The syntheses of no‐carrier‐added and carrier‐added ¹⁸F‐labelled haloperidol

Abstract

Abstract Fluorine‐18 labelled haloperidol ( 18 F‐HP) was synthesized by a fluorine‐fluorine exchange reaction on haloperidol, fluorine‐chlorine exchange on a chloro‐analog of haloperidol, and from 18 F‐labelled p‐fluorobenzonitrile prepared by two different exchange reactions. Nucleophilic fluorine was used in the form of tetra n‐butylammonium fluoride. The overall radiochemical yield, expressed at the end of syntheses was 5% for exchange in haloperidol and about 2%‐3% for exchange in chloroanalog in a 40 min synthesis (from the end of the irradiation). Specific activity up to 1 Ci/mmol for haloperidol and up to 5000 Ci/mmol for chloro‐analog as substrates were obtained. The syntheses using p‐substituted chloro‐and nitro‐benzonitriles as starting materials for the exchange reaction gave a product with an average specific activity of about 2000 Ci/mmol and in general an overall radiochemical yield of 5%–10%. Purification of [ 18 F]haloperidol was done by HPLC on a C‐18 column. The radiochemical purity as assessed by thin layer radiochromatography (TLRC) of the final product was at least 95%, with high chemical purity.