Xylenol orange

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Structural formula
Structural formula of xylenol orange
General
Surname Xylenol orange
other names

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

Molecular formula
  • C 31 H 32 N 2 O 13 S
  • C 31 H 28 N 2 Na 4 O 13 S (as tetrasodium salt)
Brief description

red-brown crystalline powder

External identifiers / databases
CAS number
  • 1611-35-4
  • 3618-43-7 (as tetrasodium salt)
EC number 216-553-8
ECHA InfoCard 100.015.049
PubChem 73041
ChemSpider 65838
Wikidata Q286281
properties
Molar mass
  • 672.66 g mol −1
  • 760.58 g mol −1 (as tetrasodium salt)
Physical state

firmly

Melting point

210 ° C

solubility

good in water (510 g l −1 at 20 ° C, tetrasodium salt)

safety instructions
GHS labeling of hazardous substances
no GHS pictograms
H and P phrases H: no H-phrases
P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Xylenol orange is a triphenylmethane dye and belongs to the group of sulfonphthaleins . It is the sulfone analog of metal phthalein . It is used as an indicator in complexometry .

Chemical properties

Solid xylenol orange and aqueous xylenol orange solution at pH = 4.5.

Xylenol orange contains one sulfonic acid, four carboxy , two amino and two hydroxyl groups , each of which can be protonated or deprotonated. At pH  ≈ 4.5, xylenol orange is in a lemon yellow form. In this form, xylenol orange now forms a weak red to red-violet colored complex with some multivalent metal ions , which is destroyed again by adding a stronger complexing agent such as EDTA .

use

Xylenol orange is used as a tetrasodium salt in complexometry, especially as an indicator for determining the bismuth and lead content . In contrast to Eriochrome black T , the titration takes place in an acidic medium at pH ≈ 4–5. Xylenol orange is also used in biology to make remodeling processes in vivo visible in bones , as it is stored in newly formed bones. It can also be used to color microcracks in bones, as it binds to the free metal ions on the surface. Xylenol orange has its absorption maximum at about 546 nm and the emission maximum at 580 nm, these changing slightly depending on the bound ions.

literature

  • E. Merck (Ed.): Complexometric determinations with Titriplex. Darmstadt.

Individual evidence

  1. ↑ a b Entry on xylenol orange. In: Römpp Online . Georg Thieme Verlag, accessed on December 29, 2014.
  2. ↑ a b c data sheet xylenol orange tetrasodium salt (PDF) from Merck , accessed on December 25, 2019.
  3. ↑ Xylenol orange data sheet from Acros, accessed December 25, 2019.
  4. ↑ Lecture notes on complexometry (PDF; 80 kB).
  5. ^ University of Leipzig, Institute for Analytical Chemistry: Selected Titrations ( Memento from April 25, 2012 in the Internet Archive )
  6. Jump up ↑ Berton A. Rahn, Stephan M. Perren: Xylenol Orange, A Fluorochrome Useful in Polychrome Sequential Labeling of Calcifying Tissues. In: Stain Technology . 46, 1971, pp. 125-129; doi: 10.3109 / 10520297109067836 .
  7. ^ TC Lee, TL Arthur, LJ Gibson, WC Hayes: Sequential labeling of microdamage in bone using chelating agents. In: Journal of Orthopedic Research . 18, 2000, pp. 322-325; doi: 10.1002 / jor.1100180222 .
  8. ↑ Olympus Fluorochrome Table ( Memento from March 4, 2011 in the Internet Archive )

Web links

Commons : Xylenolorange  - Collection of images, videos, and audio files