Naphtholphthalein

Naphtholphthalein
Names


IUPAC name 3,3-bis(4-hydroxynaphthalen-1-yl)-2-benzofuran-1-one
Other names 1-Naphtholphthalein, alpha-naphtholphthalein, naphtholphthalein blue
Identifiers
CAS Number	596-01-0^Y
Beilstein Reference	97816
ChemSpider	62215^N
Jmol interactive 3D	Image
PubChem	68993
SMILES C1=CC=C2C(=C1)C(=CC=C2O)C3(C4=CC=CC=C4C(=O)O3)C5=CC=C(C6=CC=CC=C65)O
Properties
Chemical formula	C₂₈H₁₈O₄
Molar mass	418.45 g·mol⁻¹
Appearance	Colorless-reddish to blue-green solid
Melting point	238–240 °C (460–464 °F; 511–513 K) ^[1]
Solubility in water	Insoluble
Hazards
Main hazards	Irritant
GHS pictograms	^[1]
GHS signal word	Warning
GHS hazard statements	H315, H319, H335^[1]
GHS precautionary statements	P261, P305+351+338^[1]
EU classification (DSD)	Xi
R-phrases	R36/38, R36/37/38
S-phrases	S26, S36, S37/39
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is ^YN ?)
Infobox references

α-Naphtholphthalein (C₂₈H₁₈O₄) is a pH indicator with a visual transition from colorless/reddish to greenish/blue at pH 7.3–8.7.

Naphtholphthalein (pH indicator)
below pH 7.3		above pH 8.7
7.3	⇌	8.7

References

1 2 3 4 α-Naphtholphthalein

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