Propynyllithium is an organolithium compound with the chemical formula LiC2CH3.

To preclude its degradation by oxygen and water, propynyllithium and its solutions are handled under inert gas (argon or nitrogen).

[1] Although commonly depicted as a monomer, propynyllithium adopts a more complicated cluster structure as seen for many other organolithium compounds.

Various preparations of propynyllithium are known, but the most expeditious route starts with 1-bromopropene:[2][3] It can be prepared by passing propyne gas through a solution of n-butyllithium[4] or by direct metallization of propyne with lithium in liquid ammonia or other solvent.

These reactions are used in the synthesis of complex natural and synthetic substances such as the drug mifepristone.