Rapid ‘on-column’ preparation of hydrogen [(11)C]cyanide from [(11)C]methyl iodide via [(11)C]formaldehyde

Hydrogen [(11)C]cyanide ([(11)C]HCN) is a versatile (11)C-labelling agent for the production of (11)C-labelled compounds used for positron emission tomography (PET). However, the traditional method for [(11)C]HCN production requires a dedicated infrastructure, limiting accessibility to [(11)C]HCN. Herein, we report a simple and efficient [(11)C]HCN production method that can be easily implemented in (11)C production facilities. The immediate production of [(11)C]HCN was achieved by passing gaseous [(11)C]methyl iodide ([(11)C]CH(3)I) through a small two-layered reaction column. The first layer contained an N-oxide and a sulfoxide for conversion of [(11)C]CH(3)I to [(11)C]formaldehyde ([(11)C]CH(2)O). The [(11)C]CH(2)O produced was subsequently converted to [(11)C]HCN in a second layer containing hydroxylamine-O-sulfonic acid. The yield of [(11)C]HCN produced by the current method was comparable to that of [(11)C]HCN produced by the traditional method. The use of oxymatrine and diphenyl sulfoxide for [(11)C]CH(2)O production prevented deterioration of the molar activity of [(11)C]HCN. Using this method, compounds labelled with [(11)C]HCN are now made easily accessible for PET synthesis applications using readily available labware, without the need for the ‘traditional’ dedicated cyanide synthesis infrastructure.