Synthesis of [1-¹¹C]phenol

The synthesis of n.c.a. [1-¹¹C]phenol (3) which is a further important aromatic ¹¹C unit for potential PET radiotracers is decribed for the first time. [1-¹¹C]aniline (1) was diazotized and the [1-¹¹C]benzenediazonium bromide (2) formed was concentrated in situ to give 3. Before diazotization, 1 had to be purified twice by means of an adsorber resin and a cation exchange resin. Starting from the purified 1, 3 was obtained in a radiochemical purity of about 79 % within 10 min. Related to crude 1 from the one-pot process, thereproducible radiochemical yield of 3 was about 16 % (decay-corrected). ¹³C/¹¹C Co-labelling experiments were carried out in order to confirm the identity of 3 and the position of the label.