α-Naphtholphthalein is an organic phthalein dye with the chemical formula C₂₈H₁₈O₄. It is also known as 1-Naphtholphthalein and belongs to a class of compounds widely used as pH indicators. Its chemical structure contains two naphthalene rings linked through a phthalic acid derived group. The compound generally occurs as a crystalline solid with low solubility in water but dissolves in organic solvents such as alcohol and ether. Its pH-responsive optical behavior allows it to produce visible changes under different chemical conditions.
CAS No.: 596-01-0
Synonyms: 1-Naphtholphthalein, alpha-naphtholphthalein, naphtholphthalein blue.
| Physical Properties | |
| Chemical formula | C28H18O4 |
| IUPAC Name | 3,3-Bis(4-hydroxynaphthalen-1-yl)-2-benzofuran-1(3H)-one |
| Molecular weight | 418 g/mol |
| Solubility | Insoluble in water and soluble in ethanol |
| Flash Point | 247 °C |
| Appearance | Light Pink to Beige to Red-Brown Powder |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Black |
| Physical State | Solid |
| Melting Point | 238–240 °C |
| Vapor Presssure | 1.44E-20mmHg at 25°C |
| Ph | 7.1- 8.7 |
| λmax | 648 nm |
| Odor | Odorless |
| 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. P305 + P351 + P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. |
α-Naphtholphthalein is an organic phthalein dye with the chemical formula C₂₈H₁₈O₄. It is also known as 1-Naphtholphthalein and belongs to a class of compounds widely used as pH indicators. Its chemical structure contains two naphthalene rings linked through a phthalic acid derived group. The compound generally occurs as a crystalline solid with low solubility in water but dissolves in organic solvents such as alcohol and ether. Its pH-responsive optical behavior allows it to produce visible changes under different chemical conditions.
CAS No.: 596-01-0
Synonyms: 1-Naphtholphthalein, alpha-naphtholphthalein, naphtholphthalein blue.
| Physical Properties | |
| Chemical formula | C28H18O4 |
| IUPAC Name | 3,3-Bis(4-hydroxynaphthalen-1-yl)-2-benzofuran-1(3H)-one |
| Molecular weight | 418 g/mol |
| Solubility | Insoluble in water and soluble in ethanol |
| Flash Point | 247 °C |
| Appearance | Light Pink to Beige to Red-Brown Powder |
| Storage | Store at room temperature |
| Chemical Properties | |
| Color | Black |
| Physical State | Solid |
| Melting Point | 238–240 °C |
| Vapor Presssure | 1.44E-20mmHg at 25°C |
| Ph | 7.1- 8.7 |
| λmax | 648 nm |
| Odor | Odorless |
| 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. P305 + P351 + P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. |
a-Naphtholphthalein is mainly used as a pH indicator in analytical chemistry and acid-base titrations. It is also used in pH-responsive textiles such as medical gauze and compression bandages for monitoring changes in wound pH.
a-Naphtholphthalein can be used as an acid-base indicator in titration methods when the endpoint falls within its transition range.
