Lithol Rubine BK

Lithol Rubine BK

Names
IUPAC name Calcium (4Z)-4-[(4-methyl-2-sulfonatophenyl)hydrazono]-3-oxo-2-naphthalenecarboxylate
Other names Pigment Rubine, Carmine 6B, Brilliant Carmine 6B, Permanent Rubin L6B, Litholrubine, Latolrubine, C.I. Pigment Red 57, C.I. Pigment Red 57:1, D&C Red No. 7, or C.I. 15850:1; E180
Identifiers
CAS Number	5281-04-9
ChemSpider	17215383
Jmol interactive 3D	Image
PubChem	9571018
UNII	ECW0LZ41X8
InChI InChI=1S/C18H14N2O6S.Ca/c1-10-6-7-14(15(8-10)27(24,25)26)19-20-16-12-5-3-2-4-11(12)9-13(17(16)21)18(22)23;/h2-9,21H,1H3,(H,22,23)(H,24,25,26);/q;+2/p-2/b20-19+; Key: PZTQVMXMKVTIRC-RZLHGTIFSA-L InChI=1/C18H14N2O6S.Ca/c1-10-6-7-14(15(8-10)27(24,25)26)19-20-16-12-5-3-2-4-11(12)9-13(17(16)21)18(22)23;/h2-9,21H,1H3,(H,22,23)(H,24,25,26);/q;+2/p-2/b20-19+; Key: PZTQVMXMKVTIRC-LGRYAOMWBK
SMILES [Ca+2].[O-]S(=O)(=O)c3cc(C)ccc3/N=N/c1c2ccccc2cc(C([O-])=O)c1O
Properties
Chemical formula	C18H12CaN2O6S
Molar mass	424.44 g/mol
Appearance	Red powder
Solubility in water	slightly soluble in hot water, insoluble in cold water and ethanol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Lithol Rubine BK is a reddish synthetic azo dye. It has the appearance of a red powder and magenta when printed. It is slightly soluble in hot water, insoluble in cold water, and insoluble in ethanol. When dissolved in dimethylformamide, its absorption maximum lies at about 442 nm. It is usually supplied as a calcium salt.^[1]

It is used to dye plastics, paints, printing inks, and for textile printing. It is normally used as a standard magenta in the three and four color printing processes.

When used as a food dye, it has E number E180. It is used to color cheese rind as well as a component in some lip balms. It is banned in some countries.

References

1. K. Hunger. W. Herbst "Pigments, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2012. doi:10.1002/14356007.a20_371