1386. Bromcresol Green

Nomenclature

CAS number: 76-60-8
4,4′-(1,1-Dioxido-3H-2,1-benzoxathiol-3-ylidene)bis[2,6-dibromo-3-methylphenol]; 4,4′-(3H-2,1-benzoxathiol-3-ylidene)bis[2,6-dibromo-3-methylphenol] S,S-dioxide; α,α-bis(3,5-dibromo-4-hydroxy-o-tolyl)-α-hydroxytoluenesulfonic acid, γ-sultone; 3,3′,5,5′-tetrabromo-m-cresolsulfonphthalein; bromocresol green.
C21H14Br4O5S; mol wt 698.01.
C 36.13%, H 2.02%, Br 45.79%, O 11.46%, S 4.59%.

Description and references

Prepd by adding bromine to a suspension of m-cresolsulfonphthalein in glacial acetic acid: Clark, Lubs, J. Wash. Acad. Sci. 5, 610 (1915); 6, 481 (1916); J. Bacteriol. 2, 110 (1917); Cohen, Biochem. J. 16, 31 (1922); 17, 535 (1923); Cohen, Public Health Rep. 38, 814 (1923); 41, 3051 (1926); Proc. Soc. Exp. Biol. Med. 20, 124 (1922); Orndorff, Purdy, J. Am. Chem. Soc. 48, 2216 (1926).

Chemical structure

Properties

Minute, slightly yellow crystals from acetic acid, mp 218-219°. Sparingly sol in water. Readily sol in alcohol, ether, ethyl acetate. Fairly sol in benzene. Very sensitive to alkalies, tap water being sufficiently alkaline to give the characteristic blue-green color. pKa = 4.7. pH 3.8 yellow; pH 5.4 blue-green. To prepare a soln for use as pH indicator, dissolve 0.10 g in 7.15 ml N/50 NaOH and dil with water to 250 ml. To prepare a soln for use as indicator in volumetric work, dissolve 0.1 g in 250 ml alc.

Derivative

Sodium salt.

Nomenclature

CAS number: 62625-32-5
C21H13Br4NaO5S; mol wt 720.00.
C 35.03%, H 1.82%, Br 44.39%, Na 3.19%, O 11.11%, S 4.45%.

Use

As pH indicator. As selective inhibitor of anion transport in kidney physiology. In lithography.