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Phenolphthalein

CAS Number
77-09-8
EC Number
201-004-7
Chemical Formula
C20H14O4
Molecular Weight
318.3 g/mol

Description

Phenolphthalein (CAS 77-09-8 ) is a pH-sensitive indicator compound that transitions from colorless to vivid pink-red under alkaline conditions. This makes it a standard tool in titration and analytical chemistry. In industrial settings, it functions as a colorimetric marker for detecting alkalinity in substrates, coatings, and treated surfaces. In the printing and packaging industry, indicator solutions are used to test paper substrates. These tests ensure compatibility with inks and adhesives during the manufacturing process. Textile and leather processors apply it to verify the pH of dye baths, wash liquors, and various finishing treatments. This verification is critical where residual alkali affects product quality. In concrete and construction material testing, it is the standard reagent for carbonation depth assessment on cut surfaces. Sprayed solutions reveal the boundary between carbonated and uncarbonated zones. Personal care formulators use it as a bench-level QC tool to confirm the alkalinity of cream, soap, and hair relaxer formulations. This ensures safety and consistency during development and production. The product is supplied as a white to pale yellow crystalline powder available in reagent-grade and ACS -grade specifications. These grades are suited to laboratory and analytical applications, as well as technical grade for industrial process use. Pre-prepared indicator solutions at standard concentrations are also commercially available. Contact us for supply of Phenolphthalein Request Quote

Other Names (Synonyms)

Prulet | Ex-Lax | Alpha-di(p-hydroxyphenyl)phthalide | 3,3-Bis(p-hydroxyphenyl)phthalide | 3,3-Bis(4-hydroxyphenyl)phthalide | 3,3-Bis(4-hydroxyphenyl)-2-benzofuran-1(3H)-one | 3,3-Bis(4-hydroxyphenyl)-1(3H)-isobenzofuranone | Phenolax

Key Technical Features

  • High Purity Grade standard
  • Consistent Batch Quality
  • Full Regulatory & REACH Support
  • Global Logistics Network enabled

Physical Properties

Melting Point262.5 °C
Boiling Point417.49°C (rough estimate)
Density1.277 g/cm³ @ Temp: 32 °C
Flash Point24 °C
Appearancewhite to light yellow crystal powde
ColorWhite to yellow-white
OdorOdorless
FormSolid
Water Solubility<0.1 g/100 mL
Vapor Pressure<0.00001 Pa ( 50 °C)
Refractive Index1.5400 (estimate)
pH7.8~10.0
Log P2.410

Safety & Handling

Danger
GHS08· Health HazardGHS07· Irritant

Hazard Statements

H317May cause an allergic skin reaction
H319Causes serious eye irritation
H341Suspected of causing genetic defects
H350May cause cancer
H351Suspected of causing cancer
H360May damage fertility or the unborn child
H361Suspected of damaging fertility or the unborn child
H372Causes damage to organs through prolonged or repeated exposure
H401Toxic to aquatic life
H412Harmful to aquatic life with long lasting effects

Precautionary Statements

P203Obtain, consult and follow expert instructions for use.
P260Do not breathe dust/fume/gas/mist/vapours/spray.
P261Avoid breathing dust/fume/gas/mist/vapours/spray.
P264Wash … thoroughly after handling.
P270Do not eat, drink or smoke when using this product.
P272Contaminated work clothing should not be allowed out of the workplace.
P273Avoid release to the environment.
P280Wear protective gloves/protective clothing/eye protection/face protection.
P318IF exposed or concerned, get medical advice.
P319Get medical advice/attention if you feel unwell.
P321Specific treatment (see … on this label).
P405Store locked up.
P501Dispose of contents/container in accordance with local regulations.
P265Wash … thoroughly after handling.
P352IF ON SKIN: Wash with plenty of water.
P317Get emergency medical help.
P317If eye irritation persists: Get medical advice/attention. Get emergency medical help.
P364Take off contaminated clothing and wash it before reuse.
P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

Trade & Regulatory

HS Code29322910
Storage Class6.1C - Combustible acute toxic Cat.3 toxic compounds or compounds which causing chronic effects
WGK (Germany)3