Xylenolorange

3,3- bis (N, N-bis ( carboxymethyl) aminomethyl) kresolsulfonphthalein

• C31H32N2O13S
• C31H28N2Na4O13S (as tetrasodium salt)

Red-brown crystalline powder

• 672.66 g.mol -1
• 760.58 g · mol -1 ( as a tetrasodium salt)

Fixed

210 ° C.

Good in water ( 510 g · l-1 at 20 ° C, tetrasodium salt)

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Xylenol orange is a triphenylmethane dye and is a member of the sulfonphthaleins. It is the Sulfonanalogon to metalphthalein. It is used as an indicator in the complexometric.

Chemical Properties

Xylenol orange containing a sulfonic acid, the four carboxyl, amino and two two hydroxyl groups which can be protonated and deprotonated in each case. At pH ≈ 4.5 xylenol orange is in a lemon-yellow form. In this form, xylenol orange now forms with some multivalent metal ions to a faint red - rotviolettgefärbten complex is destroyed by addition of a stronger complexing agent such as EDTA again.

Use

Xylenol orange is used as a tetrasodium salt in the complexometric, especially in the bismuth and lead content determination as an indicator. Unlike Eriochrome black T, the titration is carried out in an acidic medium at pH ≈ 4-5. Furthermore, xylenol orange is used in biology to make remodeling processes in vivo in bone visible until it is incorporated into newly formed bone. Also, spectrum can be used for coloring of microcracks in the bone, since it binds to the free metal ions to the surface. Xylenol orange has its absorption maximum at about 546 nm and the emission maximum at 580 nm and these ions vary slightly depending on the bound.