Efficient and reproducible synthesis of [1-11C]acetyl chloride using the loop method

[1-11C]Acetyl chloride ([11C]AcCl), an important [11C]acylating agent, was synthesized by reacting [11C]CO2 with methylmagnesium bromide coated on the inner surface of a polyethylene loop (loop method). By optimizing the reaction conditions and synthesis parameters, [1-11C]phenylacetate and [1-11C]benzylacetate were produced from [11C]AcCl in high radiochemical yield and specific activity.