Tropaeolin is the retained name for some azo dyes from the industrially applied group of acid dyes used as pH indicators. The name is derived from the botanical name Tropaeolum for nasturtiums.[1]

Examples for Tropaeolin dyes

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Name C.I.-Name Structure CAS number Indicator properties Other uses
Tropaeolin O

(Resorcingelb)

Acid Orange 6

Food Yellow 8

  547-57-9 pH 11.1–12.7 yellow/brown
Tropaeolin OO

(Orange IV)

Acid Orange 5   554-73-4 pH 1.2–3.2 violet-red/yellow Dye for wool
Tropaeolin OOO1

(Orange I)

Acid Orange 20   523-44-4 pH 7.6–8.9 yellow/pink
Tropaeolin OOO2

(Orange II)

Acid Orange 7   633-96-5 pH 7.4–8.6 amber/orange Dye for wool and silk
Tropaeolin D

(Methylorange)

Acid Orange 52   547-58-0 pH 3.1–4.4 red Textile dye (USA)
Tropaeolin G

(Metanilgelb)

Acid Yellow 36   587-98-4 pH 1.2–2.3 yellow
Tropaeolin RNP

(Resorcinbraun)

Acid Orange 24   1320-07-6 Coloring cosmetics

References

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  1. ^ Jürgen Falbe, Manfred Regitz, ed. (1999). Tropäolin (in German). Vol. 6: T-Z. Stuttgart, New York: Georg Thieme Verlag. p. 4683. ISBN 3-13-735110-3. {{cite book}}: |periodical= ignored (help)