Bromocresol green

From Sciencemadness Wiki
Jump to: navigation, search
Bromocresol green
Bromocresol green sample solution.jpg
Bromocresol green in solid form and as solution at pH < 3.8 (yellow), pH 3.8-5.4 (green) and pH > 5.4 (blue)
Names
Other names
3,3′,5,5′-Tetrabromo-m-cresolsulfonphthalein
Properties
C21H14Br4O5S
Molar mass 698.01 g/mol
Appearance Light brown powder
Odor Odorless
Melting point Decomposes
Boiling point 225 °C (437 °F; 498 K) (decomposes)
Sparingly soluble
Solubility Very soluble in acetone, aq, ammonia, diethyl ether, ethanol
Soluble in benzene
Sparingly soluble in chloroform, isopropanol
Insoluble in glycerol, hexane
Vapor pressure ~0 mmHg
Acidity (pKa) 4.90
Hazards
Safety data sheet AcrosOrganics
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Bromocresol green (IUPAC: 2,6-dibromo-4-[7-(3,5-dibromo-4-hydroxy-2-methyl-phenyl)-9,9-dioxo-8-oxa-9λ6-thiabicyclo[4.3.0]nona-1,3,5-trien-7-yl]-3-methyl-phenol) is an organic chemical compound, used as a dye and pH indicator in applications such as growth mediums for microorganisms and titrations. It has the formula C21H14Br4O5S.

Properties

Chemical

Bromocresol green will turn yellow at low pH and blue at high pH.

Physical

Bromocresol green is a light brown powder, almost insoluble in water, but more soluble in organic solvents such as acetone, diethyl ether or ethanol.

Availability

Can be purchased from chemical suppliers or online.

Preparation

Best to purchase it.

Projects

  • pH indicator
  • Tracking dye

Handling

Safety

Bromocresol green may stain, though its low water solubility limits this effect. No data is currently available for its toxicity.

Storage

Bromocresol green is best kept in closed bottles, away from acids and ammonia.

Disposal

Adding a strong oxidizing solution, such as chromic acid, Fenton's reagent or piranha solution will slowly break it down to carbon dioxide, water, sulfur dioxide and bromine. Neutralize it with an alkaline base and then pour it down the drain.

References

Relevant Sciencemadness threads