Meconic acid

• 3-hydroxy- 4-oxo- 4H-pyran -2 ,6 -dicarboxylic acid (IUPAC)
• Acidum Meconicum
• Poppy Acid

Colorless needles, flakes or scales

120 ° C ( decomposition)

• PKS1 1.83
• PKS2 2.11

• Little in water ( 8.4 g · l-1 at 25 ° C ) and methanol
• Soluble in ethanol and benzene

Template: Infobox chemical / molecular formula search available

Meconic, also called Acidum Meconicum, is a chemical compound from the group of pyrones, which in some poppy family ( Papaveraceae ), as in opium poppy (Papaver somniferum ) and medicinal poppy ( Papaver bracteatum ) is included. The connection is with 4-6% of the ingredients of opium ( Mekon = Greek poppy capsule ) and can be used for the detection of opium.

Meconic was erroneously described as a narcotic effect, although there is no or only a slight physiological effect and shows not used medicinally. The pyrone forms with alkaloids and metals salts Mekonate. The French chemist Armand Seguin had progressed so far with his experiments until 1804 to be able to generate meconic, but without knowing whether this was a specific acid or a mixture contaminated with herbal ingredients. Meconic finally was first isolated in 1805 by Friedrich Sertürner.

Properties

Meconic one of the dicarboxylic acids; it is a strong acid with the PKS1 - value 1.83 and pKa2 of 2.11. Its structure contains two carboxyl groups (-COOH ), a hydroxy group (-OH), which are located at a pyrone ring. The substance is colorless and only slightly soluble in water and methanol, preferably in ethanol and benzene. Crystallization from aqueous solution leads to a trihydrate, which forms orthorhombic platelets. When heated, meconic decomposed gradually, forming by simple decarboxylation Komen acid at temperatures from 200 ° C. Meconic acid shows - as some phenols and phenolic acids - a red color in the reaction with iron ( III) chloride and the titrimetric determination of Fe (III ) ions are used.