I‐125 and I‐123 labelled iodobenzyl bromide, a useful alkylating agent for radiolabelling biologically important molecules

The radioiodination of 4‐trimethylsilylbenzyl bromide in acetic acid with no carrier added I‐125 and I‐123 iodide ion and N‐chlorosuccinimide (NCS) is a rapid, high yielding process which produces high specific activity 4‐[I‐125 or I‐123]iodobenzyl bromide. This radiolabelled alkylating agent has been efficiently reacted with N,N‐dimethylaniline and triphenylphosphine to generate radiolabelled quaternary ammonium and phosphonium salts, and should be useful for labelling other biologically important molecules which possess suitable nucleophilic functional groups.