Thiotimoline is a fictitious chemical compound conceived by science fiction author Isaac Asimov and first described in a spoof scientific paper titled “The Endochronic Properties of Resublimated Thiotimoline” in 1948. Asimov went on to write three additional short stories, each describing different properties or uses of thiotimoline.

In Asimov’s writing, thiotimoline is notable for the fact that when it is mixed with water, the chemical actually begins to dissolve before it contacts the water. This is explained by the fact that in the thiotimoline molecule, there is at least one carbon atom such that, while two of the carbon’s fourchemical bonds lie in normal space and time, one of the bonds projects into the future and another into the past. Thiotimoline is derived from the bark of the (fictitious) shrub Rosacea karlsbadensis rufo, and the thiotimoline molecule includes at least fourteen hydroxy groups, two aminogroups, and one sulfonic acid group, and possibly one nitro compound group as well. The nature of the hydrocarbon nucleus is unknown, although it seems in part to be an aromatic hydrocarbon.