Which less flammable solvent did Chain suggest as an alternative to ether?

Ernst Chain suggested amyl acetate as a less flammable alternative to ether for extracting penicillin. The Oxford team needed an organic solvent that could remove penicillin from the acidified culture liquid without creating the same fire hazard as ether.

Ether was initially used because it dissolved penicillin, but it was highly inflammable and toxic. In a wartime laboratory handling large volumes, that posed a serious practical problem. Chain proposed trying amyl acetate, which was much less flammable, and the experiment showed that it also extracted penicillin effectively.

The substitution was part of a larger purification process. After acidification with phosphoric acid and cooling, penicillin moved into the solvent phase. The Oxford group later developed a reverse-extraction step to move it back into water under changed alkaline conditions, helping concentrate and purify the antibiotic.

Amyl acetate did not make the procedure simple or risk-free, but it made scale-up more practical. The Oxford work ultimately transformed Fleming’s observation into a process capable of producing material for animal experiments and early human treatment.