125-20-2

Basic information

• Product Name: Thymolphthalein
• Synonyms: 3,3-bis(4-hydroxy-2-methyl-5-(1-methylethyl)phenyl)-1(3H)-Isobenzofuranone;3,3-bis[4-hydroxy-2-methyl-5-(1-methylethyl)phenyl]-1(3h)-isobenzofuranon;thymolphtaleine;2',2''-DIMETHYL-5,5''-DI-ISO-PROPYLPHENOLPHTHALEIN;5',5''-DIISOPROPYL-2',2''-DIMETHYLPHENOLPHTHALEIN;5',5''-DIISOPROPYL-2',2''-DIMETHYLPHENOLPHTHALIEN;LABOTEST-BB LT00451890;TP
• CAS NO: 125-20-2
• Molecular Formula: C₂₈H₃₀O₄
• Molecular Weight: 430.54
• EINECS: 204-729-7
• Product Categories: Miscellaneous Biochemicals;Analytical Chemistry;Indicator (pH);pH Indicators;Phthalein
• Mol File: 125-20-2.mol

Chemical Properties

• Melting Point: 251-253 °C(lit.)
• Boiling Point: 504.79°C (rough estimate)
• Flash Point: 74 °F
• Appearance: White to slightly yellow/Low Melting Mass
• Density: 0.92 g/mL at 25 °C
• Vapor Pressure: 1.15E-13mmHg at 25°C
• Refractive Index: 1.6400 (estimate)
• Storage Temp.: Store at RT.
• Solubility: ethanol: clarity passes test
• PKA: 9.70, 10.0(at 25℃)
• Water Solubility: insoluble
• Merck: 14,9401
• BRN: 359413
• CAS DataBase Reference: Thymolphthalein(CAS DataBase Reference)
• NIST Chemistry Reference: Thymolphthalein(125-20-2)
• EPA Substance Registry System: Thymolphthalein(125-20-2)

Safety Data

• Hazard Codes: F,Xn
• Statements: 11-40-10
• Safety Statements: 7-16-36/37-24/25-22
• RIDADR: UN 1170 3/PG 3
• WGK Germany: 3
• TSCA: Yes
• HazardClass: 3
• PackingGroup: II
• Hazardous Substances Data: 125-20-2(Hazardous Substances Data)

Usage

Uses

Used in Chemical Laboratories:
Thymolphthalein is used as a pH indicator in chemical laboratories, where it changes color from colorless (pH 9.3) to blue (pH 10.5). This property makes it useful for determining the pH of solutions and monitoring acid-base reactions.
Used in Medical Applications:
Thymolphthalein is used as a reagent for blood analysis after decolorizing the alkaline solution by boiling with zinc dust. This process helps in the examination and diagnosis of various medical conditions.
Used in Saliva Testing:
Thymolphthalein is used in saliva testing as a pH-sensitive dye, which can help in assessing the acidity or alkalinity of saliva, providing insights into oral health and potential issues.
Used in Disappearing Ink Preparation:
Due to its color-changing properties, thymolphthalein is used in the preparation of disappearing ink. This ink is particularly useful in applications where temporary markings are required, such as in the entertainment industry or for security purposes.

InChI:InChI=1/C28H30O4/c1-15(2)20-13-23(17(5)11-25(20)29)28(22-10-8-7-9-19(22)27(31)32-28)24-14-21(16(3)4)26(30)12-18(24)6/h7-16,29-30H,1-6H3

Synthetic route

phthalic anhydride (85-44-9) + thymol (89-83-8) → thymolphthalein (125-20-2)

Conditions	Yield
With methanesulfonic acid at 90℃; for 5h;	90%
With niobium pentachloride In methanesulfonic acid at 90℃; for 1.33333h; Friedel-Crafts Acylation;	70%
With tin(IV) chloride at 110℃;

2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-glucopyranosyl chloride (3068-34-6, 38874-23-6, 41355-44-6, 51236-40-9, 74081-14-4, 79897-03-3, 100759-09-9, 109581-83-1) + thymolphthalein (125-20-2) → thymolphthalein-N-acetyl-3,4,6-O-triacetyl-β-D-glucopyranoside

Conditions	Yield
With tetra(n-butyl)ammonium hydrogensulfate; potassium carbonate In dichloromethane; water at 10 - 20℃; for 3h;	61.2%

thymolphthalein (125-20-2) + 1-bromo-2,3,4-tri-O-acetyl-α-D-glucuronic acid methyl ester (21085-72-3) → thymolphtaleine-α-acetyl-D-glucuronic acid methyl ester

Conditions	Yield
With tetra(n-butyl)ammonium hydrogensulfate; potassium carbonate In dichloromethane; water at 10 - 20℃; for 3h;	46.7%

thymolphthalein (125-20-2) + 1-bromo-2,3,4-tri-O-acetyl-α-D-glucuronic acid methyl ester (21085-72-3) → thymolphthalein β-D-glucuronide

Conditions	Yield
Stage #1: thymolphthalein; 1-bromo-2,3,4-tri-O-acetyl-α-D-glucuronic acid methyl ester With silver(l) oxide In methanol at 20℃; for 8h; Stage #2: With methanol; sodium hydroxide at 20℃; for 4h; Reagent/catalyst; Solvent;	35%

thymolphthalein (125-20-2) + acetic anhydride (108-24-7) → 3,3-bis-(4-acetoxy-5-isopropyl-2-methyl-phenyl)-phthalide

Conditions	Yield
With sulfuric acid; acetic acid

thymolphthalein (125-20-2) + methyl iodide (74-88-4) → 3,3-bis-(5-isopropyl-4-methoxy-2-methyl-phenyl)-phthalide

Conditions	Yield
With potassium carbonate; acetone

thymolphthalein (125-20-2) + zinc dust + KOH-solution → thymolphthalyne

Upstream product

• 85-44-9 phthalic anhydride 
• 89-83-8 thymol 

Downstream Products

• 301327-03-7 3,3-bis-(4-acetoxy-5-isopropyl-2-methyl-phenyl)-phthalide 

Related news

A specific fluorescent probe for zinc ion based on Thymolphthalein (cas 125-20-2) and it’s application in living cells09/08/2019

Many diseases are connected with chemical substances, zinc ion is most important ion in chemical substances, because zinc ion (Zn2+) has been shown extensively involved in various physiological and pathological processes. In this work, thymolphthalein with good biocompatibility was introduced, t...detailed

Relevant articles and documents

NbCl5 Promoted the Efficient Synthesis of Phthalein Derivatives: Optical Characterization and Solvatochromic Effect

Organic dyes derived from phthaleins have a large number of industrial applications and can be synthesized using a Lewis acid by Friedel–Crafts acylation, followed by an addition reaction to the carbonyl compound. This work aims to investigate the use of NbCl5 as a catalyst for the acylation reaction. The behavior of the phthalein derivatives in several solvents and when subjected to different pH conditions was studied. These compounds showed a color-changing effect depending on the pH and solvent, making them useful for applications as indicators. The phthaleins change their conformations depending on the condition of the medium. Photophysical studies of these compounds were carried out through their UV–Vis absorption spectra. Here, we show the umbrella-like conformation change of phthalein derivatives that depend on the solvent and the pH of the medium.

A facile synthesis of phthalein indicator dyes

The use of methanesulfonic acid offers a novel and highly efficient method for the synthesis of phthalein indicator dyes in excellent yields on an industrial scale.

AROMATIC ESTERS FOR MARKING OR TAGGING ORGANIC PRODUCTS

A compound represented by formula I is used as a marker for organic products. wherein Ar1 and Ar2 each independently represent a substituted or unsubstituted phenylene group or a substituted or unsubstituted naphthylene group; R1 represents a straight or branched chain alkyl group having 1 to 22 carbon atoms; R2 represents a hydrogen atom or a group of the formula C(O)R4 where R4 is a hydrogen atom or a straight or branched chain alkyl group having 1 to 22 carbon atoms; and R3 represents a hydrogen atom, a straight or branched chain alkyl group having 1 to 12 carbon atoms, a straight or branched chain alkoxy group having 1 to 12 carbon atoms, a hydroxyl group, or a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group; and Z represents a hydrogen atom or a group of atoms that combine with Ar2 or R3 to form a lactone ring.