Basic Red 18 is a cationic azo dye used for coloring textiles. The chromophore is the cation, which contains many functional groups, but most prominently the quaternary ammonium center.

Basic Red 18

Names
Other names Aizen Cathilon Red GTLH, Astrazon Red GTL
Identifiers
CAS Number	25198-22-5 Y
3D model (JSmol)	Interactive image
ECHA InfoCard	100.034.482
EC Number	237-946-0
PubChem CID	26457
UNII	H5KZY0428H Y
CompTox Dashboard (EPA)	DTXSID60864468
InChI InChI=1S/C19H25ClN5O2/c1-5-23(12-13-25(2,3)4)16-8-6-15(7-9-16)21-22-19-11-10-17(24(26)27)14-18(19)20/h6-11,14H,5,12-13H2,1-4H3/q+1 Key: TZXATTMVGZDPHM-UHFFFAOYSA-N
SMILES CCN(CC[N+](C)(C)C)C1=CC=C(C=C1)N=NC2=C(C=C(C=C2)[N+](=O)[O-])Cl
Properties
Chemical formula	C19H25Cl2N5O2
Molar mass	426.34 g·mol−1
Appearance	dark red solid
Melting point	45.5–46.5 °C (113.9–115.7 °F; 318.6–319.6 K)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H318, H412
Precautionary statements	P264, P270, P273, P280, P301+P312, P305+P351+P338, P310, P330, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

It is produced by azo coupling of 2-chloro-4-nitrophenyldiazonium cation with the quaternary ammonium salt derived from N-ethyl-N-(2-chloroethyl)aniline and trimethylamine.^[1]

Like many dyes, methods for the removal of Basic Red 18 from waste streams has received much attention.^[2]