Indoxyl
In organic chemistry, indoxyl is a nitrogenous substance with the chemical formula: CHNO.[1][2] Indoxyl is isomeric with oxindol and is obtained as an oily liquid.
Preparation
The Heumann indigo synthesis starts from anthranilic acid:
Anthanilic acid (1) reacts with chloroacetic acid to give phenylglycine-o-carboxylic acid. When treated in molten sodium carbonate, the 2-Indoxycarboxylic acid (3) decarboxylates to give indoxyl (4)
In nature indoxyl is derived from indican, which is a glycoside. The hydrolysis of indican yields β-D-glucose and indoxyl.
Indigo dye is a product of the mild oxidation of indoxyl.
Indoxyl can be found in urine, when associated with indoxyl sulfate, a cardiotoxin, which is detected by titration with Obermayer's reagent, which is a dilute solution of ferric chloride (FeCl) in hydrochloric acid (HCl).[3]