Acetylenedicarboxylic acid is employed in the preparation of dimethyl acetylenedicarboxylate and potassium hydrogenacetylenedicarboxylate. It is also used as a laboratory reagent. Further, it is used as a precursor in organic synthesis and also serves as a pharmaceutical intermediate.
The acid is soluble in Et2O and crystallises from Et2O/pet ether (m 183-183.5o), or H2O as the dihydrate which dehydrates in a desiccator over conc H2SO4 in a vacuum. The dipicrate crystallises from aqueous ether. For the mono K salt see entry in “Metal-organic Compounds”, Chapter 5. [Abbott et al. Org Synth Coll Vol II 10 1943, Huntress et al. Org Synth Coll Vol IV 329 1963, Beilstein 2 H 801, 2 I 317, 2 II 670, 2 III 1991, 2 IV 2290.]
