Synthesis of phenolphthalein

Preparation of phenolphthalein

Preparation of phenolphthalein

Preparation of phenolphthalein

A solution of 250 g of phthalic anhydride in 200 g of concentrated sulfuric acid is prepared with careful heating. It is cooled to 115° C, and treated with 500 g of phenol, and the mixture is then heated at 115-120° C for 10-12 hours, care being taken that the temperature does not exceed 120° C. The reaction mixture is then poured into boiling water, and the excess of phenol removed by steam distillation. The granular yellow solid is extracted with dilute caustic soda, which dissolves out the phenolphthalein, leaving behind a by-product, phthalein anhydride. After cooling, the liquid is filtered, acidified with acetic acid, mixed with a few drops of hydrochloric acid, and left to stand for 24 hours. The crude phenolphthalein, a sandy yellow powder, is then filtered off and dried. The further purification of phenolphthalein is performed by crystallization. 10 g of the air-dried crude phenolphthalein are boiled under reflux for 90 minutes with 60 g of absolute alcohol and 5 g of activated charcoal to two-thirds their original volume, and treated with water. The milky liquid deposits, on standing, crystals of phenolphthalein mixed with a gummy impurity. To remove this, the alcoholic solution is added to water, in the proportion of 40 grams to 320 ml the mixture is vigorously shaken, and after standing for a short time separated quickly from the precipitated resin. The solution is then heated, when the milkiness disappears, a white crystalline powder being precipitated. This is filtered off, washed with water, and dried at a low temperature. A further quantity is obtained by removal by distillation of the alcohol from the filtrate. The yield of phenolphthalein is 75 %, calculated from the weight of phthalic anhydride employed. Phenolphthalein forms a white powder, almost insoluble in water; readily soluble in alcohol. It melts at 250-253° C and dissolves completely in sodium or potassium hydroxide solution.

Organic medical chemicals, by M. Barrowliff, 209-210, 1921





InChI Key


Canonical SMILES


MeSH Synonyms

Ap-La-Day, Ex-Lax, Feen-A-Mint, Key Brand of Phenolphthalein, Laxatone, Laxettes, Manesco Brand of Phenolphthalein, Mentholatum Brand of Phenolphthalein, Modane, Novartis Brand of Phenolphthalein, Phenolphthalein, Schering-Plough Brand of Phenolphthalein, Thalinol, Thompson Brand of Phenolphthalein

Depositor-Supplied Synonyms

phenolphthalein, 77-09-8, Euchessina, Phthalimetten, Chocolax, Espotabs, Laxogen, Phenolax, Purgophen, Koprol, Purga, Trilax, Lilo, Spulmako-lax, Ex-Lax, Feen-A-Mint Gum, Phthalin, Purgen, 3,3-Bis(4-hydroxyphenyl)phthalide, Evac-Q-Kwik, Evac-Q-Kit, Evac-U-Gen, Fenolftalein, Alophen, Correctol, Doxidan, Medilax, Agoral, Colax, Dihydroxyphthalophenone, Laxin, FemiLax, 3,3-Bis(p-hydroxyphenyl)phthalide, Phillips Gelcaps, Lax-Pills, Evac-Q-Tabs, Evac-V-Lax, Fenolftalein [Czech], 3,3-Bis(4-hydroxyphenyl)-1(3H)-isobenzofuranone, 1(3H)-Isobenzofuranone, 3,3-bis(4-hydroxyphenyl)-, Fenolftaleina, Phenolphtaleine, Phenophthalein, Phenolphthaleinum, NCI-C55798, Feen-A-Mint Laxative Mints, component of Agoral, Fenolftaleina [INN-Spanish], Phenolphtaleine [INN-French], Phenolphthaleinum [INN-Latin], 3,3-Bis(4-hydroxyphenyl)isobenzofuran-1(3H)-one, 3,3-Bis(4-hydroxyphenyl)-2-benzofuran-1(3H)-one, alpha-Di(p-hydroxyphenyl)phthalide, NSC 10464, Phthalide 3,3,-bis(p-hydroxyphenyl)-, CHEMBL63857, CCRIS 6266, CHEBI:34914, HSDB 4161, KJFMBFZCATUALV-UHFFFAOYSA-N, EINECS 201-004-7, component of Correctol, BRN 0284423, NCGC00018200-07, Phenolphthalein solution, AI3-09081, 3,3-bis(4-hydroxyphenyl)isobenzofuran-1-one, DSSTox_CID_1125, DSSTox_RID_75956, DSSTox_GSID_21125, component of Feen-A-Mint Pills, Laxettes, Phthalide 3,-bis(p-hydroxyphenyl)-, Feen-a-mint, alpha-(p-Hydroxyphenyl)-alpha-(4-oxo-2,5-cyclohexadien-1-ylidene)-o-toluic acid, CAS-77-09-8, SMR000059015, WLN: T56 BVO DHJ D- D-/R DQ 2, 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one, 1(3H)-Isobenzofuranone,3-bis(4-hydroxyphenyl)-, 3,3-bis(4-hydroxyphenyl)-3-hydroisobenzofuran-1-one, phenolphtalein, Figsen, Laxett es, Doxan (Salt/Mix), Phenolphthalein,white, Agoral (Salt/Mix), Modane (TN), Phenolphthalein Paper, Laxcaps (Salt/Mix), Phenolphthalein,yellow, PubChem7084, Phenolphthalein (INN), Spectrum_001077, AC1L1IWH, Spectrum2_001279, Spectrum3_000888, Spectrum4_000982, Spectrum5_001268, Modane Plus (Salt/Mix), PHENOLPHTHALEIN, ACS, Phenolphthalein [INN:BAN], SCHEMBL27670, BSPBio_002518, KBioGR_001383, KBioSS_001557, MLS000069592, MLS001148397, BIDD:ER0202, Bio-0349, DivK1c_000929, SPECTRUM1500480, SPBio_001278, 16019_RIEDEL, 33518_RIEDEL, 34605_RIEDEL, 34606_RIEDEL, 34607_RIEDEL, 37167_RIEDEL, 6QK969R2IF, AC1Q78Q2, ARONIS002962, P9750_SIAL, 33518_SIGMA, 34605_FLUKA, 34606_FLUKA, 34607_FLUKA, BCBcMAP01_000174, HMS502O11, KBio1_000929, KBio2_001557, KBio2_004125, KBio2_006693, KBio3_001776, MolPort-001-011-548, NINDS_000929, 16019_SIAL, HMS1920H04, HMS2091P06, HMS2236I09, HMS3374P06, LS-47, Pharmakon1600-01500480, component of Correctol (Salt/Mix), 105945_SIAL, 319236_SIAL, C20H14O4, NSC10464, Tox21_110838, Tox21_202219, Tox21_300282, BBL002030, CCG-39112, NSC-10464, NSC215214, NSC757271, PHENOLPHTHALEIN U.S.P./N.F., SBB008868, STK029876, ZINC03831317, AKOS000493033, Tox21_110838_1, DB04824, MCULE-5232154932, NE46883, NSC-215214, NSC-757271, RL04943, IDI1_000929, SMP1_000235, NCGC00018200-01, NCGC00018200-02, NCGC00018200-03, NCGC00018200-04, NCGC00018200-05, NCGC00018200-06, NCGC00018200-08, NCGC00018200-09, NCGC00018200-10, NCGC00018200-12, NCGC00023694-03, NCGC00023694-04, NCGC00023694-05, NCGC00023694-06, NCGC00023694-07, NCGC00254039-01, NCGC00259768-01, AC-14431, AJ-45783, AK130019, AN-23907, BP-30100, ST072636, component of Feen-A-Mint Pills (Salt/Mix), TR-037762, 2-[Bis (4-hydroxyphenyl)methyl]benzoic acid, EU-0082600, FT-0659094, P0094, P0700, P0701, P0702, ST24041105, T8172, EN300-92962, .alpha., .alpha.-Di(p-hydroxyphenyl)phthalide, C14286, D05456, 5-18-04-00188 (Beilstein Handbook Reference), 3,3-bis[4-Hydroxyphenyl]-1-[3H]-isobenzofuranone, I01-9729, I06-1896, TRANSGENIC MODEL EVALUATION (PHENOLPHTHALEIN), 3,3-Bis(4-hydroxyphenyl)-2-benzofuran-1(3H)-one #, 3,3-bis[4-Hydroxyphenyl]-1-[3H]- isobenzofuranone, BRD-K19227686-001-02-0, TRANSGENIC MODEL EVALUATION II (PHENOLPHTHALEIN), 3,3-bis(4-hydroxyphenyl)-1,3-dihydro-2-benzofuran-1-one, 390417-24-0, 467-29-8, 546094-13-7, 57214-20-7, InChI=1/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/h1-12,21-22

Removed Synonyms

Laxcaps, Modane, Doxan, Modane Plus, Laxatone, Thalinol, Prulet, Mixture Name, Ap-La-Day, Key Brand of Phenolphthalein, UNII-6QK969R2IF, Manesco Brand of Phenolphthalein, CID4764, Novartis Brand of Phenolphthalein, Thompson Brand of Phenolphthalein, Mentholatum Brand of Phenolphthalein, Schering-Plough Brand of Phenolphthalein, D020113

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