Xylenol orange

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Xylenol orange
IUPAC name	3,3′-Bis[N,N-bis(carboxymethyl)aminomethyl]-o- cresolsulfonephthalein tetrasodium salt
Identifiers
CAS number	[3618-43-7]
Properties
Molecular formula	C31H28N2O13SNa4
Molar mass	760.59 g mol−1
Melting point	195°C (368 K)
Solubility in water	Fully miscible
Hazards
NFPA 704	1 2 2
R-phrases	R10, R20, R21, R22, R36, R38
S-phrases	(S1/2), S26, S27, S28, S62, S63
Flash point	Greater than 93.3°C (200°F)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Xylenol orange is an organic reagent, most commonly used as a tetrasodium salt as an indicator for metal titrations. Historically, commercial preparations of it have been notoriously impure, sometimes consisting of as little as 20% xylenol orange, and containing large amounts of semi-xylenol orange and iminodiacetic acid. Purities as high as 90% are now available.