Acetylenedicarboxylic_acid
Acetylenedicarboxylic acid
Chemical compound
Acetylenedicarboxylic acid or butynedioic acid is an organic compound (a dicarboxylic acid) with the formula H2C4O4 or HO−C(=O)−C≡C−C(=O)−OH. It is a crystalline solid that is soluble in diethyl ether.
The removal of two protons yields the acetylenedicarboxylate dianion C4O2−4, which consists only of carbon and oxygen, making it an oxocarbon anion. Partial ionization yields the monovalent hydrogen acetylenedicarboxylate anion HC4O−4.
The acid was first described in 1877 by Polish chemist Ernest Bandrowski.[2][3][4] It can be obtained by treating α,β-dibromosuccinic acid with potassium hydroxide KOH in methanol or ethanol. The reaction yields potassium bromide and potassium acetylenedicarboxylate. The salts are separated and the latter is treated with sulfuric acid.[2]
Acetylenedicarboxylic acid is used in the synthesis of dimethyl acetylenedicarboxylate, an important laboratory reagent. The acid is commonly traded as a laboratory chemical. It can also be reacted with sulfur tetrafluoride to produce hexafluoro-2-butyne, a powerful dienophile for use in Diels-Alder reactions.
Fatty alcohol esters of acetylenedicarboxylic acid can be used for the preparation of phase change materials (PCM).[5]