Acid Orange 7, also known as 2-naphthol orange 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- ...

. It is used for dyeing wool. It is produced by

azo coupling In organic chemistry, an azo coupling is an organic reaction between a diazonium compound () and another aromatic compound that produces an azo compound (). In this electrophilic aromatic substitution reaction, the aryldiazonium cation is the e ...

of β-naphthol and diazonium derivative of

sulfanilic acid Sulfanilic acid (4-aminobenzenesulfonic acid) is an organic compound with the formula H3NC6H4SO3. It is an off-white solid. It is a zwitterion, which explains its high melting point. It is a common building block in organic chemistry."Sulphanili ...

..www.chemicalland21.com
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References

Azo dyes Benzenesulfonates Organic sodium salts 2-Naphthols Acid dyes {{Organic-compound-stub