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Thermochromic dyes have been used as chemical indicators and for recording paper
Thermochromic dyes have been used as chemical indicators and for recording paper
crystal violet lactone
spiropyrans
fulgides
Strictly, these dyes are not thermochromic but change colur in response to a change in pH
phenolphthalein and thymolphtalein are colourless in acidic to neutral pH but become pink and blue in akaline environments.
redox indicators
Electron acceptors - or more strictly proton donors
bisphenol A,
octyl p-hydrobenzoate
methyl p-hydroxybenzoate
1,2,3-triazoles
4-hydroxycoumarin
All weak acids. Weak acids give reversible colour change, strong acids irreversible chnage
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