Thymolphthalein

Synonym(s):5′,5′′-Diisopropyl-2′,2′′-dimethylphenolphthalein;Thymolphthalein

CAS NO.：125-20-2
Empirical Formula: C28H30O4
Molecular Weight: 430.54
MDL number: MFCD00005909
EINECS: 204-729-7
SAFETY DATA SHEET (SDS)
Update Date: 2025-01-27 09:38:02

What is Thymolphthalein?

Description

An alkaline solution of thymolphthalein in alcohol makes a very good disappearing ink. The solution starts out blue, but when it absorbs carbon dioxide from the air, carbonic acid is formed, neutralizing the alkaline solution and causing the blue color to vanish. The color returns when the ink spot is treated with an alkaline solution.

Chemical properties

white fine crystalline powder

The Uses of Thymolphthalein

Thymolphthalein is a pH sensitive dye that has multiple uses such as testing hydration and/or saliva testing.

The Uses of Thymolphthalein

As pH indicator: colorless 9.3 to blue 10.5. Also as reagent for blood after decolorizing the alkaline solution by boiling with zinc dust.

Definition

ChEBI: Thymophthalein is a terpene lactone.

General Description

Thymolphthalien is an acid-base indicator which is colourless in acidic form and deep blue in basic form. Acidic form retains hydrogen on each hydroxyl group. It is suitable in preparing disappearing ink.

Synthesis

Thymolphthalein can be synthesized from thymol and phthalic anhydride.

Properties of Thymolphthalein

Melting point:	251-253 °C(lit.)
Boiling point:	504.79°C (rough estimate)
Density	0.92 g/mL at 25 °C
vapor pressure	0.002Pa at 90℃
refractive index	1.6400 (estimate)
Flash point:	74 °F
storage temp.	no restrictions.
solubility	ethanol: clarity passes test
form	Low Melting Mass
pka	9.70, 10.0(at 25℃)
color	White to slightly yellow
Specific Gravity	0.92
PH	8.6～10.5
PH Range	9.3(colourless)-10.5(blue)
Odor	Mild characteristic odor
explosive limit	3.30-19%
Water Solubility	insoluble
λmax	592nm, 396nm, 598nm
Merck	14,9401
BRN	359413
Major Application	Display device, semiconductors, recording materials, photoconductors, sol-gel matrix, tin electroplating process, counterfeit-proof paper, authentication system forsecure documents, inks, pencil leads, correction fluid, paints, petroleum marker, tennis ball, adhesives, floor coatings, textiles, detergents, insecticide, lotion, cleaning pads, food storage, determine bacterial growth, Streptococci in saliva, dental impressionmaterials
CAS DataBase Reference	125-20-2(CAS DataBase Reference)
EPA Substance Registry System	Thymolphthalein (125-20-2)

Safety information for Thymolphthalein

Signal word	Danger
Pictogram(s)	Flame Flammables GHS02 Health Hazard GHS08
GHS Hazard Statements	H225:Flammable liquids H313:Acute toxicity,dermal H333:Acute toxicity,inhalation H371:Specific target organ toxicity, single exposure
Precautionary Statement Codes	P210:Keep away from heat/sparks/open flames/hot surfaces. — No smoking. P260:Do not breathe dust/fume/gas/mist/vapours/spray. P303+P361+P353:IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower. P405:Store locked up.