Home »Speciality Dyes and Biological Stains » Thymol Blue
Thymol blue, also known as thymolsulfonphthalein, is a type of sulfomephthalein dye. It is a crystalline powder that is brownish-green or reddish-brown in colour and is insoluble in water. However, it is soluble in alcohol and in solutions of dilute alkali.
PRODUCT SPECIFICATIONS | |
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Name of Product | Thymol Blue |
IUPAC Name | 4-[3-(4-hydroxy-2-methyl-5-propan-2-ylphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]-5-methyl-2-propan-2-ylphenol |
Synonyms | Thymolsulfonephthalein; Thymolsulfophthalein; Sodium thymol blue; Azul Timol; Timolo blu; Thymol Bleu; Thymolblau |
CAS No | 76-61-9 |
Molecular Formula | C27H30O5S |
Molecular Weight | 466.6 g/mol |
Pubchem CID | 65565 |
SR. No | Criteria | Limit/Specification |
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1 | Appearance (Form) | Solid powder |
2 | Appearance (Color) | Brownish-Green crystals |
3 | Melting point | 221-224 °C (dec.) (lit.) |
4 | Density | 0.979 g/cm3 |
5 | Solubility | Insoluble in water; Gives clear solution in 0.1% ethanol; |
6 | UV-vis (λmax) | 594 nm (1st) 376 nm (2nd) |
7 | Storage temp. | Room temp. |
Q. How does thymol blue indicator works?
An aqueous solution of thymol blue undergoes the color changes from red to yellow in an acid solution (pKa ≈ 1.6) and from yellow to blue in an alkaline solution (pKa ≈ 8.9), thus functioning as a pH indicator.
Q. What colour is thymol blue in neutral?