Select Page



  • Product Name: Phenolphthalein
  • Cas No.: 77-09-8
  • Purity: 98%-101.0%
  • MF: C20H14O4
  • Appearance: White powder
  • Package: Drum
  • Certificate: ISO
  • Application: It is is a chemical compound commonly used as a pH indicator. It changes color depending on the acidity or alkalinity of a solution.
  • Sample: Available

Send Email To Us


3 + 14 =

Product Detail

Phenolphthalein is an organic compound with the formula C20H14O4. It is a white to slightly yellow crystalline powder that is insoluble in water at room temperature, but soluble in organic solvents such as alcohols, ketones and esters. Phenolphthalein is also an indicator, mainly used in the acid-base titration process. Its solution is colorless, pink in weakly alkaline or neutral solutions, and a significant color shift occurs when pH is 8.2 or greater. The color transition range of chemical phenolphthalein is suitable for general acid-base titration reactions, such as neutralization of strong acids and bases. Because of its clear color change and high sensitivity, chemical phenolphthalein is widely used in chemical experiment, analysis and quality detection.

Product Parameter

Synonyms 3,3-Bis(4-hydroxyphenyl)-2-benzofuran-1(3H)-one;3,3-Bis(4-hydroxyphenyl)isobenzofuran-1(3H)-one
Chemical Formula C20H14O4 CAS Number 1977/9/8
Molar mass 318.328 g·mol−1
Appearance White powder
Odor Odorless
Density 1.277 g/cm3 (32 °C (90 °F))
Melting point 258–263 °C (496–505 °F; 531–536 K)
Boiling point 417.49°C (rough estimate)
Refractive index 1.5400 (estimate)
Flash point 24 °C
Solubility in water 400 mg/L
Solubility Insoluble in benzene and hexane; very soluble in ethanol and ether; slightly soluble in DMSO
log P 2.41


1. Acid-base titration indicator: Phenolphthalein is one of the most commonly used acid-base titration indicators. It is usually used to test the acidity and alkalinity of the solution, and is especially suitable for titration between the acidic solution and the strong alkali solution. Phenolphthalein appears colorless under weakly acidic and neutral conditions, and a distinct pink color under alkaline conditions, and this color transition is often used to detect titration endpoint.

2. Chemical analysis: Phenolphthalein can be used as an indicator for oxalic acid quantification and magnesium ion detection. In the quantification of oxalic acid, phenolphthalein as an indicator can indicate the concentration of oxalic acid. In magnesium ion detection, phenolphthalein can indicate the presence and concentration of magnesium ions.

3. Biochemical experiments: Phenolphthalein can be used as an indicator for some biochemical experiments to detect the presence or absence of substances, such as detecting the conduct of enzyme reactions and the formation of metabolites.

4. Dyes and pigments: Phenolphthalein can be used as a synthetic raw material for some organic dyes and pigments. It can be used as a dye to give fibers and other materials different colors.

Multiple uses of products

It use in Laboratories and Research Facilities,Educational Institutions,Pharmaceutical Industry,Food and Beverage Industry,Textile Industry,Medical and Clinical Laboratories,Water Treatment Industry,Pool and Spa Industry