
Chlorophenol Red is a sulfonephthalein indicator dye with the chemical formula C₁₉H₁₂Cl₂O₅S. It is known for its clear pH-dependent color change, shifting from yellow to red violet as the solution becomes less acidic. This transition occurs in the near neutral pH range of approximately 5.2–6.8 which enables the dye to indicate changes in acidity. Chlorophenol Red also has applications in colorimetric enzyme assays, where it can act as an optical transducer for studying acetylcholinesterase inhibition. It has additionally been used for the selective determination of chlorine dioxide in drinking water and in assays for identifying transformed Zea mays colonies under phosphinothricin selection.

CAS No.: 4430-20-0
Synonyms: Dichlorophenolsulfonephthalein, Chlorphenol Red.
| Physical Properties | |
| Chemical formula | C19H12Cl2O5S |
| IUPAC Name | 3,3-Bis(3-chloro-4-hydroxyphenyl)-2, 1λ6-benzoxathiole-1,1(3H)-dione |
| Molecular weight | 423.26 g/mol |
| Solubility | Partially Soluble in water |
| Appearance | Green to red-brown to brown powder |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Red |
| Physical State | Solid |
| Melting Point | 261 °C |
| Ph | 4.8-6.7, yellow to violet |
| λmax | 572 nm |
| Pictograms : | ![]() |
| Hazard Statements : | H315: Causes skin irritation H319: Causes serious eye irritation H335: May cause respiratory irritation |
| Precautionary Statements: | P280: Wear protective gloves/eye protection P302+P352: IF ON SKIN: Wash with plenty of soap and water P305+P351+P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing |
Chlorophenol Red is a sulfonephthalein indicator dye with the chemical formula C₁₉H₁₂Cl₂O₅S. It is known for its clear pH-dependent color change, shifting from yellow to red violet as the solution becomes less acidic. This transition occurs in the near neutral pH range of approximately 5.2–6.8 which enables the dye to indicate changes in acidity. Chlorophenol Red also has applications in colorimetric enzyme assays, where it can act as an optical transducer for studying acetylcholinesterase inhibition. It has additionally been used for the selective determination of chlorine dioxide in drinking water and in assays for identifying transformed Zea mays colonies under phosphinothricin selection.

CAS No.: 4430-20-0
Synonyms: Dichlorophenolsulfonephthalein, Chlorphenol Red.
| Physical Properties | |
| Chemical formula | C19H12Cl2O5S |
| IUPAC Name | 3,3-Bis(3-chloro-4-hydroxyphenyl)-2, 1λ6-benzoxathiole-1,1(3H)-dione |
| Molecular weight | 423.26 g/mol |
| Solubility | Partially Soluble in water |
| Appearance | Green to red-brown to brown powder |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Red |
| Physical State | Solid |
| Melting Point | 261 °C |
| Ph | 4.8-6.7, yellow to violet |
| λmax | 572 nm |
| Pictograms : | ![]() |
| Hazard Statements : | H315: Causes skin irritation H319: Causes serious eye irritation H335: May cause respiratory irritation |
| Precautionary Statements: | P280: Wear protective gloves/eye protection P302+P352: IF ON SKIN: Wash with plenty of soap and water P305+P351+P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing |
Chlorophenol Red is mainly used as a pH indicator in chemical, biological, environmental and analytical applications. It is also used in enzyme assays and has been used for the selective determination of chlorine dioxide in drinking water. This makes it useful for both pH monitoring and colorimetric analytical testing.
The chemical formula of Chlorophenol Red is C₁₉H₁₂Cl₂O₅S. It is a sulfonephthalein dye and is also known as dichlorophenolsulphonephthalein and is primarily recognized for its pH-responsive color behavior.