Bromocresol Green

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Structural formula
Structural formula of bromocresol green
Structural formula as Sulton
General
Surname Bromocresol Green
other names
  • Bromocresol Blue
  • 3,3 ', 5,5'-tetrabromo- m -cresolsulfonphthalein
  • BCG
Molecular formula C 21 H 14 Br 4 O 5 S
Brief description

green solid

External identifiers / databases
CAS number 76-60-8
EC number 200-972-8
ECHA InfoCard 100,000,885
PubChem 6451
Wikidata Q418613
properties
Molar mass 698.04 g mol −1
Physical state

firmly

density

0.78 g cm −3

Melting point

225 ° C (dec.)

solubility
  • as the monosodium salt 4% in water and 6% in ethanol
  • as sultone practically insoluble in water (0.6%) and 4% in ethanol
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 .

Bromocresol green (also bromocresol blue ) is a triphenylmethane dye and belongs to the group of sulfonphthaleins. It can be represented by bromination of cresol purple . The soluble sodium salt is a pH indicator .

Properties and use

The sultone has an excitation maximum at 423  nm in methanol and the sodium salt dissolved in water at 617 nm.

Bromocresol green changes from yellow to green to deep blue in the pH range 3.8–5.4. The pKa value is 4.90. In the literature, the pKa value is also given as 4.6.

In acid-base titration , it is used as an indicator in the acidic range. It also shows the transition point when detecting ammonium according to Kjeldahl and when determining the carbonate hardness by titration with hydrochloric acid. It is approved as a coloring agent for cosmetics and is also used as a dye marker in agarose gel electrophoresis of DNA .

In 1958, bromocresol green was first used in studies of the permeability of the brain-blood barrier. It is also used as a selective inhibitor of the anion transporter in the kidney.

It is also used as a spray reagent for the detection of organic acids in thin layer chromatography .

literature

  • Richard W. Horobin, John A. Kiernan: Conn's Biological Stains: A Handbook of Dyes, Stains and Fluorochromes for Use in Biology and Medicine. 10th edition. BIOS Scientific Publ., Oxford 2002, ISBN 1-85996-099-5 , p. 217.

Web links

Commons : Bromocresol Green  - Collection of images, videos, and audio files

Individual evidence

  1. ↑ a b c d data sheet bromocresol green (PDF) from Carl Roth , accessed on September 16, 2018.
  2. ↑ a b Datasheet Bromocresol Green from Sigma-Aldrich , accessed on September 16, 2018 ( PDF ).
  3. ↑ Santa Cruz Biotechnology: Bromocresol green, sodium salt .
  4. ↑ Santa Cruz Biotechnology: Bromocresol green .
  5. ↑ chem.wisc.edu: pKa Data , Compiled by R. Williams (PDF, 78 kB).
  6. ↑ Richard W. Horobin, John A. Kiernan: Conn's Biological Stains: A Handbook of Dyes, Stains and Fluorochromes for Use in Biology and Medicine. 10th edition. BIOS Scientific Publ., Oxford 2002, ISBN 1-85996-099-5 , p. 217.
  7. ↑ Reinhard Mattisek, Gabriele Steiner, Markus Fischer: Food Analysis . 4th edition. Springer, Berlin 2010, ISBN 978-3-540-92205-6 .