Xylenol orange

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Xylenol orange
CAS number 1611-35-4 YesY
3618-43-7 (tetrasodium salt)
PubChem 73041
ChemSpider 65838 YesY
EC-number 216-553-8
Jmol-3D images Image 1
Molecular formula C31H32N2O13S
Molar mass 672.66 g mol−1
Melting point 195 °C (383 °F; 468 K)
Solubility in water 200 mg/mL
EU Index not listed
R-phrases R10, R20, R21, R22, R36, R38
S-phrases (S1/2), S26, S27, S28, S62, S63
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point > 93 °C (200 °F)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Xylenol orange is an organic reagent, most commonly used as a tetrasodium salt as an indicator for metal titrations. When used for metal titrations it will appear red in the titrand and yellow once it reaches its endpoint. Historically, commercial preparations of it have been notoriously impure,[1] 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.


  1. ^ Gay, Craig; Collins, James; Gebicki, Janusz M. (1999), Determination of Iron in Solutions with the Ferric–Xylenol Orange Complex, Analytical Biochemistry 273 (2): 143–148, doi:10.1006/abio.1999.4207