The halogenated alkanes (alkyl halides, also known as haloalkanes) in general, and in particular the fluorinated compounds were promising because they were volatile but not flammable. Suckling had worked on such compounds extensively during World War II, when they were used in the production of high-octane aviation fuel, and in the purification of uranium-235. He proceeded to synthesise a variety of fluorinated hydrocarbons before evaluating them for anaesthetic properties. He liaised closely with clinicians, initially in setting target physicochemical properties for ideal agents and then later in evaluating the developed compounds.