Ethyl Red, also known as Diethyl Red, is a synthetic azo dye and pH indicator with the chemical formula C₁₇H₁₉N₃O₂. It normally occurs as a dark purple to deep red powder and is slightly soluble in water while showing better solubility in alcohol based solvents such as ethanol or methanol. Its azo structure gives the compound its characteristic color and pH-responsive behavior. Ethyl Red changes from yellow under acidic conditions to red as the medium becomes more basic with a reported transition range around pH 4.0–6.0. This distinct color response makes Ethyl Red useful as a visual indicator in analytical chemistry.
CAS No.: 76058-33-8
Synonyms: Ethyl Red Indicator, 2-{(E)-[4-(diethylamino)phenyl]diazenyl}benzoic acid, 4-(Diethylamino)azobenzene-2′-carboxylic Acid, Diethyl Red.
| Physical Properties | |
| Chemical formula | C17H19N3O2 |
| IUPAC Name | 2-[[4-(diethylamino)phenyl]diazenyl]benzoic acid |
| Molecular weight | 297.35 g/mol |
| Solubility | Insoluble in water |
| Appearance | Orange to Brown to Dark purple powder to crystal |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Dark red to dark purple or maroon |
| Physical State | Solid |
| Melting Point | 133-137 °C |
| Ph | 1.0 |
| Pictograms : |  |
| Hazard Statements : | H315: Causes skin irritation H319: Causes serious eye irritation H335: May cause respiratory irritation |
| Precautionary Statements: | P261: Avoid breathing dust/fume/gas/mist/vapours/spray. P304+P340: IF INHALED: Remove victim to fresh air and Keep at rest in a position comfortable for breathing. P305+P351+P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing. P405: Store locked up. |
Ethyl Red, also known as Diethyl Red, is a synthetic azo dye and pH indicator with the chemical formula C₁₇H₁₉N₃O₂. It normally occurs as a dark purple to deep red powder and is slightly soluble in water while showing better solubility in alcohol based solvents such as ethanol or methanol. Its azo structure gives the compound its characteristic color and pH-responsive behavior. Ethyl Red changes from yellow under acidic conditions to red as the medium becomes more basic with a reported transition range around pH 4.0–6.0. This distinct color response makes Ethyl Red useful as a visual indicator in analytical chemistry.
CAS No.: 76058-33-8
Synonyms: Ethyl Red Indicator, 2-{(E)-[4-(diethylamino)phenyl]diazenyl}benzoic acid, 4-(Diethylamino)azobenzene-2′-carboxylic Acid, Diethyl Red.
| Physical Properties | |
| Chemical formula | C17H19N3O2 |
| IUPAC Name | 2-[[4-(diethylamino)phenyl]diazenyl]benzoic acid |
| Molecular weight | 297.35 g/mol |
| Solubility | Insoluble in water |
| Appearance | Orange to Brown to Dark purple powder to crystal |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Dark red to dark purple or maroon |
| Physical State | Solid |
| Melting Point | 133-137 °C |
| Ph | 1.0 |
| Pictograms : | |
| Hazard Statements : | H315: Causes skin irritation H319: Causes serious eye irritation H335: May cause respiratory irritation |
| Precautionary Statements: | P261: Avoid breathing dust/fume/gas/mist/vapours/spray. P304+P340: IF INHALED: Remove victim to fresh air and Keep at rest in a position comfortable for breathing. P305+P351+P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing. P405: Store locked up. |
Ethyl Red is an organic chemical compound primarily used as a pH indicator in analytical chemistry, particularly for titrations and laboratory research. It is also used in selected biochemical, spectrophotometric and industrial analytical procedures.
The Ethyl Red test indicates changes in acidity or alkalinity by producing a color change within a specific pH range of approximately 4.5-6.5.
Ethyl Red should be handled as a laboratory chemical reagent. Avoid ingestion, inhalation, and unnecessary skin or eye contact and follow the supplier’s Safety Data Sheet (SDS) for appropriate handling and protective measures.
