Name | Alpha-Naphtholphthalein |
Synonyms | à-naphtholphthalein Alpha-Naphtholphthalein 1-NAPHTHOLPHTHALEIN, INDICATOR ALPHA-NAPHTHOLPHTHALEIN INDICATOR A-NAPHTHOLPHTHALEIN PRACTICAL GRADE 3,3-bis(4-hydroxy-1-naphthyl)phthalide alpha-Naphtholphthalein, indicator, pure 1(3H)-Isobenzofuranone, 3,3-bis(4-hydroxy-1-naphthalenyl)- |
CAS | 596-01-0 |
EINECS | 209-875-5 |
InChI | InChI=1/C28H18O4/c29-25-15-13-23(17-7-1-3-9-19(17)25)28(22-12-6-5-11-21(22)27(31)32-28)24-14-16-26(30)20-10-4-2-8-18(20)24/h1-16,29-30H |
InChIKey | HQHBAGKIEAOSNM-UHFFFAOYSA-N |
Molecular Formula | C28H18O4 |
Molar Mass | 418.44 |
Density | 1.1532 (rough estimate) |
Melting Point | 238-240°C(lit.) |
Boling Point | 496.21°C (rough estimate) |
Flash Point | 247°C |
Water Solubility | Soluble in ethanol. Insoluble in water. |
Solubility | Solubility Practically insoluble in water; soluble in ethanol |
Vapor Presure | 1.44E-20mmHg at 25°C |
Vapor Density | 14.44 (vs air) |
Appearance | Crystalline powder |
Color | Pink to beige or brown |
Odor | Characteristic odour |
Maximum wavelength(λmax) | ['648nm'] |
Merck | 14,6389 |
BRN | 97816 |
pKa | 8.0, 8.2, 8.5(at 25℃) |
PH | pH : 7.1~8.7 |
Storage Condition | Store below +30°C. |
Refractive Index | 1.6400 (estimate) |
MDL | MFCD00036202 |
Use | Used as an acid-base indicator, it is colorless to orange when the PH value is about 6.7, and it changes from orange to blue when the PH value is about 7.9. Commercial products containing impurities are mostly light red, which changes from light red to blue-green when the PH value is 7.3~8.7. |
Hazard Symbols | Xi - Irritant |
Risk Codes | 36/37/38 - Irritating to eyes, respiratory system and skin. |
Safety Description | S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36 - Wear suitable protective clothing. |
WGK Germany | 3 |
HS Code | 32041900 |
pH range of acid-base indicator discoloration | 7.1(brownish)-8.3(blue/green) |
Use | is used as an acid-base indicator, which is colorless to Orange at pH 6.7, and changes from orange to blue at pH 7.9. The impurities in the commercially available products are mostly light red, changing from light red to blue-green at pH 7.3~8.7. |
production method | 1. Prepared by heating phthalic anhydride with α-naphthol and zinc chloride to 100 °c to 110 °c. At the same time associated by-products, obtained by separation. 2.1-naphthol and phthalic anhydride were ground, according to the theoretical amount of mixing and concentrated sulfuric acid together with stirring into green viscous, maintain the temperature at 60 ℃ (not more than 65 ℃) under 19h, the condensation reaction was carried out: After cooling, the mixture was pulverized, soaked with ice water to form a loose yellow powder, washed with water, and spin-dried. Dissolve with 1% sodium hydroxide solution, heat to 60 ℃, filter while hot, cool the filtrate and neutralize to acid with 1: 1 hydrochloric acid solution below 10 ℃, the precipitated crystals are dried at low temperature to obtain a finished product. |