o-Cresolphthalein is a synthetic phthalein dye and pH indicator with the molecular formula C₂₂H₁₈O₄. and is also known as ortho-Cresolphthalein. It is an organic compound that is insoluble in water but soluble in ethanol and other suitable organic solvents. The compound shows a distinct color response as the pH changes from acidic to alkaline. It is generally colorless below about pH 8.2 and develops a pink to reddish-purple color near pH 9.8. This alkaline-range response makes o-Cresolphthalein particularly useful in titrations, laboratory testing, and analytical chemistry including colorimetric determination of calcium.
CAS No.: 596-27-0
Synonyms: 3,3′-dimethylphenolphthalein.
| Physical Properties | |
| Chemical formula | C22H18O4 |
| IUPAC Name | 3,3-Bis(4-hydroxy-3-methylphenyl)-2-benzofuran-1(3H)-one |
| Molecular weight | 346.382 g/mol |
| Appearance | Beige/Cream to yellow powder |
| Solubility | Insoluble in water and soluble in ethanol |
| Density | 82.7 g/mL |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Light Brown |
| Physical State | Solid |
| λmax | 565 – 569 nm |
| Melting Point | 223 °C |
| Ph | 8.2-9.8- Colourless to violet red |
| Odor | Odorless |
| Pictograms : | No Information Available |
| Hazard Statements : | No Information Available |
| Precautionary Statements: | No Information Available. |
o-Cresolphthalein is a synthetic phthalein dye and pH indicator with the molecular formula C₂₂H₁₈O₄. and is also known as ortho-Cresolphthalein. It is an organic compound that is insoluble in water but soluble in ethanol and other suitable organic solvents. The compound shows a distinct color response as the pH changes from acidic to alkaline. It is generally colorless below about pH 8.2 and develops a pink to reddish-purple color near pH 9.8. This alkaline-range response makes o-Cresolphthalein particularly useful in titrations, laboratory testing, and analytical chemistry including colorimetric determination of calcium.
CAS No.: 596-27-0
Synonyms: 3,3′-dimethylphenolphthalein.
| Physical Properties | |
| Chemical formula | C22H18O4 |
| IUPAC Name | 3,3-Bis(4-hydroxy-3-methylphenyl)-2-benzofuran-1(3H)-one |
| Molecular weight | 346.382 g/mol |
| Appearance | Beige/Cream to yellow powder |
| Solubility | Insoluble in water and soluble in ethanol |
| Density | 82.7 g/mL |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Light Brown |
| Physical State | Solid |
| λmax | 565 – 569 nm |
| Melting Point | 223 °C |
| Ph | 8.2-9.8- Colourless to violet red |
| Odor | Odorless |
| Pictograms : | No Information Available |
| Hazard Statements : | No Information Available |
| Precautionary Statements: | No Information Available. |
o-Cresolphthalein is a phthalein dye primarily used as a reversible pH indicator and a colorimetric reagent for detecting calcium. It is also used in alkaline titrations, calcium assays and related analytical research.
o-Cresolphthalein reported transition range is approximately pH 8.2–9.8 changing from colorless to red or purple as the solution becomes more alkaline.
