[2,2'-bi-1H-indole]-3,3'-diol

Leucoindigo is a dye and the reduced form of indigo carmine.

Crystals.

[2,2'-bi-1H-indole]-3,3'-diol slowly oxidizes in air to Indigotin.

[2,2'-bi-1H-indole]-3,3'-diol is an aminoalcohol. Amines are chemical bases. They neutralize acids to form salts plus water. These acid-base reactions are exothermic. The amount of heat that is evolved per mole of amine in a neutralization is largely independent of the strength of the amine as a base. Amines may be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. Flammable gaseous hydrogen is generated by amines in combination with strong reducing agents, such as hydrides.

Flash point data for [2,2'-bi-1H-indole]-3,3'-diol are not available. [2,2'-bi-1H-indole]-3,3'-diol is probably combustible.