What is 2-Butyne-1,4-diol?

2-Butyne-1,4-diol is HOCH2–C≡C–CH2OH, an unsaturated diol with the formula C4H6O2 and a molecular weight of 86.09 g/mol. The triple bond makes the carbon skeleton rigid and linear between the two hydroxymethyl ends, which is the key to its use as a rigid linker and as a hydrogen-bonding monomer. It melts at 53–58 °C, boils at 238 °C, and has a very low vapour pressure (below 0.1 mmHg at 55 °C).

The reference listing describes it as a 99% crystalline material with a closed-cup flash point of 152 °C. It ships under UN 2716, the entry for 1,4-butynediol.

Uses of 2-Butyne-1,4-diol

Industrially, the compound is the gateway from acetylene chemistry to the C4 diols. Semi-hydrogenation over a poisoned catalyst gives cis-2-butene-1,4-diol, and full hydrogenation gives 1,4-butanediol, which is used in polyurethane, polyester and tetrahydrofuran production. In electroplating, ppm-level concentrations of butynediol are used to refine nickel deposits, and in metal cleaning it reduces acid attack on steel.

In research, the symmetrical alkyne is a reliable reagent for cycloaddition and cyclotrimerisation chemistry, delivering fused and multi-substituted aromatic frameworks. Its protected derivatives are frequent building blocks in total synthesis.

Buying and Handling Considerations

Because the material is toxic by all routes and corrosive, plan for closed handling, local exhaust ventilation and personal protective equipment. Do not confuse it with 2-butyne (a volatile hydrocarbon) or 2-butyn-1-ol (a mono-alcohol); the CAS number 110-65-6 identifies this diol. Store in a tightly closed container in a cool, dry place, separate from strong oxidisers, strong acids and bases, and certain metal salts (acetylenic compounds can form metal acetylides with copper, silver and mercury salts). Report any signs of discolouration to your quality team before use.