Lacmoid

Lacmoid is a chemical compound with the formula C₂₄H₁₆N₂O₆.^[1] It is synthesized by reacting sodium nitrite (NaNO₂) with resorcinol. It is a pH-sensitive dye which is turned red by acids and is used as a pH indicator under the name of lacmoid. It is usually a black-violet solid.^[2]

Lacmoid

Names
IUPAC name 2-Amino-3,6-bis(2,4-dihydroxyphenyl)-2-phenoxazone
Other names Resorcein
Identifiers
CAS Number	33869-21-5
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL4789704
ChemSpider	19040159
ECHA InfoCard	100.156.476
EC Number	628-183-8
PubChem CID	3940532
CompTox Dashboard (EPA)	DTXSID70657601
InChI InChI=1S/C24H16N2O6/c25-17-9-23-18(7-15(17)13-3-1-11(27)5-20(13)29)26-19-8-16(22(31)10-24(19)32-23)14-4-2-12(28)6-21(14)30/h1-10,27-30H,25H2 Key: ABNVFGQXCGFSFH-UHFFFAOYSA-N
SMILES O=C1C=C2OC3=CC(N)=C(C=C3N=C2C=C1C=4C=CC(O)=CC4O)C=5C=CC(O)=CC5O
Properties
Chemical formula	C24H16N2O6
Molar mass	428.400 g·mol−1
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references