Amidol

Amidol[1]
IUPAC name 2,4-Diaminophenol
Identifiers
CAS number	95-86-3,  [137-09-7] (dihydrochloride)
PubChem	7266
ChemSpider	6996 Y
UNII	NNB4I01PA7 Y
Jmol-3D images	Image 1 Image 2
SMILES NC1=CC(N)=C(O)C=C1 Oc1ccc(N)cc1N
InChI InChI=1S/C6H8N2O/c7-4-1-2-6(9)5(8)3-4/h1-3,9H,7-8H2 Y Key: XIWMTQIUUWJNRP-UHFFFAOYSA-N Y InChI=1/C6H8N2O/c7-4-1-2-6(9)5(8)3-4/h1-3,9H,7-8H2 Key: XIWMTQIUUWJNRP-UHFFFAOYAD
Properties
Molecular formula	C6H8N2O
Molar mass	124.14 g/mol
Appearance	Colorless solid
Melting point	78-80 °C
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Amidol is a colorless crystalline compound with the molecular structure C₆H₃(NH₂)₂OH. It is a dihydrogen chloride salt and is used as a photographic developer. It was introduced as a developing agent for photographic papers in 1892. It is unusual amongst developing agents as it works most effectively in slightly acid conditions rather than the strongly alkaline conditions required for most other developers. As amidol ages it changes color to a dark red-brown. Developing dishes and equipment used to prepare amidol solutions are also frequently stained brown, a stain that is very persistent.

Prints developed in amidol are typically a very warm brown-black colour, but overdevelopment can quickly lead to chemical fogging.

References

1. ^ Merck Index, 11th Edition, 2961.