Cresol Red
Product name: Cresol red
Synonym(s): o-Cresolsulfonphthalein, Cresol red
CAS Number: 1733-12-6
Introduction
| Product Name | Cresol Red |
| Items | Specifications |
| pH color range | 6.5(yellow)-8.5(purple) |
| Maximum of Absorption(nm) λ1（pH6.5） λ2（pH8.5） | 432.0—436.0 571.0—574.0 |
| Mass Absorption Coefficient(L/cm·g) α1（λ1, pH6.5） α2（λ2, pH8.5） | 49.0—67.0 100.0—132.0 |
| Ethanol Dissolution Test | Pass test |
| Loss on drying | ≤3.0% |
| Residue on Ignition (as sulfate) | ≤0.2% |
Cresol Red (CAS 1733-12-6) is a commonly used acid-base indicator with significant applications in chemical analysis and laboratory testing.
- Chemical Name: Cresol Red
- Other Names: o-Cresolsulfonaphthalein, o-Cresol Red
- CAS Number: 1733-12-6
- Molecular Formula: C₂₁H₁₈O₅S
- Molecular Weight: 382.43
- EINECS Number: 217-064-2
- Structure: A sulfonphthalein compound, structurally derived from phenolphthalein
Physical and Chemical Properties
Cresol Red typically appears as a red to brownish powder, slightly soluble in water, but readily soluble in ethanol and dilute alkaline solutions. It exhibits a pH transition range of 7.2 (yellow) to 8.8 (purple-red), making it ideal as an indicator for weakly basic titrations. It is especially useful in non-aqueous titrations or when combined with other indicators for precise endpoint detection.
Due to its sensitive color response, it is also widely employed in environmental monitoring, water quality analysis, and biochemical experiments as a pH indicator.
Storage Conditions
- Store sealed in a cool, dry, and light-protected environment
- Avoid contact with strong oxidizing agents, strong acids, and strong bases
- For long-term storage, inert gas protection (e.g., nitrogen) is recommended to prevent degradation
