A summary of the most common chemical descriptors (InChI Key and SMILES codes) for Phenolphthalein are summarized together with 3D and 2D structures and relevant physico-chemical properties.

What is the Phenolphthalein?

The molecule Phenolphthalein presents a molecular formula of C20H14O4 and its IUPAC name is 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one.

Phenolphthalein is a molecule with a long and complicated history. It was first synthesized in 1834 by a German chemist named Friedlieb Ferdinand Runge, who is best known for being the first to isolate caffeine. Runge was working for the German pharmaceutical company Merck at the time, and his boss tasked him with finding a way to make a white powder that would turn red in the presence of acid. Runge succeeded in his mission, and the resulting molecule was given the name “phenolphthalein” by another Merck chemist, Wilhelm Rudolph Fittig..

Phenolphthalein quickly became a popular chemical indicator, due to its ability to change color in the presence of acid. It was used in titration experiments and in school science classrooms around the world. However, its popularity began to decline in the early 20th century, after it was discovered that phenolphthalein could be used as a laxative. This led to its inclusion in a number of over-the-counter and prescription medications, and its use as a laxative became so widespread that it began to be known as “the drug that made the world constipated”..

In the 1970s, phenolphthalein was linked to cancer in rats, and it was subsequently banned from use in many countries. It is still used in some countries, however, and it is still available for purchase in the United States. Phenolphthalein has a long and complicated history, but it remains a molecule of interest to chemists and scientists today..

3D structure

Cartesian coordinates

Geometry of Phenolphthalein in x, y and z coordinates (Å units) to copy/paste elsewhere. Generated with Open Babel software.

2D drawing


Phenolphthalein KJFMBFZCATUALV-UHFFFAOYSA-N chemical compound 2D structure molecule svg


Molecule descriptors

IUPAC name3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one
InChI codeInChI=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

Other names (synonyms)

IUPAC nomenclature provides a standardized method for naming chemical compounds. Although this system is widely used in chemistry, many chemical compounds have also other names commonly used in different contexts. These synonyms can come from a variety of sources and are used for a variety of purposes.

One common source of synonyms for chemical compounds is the common or trivial names, assigned on the basis of appearance, properties, or origin of the molecule.

Another source of synonyms are historical or obsolete names employed in the past, however replaced nowadays by more modern or standardized names.

In addition to common and historical names, chemical compounds may also have synonyms that are specific to a particular field or industry.

  • .alpha., .alpha.-Di(p-hydroxyphenyl)phthalide
  • 1(3H)-Isobenzofuranone, 3,3-bis(4-hydroxyphenyl)-
  • 1(3H)-Isobenzofuranone,3-bis(4-hydroxyphenyl)-
  • 3, 3-Bis(p-hydroxyphenyl)-1(3H)-isobenzofuranone
  • 3,3-Bis(4-hydroxyphenyl)-1(3H)-isobenzofuranone
  • 3,3-Bis(4-hydroxyphenyl)-2-benzofuran-1(3H)-one
  • 3,3-Bis(4-hydroxyphenyl)-2-benzofuran-1(3H)-one #
  • 3,3-Bis(4-hydroxyphenyl)isobenzofuran-1(3H)-one
  • 3,3-Bis(4-hydroxyphenyl)phthalide
  • 3,3-Bis(p-hydroxyphenyl)phthalide
  • 3,3-Bis-(4-hydroxy-phenyl)-3H-isobenzofuran-1-one
  • 3,3-bis (4-hydroxyphenyl)-2-benzofuran-1-on
  • 3,3-bis(4-hydroxyphenyl)-1,3-dihydro-2-benzofuran-1-one
  • 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-on
  • 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one
  • 3,3-bis(4-hydroxyphenyl)-3-hydroisobenzofuran-1-one
  • 3,3-bis(4-hydroxyphenyl)isobenzofuran-1-one
  • 6QK969R2IF
  • 77-09-8
  • AB00052070_15
  • AC-14431
  • AI3-09081
  • AMY37148
  • Agoral
  • Alophen
  • BBL002030
  • BCBcMAP01_000174
  • BDBM50077844
  • BIDD:ER0202
  • BP-30100
  • BRN 0284423
  • BSPBio_002518
  • CCG-39112
  • CCRIS 6266
  • CS-8152
  • Colax
  • Correctol
  • D05456
  • DB04824
  • DSSTox_CID_1125
  • DSSTox_GSID_21125
  • DSSTox_RID_75956
  • Dihydroxyphthalophenone
  • DivK1c_000929
  • Doxidan
  • EC 201-004-7
  • EN300-92962
  • EU-0082600
  • Espotabs
  • Euchessina
  • Evac-Q-Kit
  • Evac-Q-Kwik
  • Evac-U-Gen
  • F0921-4309
  • FGT
  • FT-0659094
  • Feen-A-Mint Gum
  • Feen-A-Mint Laxative Mints
  • FemiLax
  • Fenolftalein
  • Fenolftaleina
  • H12020
  • HMS1920H04
  • HMS2091P06
  • HMS2236I09
  • HMS3374P06
  • HMS502O11
  • HSDB 4161
  • HY-D0211
  • IDI1_000929
  • KBio1_000929
  • KBio2_001557
  • KBio2_004125
  • KBio2_006693
  • KBio3_001776
  • KBioGR_001383
  • KBioSS_001557
  • Koprol
  • Lax-Pills
  • Laxin
  • Laxogen
  • MFCD00005913
  • MLS000069592
  • MLS001148397
  • Medilax
  • NCGC00018200-01
  • NCGC00018200-02
  • NCGC00018200-03
  • NCGC00018200-04
  • NCGC00018200-05
  • NCGC00018200-06
  • NCGC00018200-07
  • NCGC00018200-08
  • NCGC00018200-09
  • NCGC00018200-10
  • NCGC00018200-12
  • NCGC00023694-03
  • NCGC00023694-04
  • NCGC00023694-05
  • NCGC00023694-06
  • NCGC00023694-07
  • NCGC00254039-01
  • NCGC00259768-01
  • NCI-C55798
  • NINDS_000929
  • NSC 10464
  • NSC-10464
  • NSC-215214
  • NSC-757271
  • NSC10464
  • NSC215214
  • NSC757271
  • Opera_ID_1337
  • P0094
  • P0700
  • P0701
  • P0702
  • Pharmakon1600-01500480
  • Phenolax
  • Phenolphtaleine
  • Phenolphthalein
  • Phenolphthalein (INN)
  • Phenolphthalein Paper, DAB 6
  • Phenolphthalein pH indicator solution
  • Phenolphthalein solution, 0.1 N
  • Phenolphthalein, pH indicator
  • Phenolphthalein,(S)
  • Phenolphthalein,white
  • Phenolphthalein,yellow
  • Phenolphthaleinum
  • Phenophthalein
  • Phillips Gelcaps
  • Phthalide 3,-bis(p-hydroxyphenyl)-
  • Phthalide 3,3,-bis(p-hydroxyphenyl)-
  • Phthalimetten
  • Phthalin
  • Purga
  • Purgen
  • Q-201555
  • Q187921
  • SBI-0051481.P003
  • SMP1_000235
  • SMR000059015
  • SPECTRUM1500480
  • SR-01000000112
  • SR-01000000112-2
  • STK029876
  • Spulmako-lax
  • Trilax
  • VS-01000
  • WLN: T56 BVO DHJ D- D-/R DQ 2
  • Yellow phenolphthalein
  • Z57233591
  • alpha-(p-Hydroxyphenyl)-alpha-(4-oxo-2,5-cyclohexadien-1-ylidene)-o-toluic acid
  • alpha-Di(p-hydroxyphenyl)phthalide
  • cid_4764
  • component of Agoral
  • component of Correctol
  • component of Feen-A-Mint Pills
  • phenolphtalein
  • phenolphthalein
  • s5395

Reference codes for other databases

There exist several different chemical codes commonly used in orded to identify molecules:
  • ZINC3831317
  • CAS-77-09-8
  • UNII-6QK969R2IF
  • AKOS000493033
  • BRD-K19227686-001-02-0
  • BRD-K19227686-001-12-9
  • DTXSID0021125
  • CHEMBL63857
  • CHEBI:34914
  • Tox21_110838
  • Tox21_202219
  • Tox21_300282
  • Tox21_110838_1
  • EINECS 201-004-7
  • SPBio_001278
  • SCHEMBL27670
  • Spectrum_001077
  • Spectrum2_001279
  • Spectrum3_000888
  • Spectrum4_000982
  • Spectrum5_001268

Physico-Chemical properties

IUPAC name3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one
Molecular formulaC20H14O4
Molecular weight318.323
Melting point (ºC)
Boiling point (ºC)
Density (g/cm3)
Molar refractivity88.67
Topological polar surface area66.8

LogP and topological polar surface area (TPSA) values were estimated using Open Babel software.

The n-octanol/water partition coeficient (Kow) data is applied in toxicology and drug research. Kow values are used, to guess the environmental fate of persistent organic pollutants. High partition coefficients values, tend to accumulate in the fatty tissue of organisms. Molecules with a log(Kow) (or LogP) greater than 5 are considered to bioaccumulate.

TPSA values are the sum of the surface area over all polar atoms or molecules, mainly oxygen and nitrogen, also including hydrogen atoms.

In medicinal chemistry, TPSA is used to assess the ability of a drug to permeabilise cells.

For molecules to penetrate the blood-brain barrier (and act on receptors in the central nervous system), TPSA values below 90 Å2 are required. Thus, molecules with a polar surface area greater than 140 Å2 tend to be poorly permeable to cell membranes.