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105945

Sigma-Aldrich

Phenolphthalein

ACS reagent

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Synonym(s):
3,3-Bis(4-hydroxyphenyl)-1(3H)-isobenzofuranone
Empirical Formula (Hill Notation):
C20H14O4
CAS Number:
Molecular Weight:
318.32
Colour Index Number:
764
Beilstein:
284423
EC Number:
MDL number:
PubChem Substance ID:
NACRES:
NA.47

grade

ACS reagent

Quality Level

form

powder

technique(s)

titration: suitable

visual transition interval

8.0-10, colorless to red

mp

261-263 °C (lit.)

solubility

acetone: soluble

density

1.27 g/cm3 at 32 °C

λmax

374 nm (2nd)
552 nm

application(s)

diagnostic assay manufacturing
hematology
histology

storage temp.

room temp

SMILES string

Oc1ccc(cc1)C2(OC(=O)c3ccccc23)c4ccc(O)cc4

InChI

1S/C20H14O4/c21-15-9-5-13(6-10-15)20(14-7-11-16(22)12-8-14)18-4-2-1-3-17(18)19(23)24-20/h1-12,21-22H

InChI key

KJFMBFZCATUALV-UHFFFAOYSA-N

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1 of 4

This Item
3192361.07233114529
Phenolphthalein ACS reagent

Sigma-Aldrich

105945

Phenolphthalein

Phenolphthalein indicator ACS,Reag. Ph Eur

Supelco

1.07233

Phenolphthalein

Phenol Red ACS reagent

Sigma-Aldrich

114529

Phenol Red

form

powder

form

liquid

form

solid

form

powder

technique(s)

titration: suitable

technique(s)

-

technique(s)

-

technique(s)

titration: suitable

mp

261-263 °C (lit.)

mp

-35 °C

mp

263.7 °C

mp

-

solubility

acetone: soluble

solubility

-

solubility

-

solubility

-

density

1.27 g/cm3 at 32 °C

density

0.918 g/mL at 25 °C

density

1.296 g/cm3 at 20 °C

density

-

General description

Phenolphthalein is an indicator for acid-base titration reactions. It changes from colorless to violet-red between pH 8.3-9.8, it is red in extremely acidic solutions, and colorless in extremely alkaline solutions.

It is present as a nonionic, lipophilic lactone in aqueous neutral solutions. It exists as a hydrophilic dianion in alkaline solutions.

Application

Phenolphthalein has been commonly used as an indicator in the fields of biology and medicine. Its applications include:

  • the development of novel technique to monitor the vacuum freeze-drying process
  • the determination of the depth of carbonation in concrete
  • the utilization of liquid marbles to sense gaseous environmental components
  • the estimation of total acidity in vinegar
  • the assessment of sodium hydroxide penetration into potatoes following chemical peeling
  • as a model organic compound in the evaluation of the capture efficiency of various cyclodextrin constructs such as nanofiber-CD

Biochem/physiol Actions

Phenolphthalein is colorless in acidic solutions and turns pink in basic solutions.

Principle

Phenolphthalein undergoes structural modification when there is a change in pH or in the structural state of water. It is a nonionic, lipophilic colorless lactone in aqueous neutral solutions and a hydrophilic dianion in alkaline solutions.

Pictograms

Exclamation markHealth hazard

Signal Word

Danger

Hazard Classifications

Carc. 1B - Muta. 2 - Repr. 2 - Skin Irrit. 2

Storage Class Code

6.1C - Combustible, acute toxic Cat.3 / toxic compounds or compounds which causing chronic effects

WGK

WGK 3

Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

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Using phenolphthalein as a promising indicator to monitor the vacuum freeze-drying process
Liu, et al.
Materials Letters, 139 (2015)
Teaching New Tricks to an Old Indicator: pH-Switchable, Photoactive Microporous Polymer Networks from Phenolphthalein with Tunable CO2 Adsorption Power
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The experimental investigation of concrete carbonation depth
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Cement and Concrete Research, 36(9) (2006)
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