Cresol Red is also known as o-Cresol Red or o-cresolsulfonephthalein. It is a triarylmethane dye belonging to the phthalein and sulfonephthalein groups with the chemical formula C21H17NaO5S. It is a reddish-brown crystalline dye known for its distinct pH-sensitive color response, with transitions from orange to yellow in strongly acidic conditions and from yellow to violet in mildly alkaline conditions. Its characteristic color behavior results from changes in the molecular form of the dye as the surrounding pH changes. Cresol Red is also used as a pH indicator and tracking dye in DNA, RNA and protein electrophoresis, and can be used with lead acetate for urease detection after PAGE.
CAS No.: 1733-12-6
Synonyms: o-Cresol sulfonephthalein.
| Physical Properties | |
| Chemical formula | C21H17NaO5S |
| IUPAC Name | 3,3-Bis(4-hydroxy-3-methylphenyl)-2,1λ6-benzoxathiole-1,1(3H)-dione |
| Molecular weight | 382.43Â g/mol |
| Solubility | Soluble in ethanol |
| Appearance | Green to maroon to black crystals or powder |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Dark red to brown |
| Physical State | Solid |
| Melting Point | 290 °C |
| Density | 0.998 g/mol3 |
| Odor | Odorless |
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| Pictograms : |  |
| Hazard Statements : | H315: Causes skin irritation H319: Causes serious eye irritation H335: May cause respiratory irritation |
| Precautionary Statements: | P264: Wash … thoroughly after handling. P280: Wear protective gloves/protective clothing/eye protection/face protection/hearing protection. P261: Avoid breathing dust/fume/gas/mist/vapours/spray. P271: Use only outdoors or in a well-ventilated area. P302+P352: IF ON SKIN: Wash with plenty of water. P332+P317: If skin irritation occurs: Get medical help. P362+P364: Take off contaminated clothing and wash it before reuse. P305+P351+P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. P304+P340: IF INHALED: Remove person to fresh air and keep comfortable for breathing. P319: Get medical help if you feel unwell. P403+P233: Store in a well-ventilated place. Keep container tightly closed. P405: Store locked up. |
Cresol Red is also known as o-Cresol Red or o-cresolsulfonephthalein. It is a triarylmethane dye belonging to the phthalein and sulfonephthalein groups with the chemical formula C21H17NaO5S. It is a reddish-brown crystalline dye known for its distinct pH-sensitive color response, with transitions from orange to yellow in strongly acidic conditions and from yellow to violet in mildly alkaline conditions. Its characteristic color behavior results from changes in the molecular form of the dye as the surrounding pH changes. Cresol Red is also used as a pH indicator and tracking dye in DNA, RNA and protein electrophoresis, and can be used with lead acetate for urease detection after PAGE.
CAS No.: 1733-12-6
Synonyms: o-Cresol sulfonephthalein.
| Physical Properties | |
| Chemical formula | C21H17NaO5S |
| IUPAC Name | 3,3-Bis(4-hydroxy-3-methylphenyl)-2,1λ6-benzoxathiole-1,1(3H)-dione |
| Molecular weight | 382.43Â g/mol |
| Solubility | Soluble in ethanol |
| Appearance | Green to maroon to black crystals or powder |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Dark red to brown |
| Physical State | Solid |
| Melting Point | 290 °C |
| Density | 0.998 g/mol3 |
| Odor | Odorless |
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| Pictograms : | |
| Hazard Statements : | H315: Causes skin irritation H319: Causes serious eye irritation H335: May cause respiratory irritation |
| Precautionary Statements: | P264: Wash … thoroughly after handling. P280: Wear protective gloves/protective clothing/eye protection/face protection/hearing protection. P261: Avoid breathing dust/fume/gas/mist/vapours/spray. P271: Use only outdoors or in a well-ventilated area. P302+P352: IF ON SKIN: Wash with plenty of water. P332+P317: If skin irritation occurs: Get medical help. P362+P364: Take off contaminated clothing and wash it before reuse. P305+P351+P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. P304+P340: IF INHALED: Remove person to fresh air and keep comfortable for breathing. P319: Get medical help if you feel unwell. P403+P233: Store in a well-ventilated place. Keep container tightly closed. P405: Store locked up. |
Cresol Red is mainly used as a pH indicator and tracking dye in electrophoresis. It can be used in DNA and RNA agarose gel electrophoresis and protein PAGE to track sample migration. It is also used with lead acetate after PAGE to detect urease activity.
Cresol Red and Phenol Red are different sulfonephthalein pH indicators. Both change color with pH but they have different chemical structures and different pH transition ranges which makes them suitable for different analytical applications.
Cresol Red is an acid-base pH indicator used to show changes in the acidity or alkalinity of a solution through a visible color change.
