Acid red 88

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Acid red 88
Kekulé, skeletal formula of acid red 88
Ball-and-stick model of the component ions of acid red 88
IUPAC name
Sodium 4-(2-hydroxy-1-naphthalenylazo)-naphthalenesulfonate
Other names
Fast Red A

2-Naphthol Red
Solid Red A

Toyo roccelline
1658-56-6 (E)-diazen N
ChemSpider 23621588 N
EC Number 216-760-3
Jmol interactive 3D Image
MeSH Fast+red+S
PubChem 23722700
23669381 (Z)-diazen
23670762 (E)-diazen
RTECS number QK2420000
Molar mass 400.38 g·mol−1
Appearance Vivid, dark red, opaque, vitreous solid
Melting point 280 °C (536 °F; 553 K)
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

Acid red 88 (also named Solid Red A, 2-Naphthol Red, Toyo roccelline, Fast Red A and so on) is a red azo dye. Due to its intense colour it looks almost black when solid. Instead of crystallising, it vitrifies when cooled or salted out of the solution. It has a pungent smell similar to that of benzoic acid.


It can be obtained by azo coupling of naphthionic acid and 2-naphthol.

Naphthol red preparation.svg


This compound is used in the textile industry as a dye.[1] It can also be used for research in photocatalysis (as degradation object).[2]


External links[edit]