Thymol Blue Pure

Thymol Blue
Other Names: Thymolsulfonephthalein, α-hydroxy-α,α-bis(5-hydroxycarvacryl)-o-toluenesulfonic acid γ-sultone

CAS Number: 76-61-9
Sum Formula: C₂₇H₃₀O₅S
Molar Mass: 466.59 g/mol
Appearance: Reddish-brown to purple crystalline powder

Thymol Blue is a sulfonephthalein dye used as a pH indicator. It exhibits two distinct color transitions and is valued in both aqueous and non-aqueous acid–base titrations. Its structure is based on thymol groups and a sulfonated aromatic system.

Chemical and Physical Properties
Density: Approx. 1.3 g/cm³ (estimated)
Melting Point: Decomposes above 220°C
Boiling Point: Not applicable (decomposes)
Solubility in Water: Slightly soluble
Solubility in Other Solvents: Soluble in alcohol, ether, and alkaline solutions
Odor: Odorless

pH Range and Color Transitions:

• pH 1.2 – 2.8: Red → Yellow

• pH 8.0 – 9.6: Yellow → Blue

Applications
pH Indicator: Used in laboratory titrations and buffer preparations across two pH transition ranges.
Analytical Chemistry: Helps visualize acidity/basicity shifts in chemical processes.
Colorimetric Studies: Utilized in educational and research settings for pH-dependent color demonstration.
Solvent Systems: Applied in non-aqueous titrations due to its dual transition range.

Safety

Signal Word: Warning

Handling and Storage
Storage Conditions: Store in a tightly sealed container in a dry, cool, and well-ventilated area. Protect from heat and light.
Handling Precautions: Avoid inhalation and contact with eyes or skin. Handle with appropriate protective measures and under standard laboratory safety protocols.