The name ether refers to any compound that has two alkyl groups linked through an oxygen atom. ‘Ether’ is also used as an everyday name for diethyl ether, Et2O. You might compare this use of the word ‘ether’ with the common use of the word ‘alcohol’ to mean ethanol. Diethyl ether is a highly flammable solvent that boils at only 35°C. It used to be used as an anaesthetic. Tetrahydrofuran (THF) is another commonly used solvent and is a cyclic ether. Brevetoxin B (overleaf) is a fascinating naturally occurring compound that was synthesized in the laboratory in 1995. It is packed with ether functional groups in ring sizes from 6 to 8.