Acid Red 13 is an
azo dye
Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C-N=N ...
.
[.] It is produced as a sodium salt. Solid samples appear dark red.
References
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Azo dyes
Organic sodium salts
Naphthalenesulfonates
2-Naphthols