield of 2-[ 18F]fluorobenzoic acid is 32% of the radioactivity distilled and represents an overall radiochemical recovery of 15% of 18F activity eluted from an Al 2O 3 column with cone. NH 4OH. The total processing time from end of irradiation is 90–95 min. Non-radioactive reactions were carried out with macro quantities of anhydrous HF gas, aqueous HF solution, and anhydrous HF distilled from KF and H 2SO 4. With the aqueous HF, two products were obtained: 2-fluorobenzoic acid and 2-hydroxybenzoic acid, whereas with the anhydrous HF an essentially quantitative yield of 2-fluorobenzoic acid was formed.
Published Version
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