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105945

Sigma-Aldrich

Phenolphthalein

ACS reagent

Synonym(s):

3,3-Bis(4-hydroxyphenyl)-1(3H)-isobenzofuranone

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About This Item

Empirical Formula (Hill Notation):
C20H14O4
CAS Number:
77-09-8
Molecular Weight:
318.32
Colour Index Number:
764
Beilstein:
284423
EC Number:
201-004-7
MDL number:
MFCD00005913
UNSPSC Code:
12171500
PubChem Substance ID:
24846716
NACRES:
NA.47

grade

ACS reagent

Quality Level

200

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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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

Health hazardExclamation mark
GHS08,GHS07

Signal Word

Danger

Hazard Statements

H315,H341,H350,H361f

Hazard Classifications

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

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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Conn?s Biological Stains: A Handbook of Dyes, Stains and Fluorochromes for Use in Biology and Medicine (10th ed.)
RW Horobin, JW Kiernan (Eds.)
Conn?s Biological Stains (2002)
Using phenolphthalein as a promising indicator to monitor the vacuum freeze-drying process
Liu, et al.
Materials Letters, 139 (2015)
The experimental investigation of concrete carbonation depth
Cheng-Feng Chang, Jing-Wen Chen
Cement and Concrete Research, 36(9) (2006)
Teaching New Tricks to an Old Indicator: pH-Switchable, Photoactive Microporous Polymer Networks from Phenolphthalein with Tunable CO2 Adsorption Power
Kiskan, et al.
Macromolecules (2012)
Min Guk Kim et al.
Journal of personalized medicine, 10(4) (2020-10-15)
Unbalanced dietary habits and the consumption of high protein and instant foods cause an increase in constipation. Here, we evaluated the effects of galacto-oligosaccharide (GOS) on a rat model of loperamide-induced constipation by measuring various biological markers and cecal microbiota.
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