Propiolic acid is the organic compound with the formula HC2CO2H. It is the simplest acetylenic carboxylic acid. It is a colourless liquid that crystallises to give silky crystals. Near its boiling point, it decomposes.
It is soluble in water and possesses an odor like that of acetic acid.[4][5]
It is prepared commercially by oxidizing propargyl alcohol at a lead electrode.[6] It can also be prepared by decarboxylation of acetylenedicarboxylic acid.
Exposure to sunlight converts it into trimesic acid (benzene-1,3,5-tricarboxylic acid).[5] It undergoes bromination to give dibromoacrylic acid. With hydrogen chloride it forms chloroacrylic acid. Its ethyl ester condenses with hydrazine to form pyrazolone.[5]
It forms a characteristic explosive solid upon treatment to its aqueous solution with ammoniacal silver nitrate.[5] An amorphous explosive precipitate forms with ammoniacal cuprous chloride.
Propiolates are esters or salts of propiolic acid. Common examples include methyl propiolate and ethyl propiolate.