Bromcresol Green

Title: Bromcresol Green
CAS Registry Number: 76-60-8
CAS Name: 4,4¢-(3H-2,1-Benzoxathiol-3-ylidene)bis[2,6-dibromo-3-methylphenol] S,S-dioxide
Additional Names: a,a-bis(3,5-dibromo-4-hydroxy-o-tolyl)-a-hydroxytoluenesulfonic acid, g-sultone; 3,3¢,5,5¢-tetrabromo-m-cresolsulfonphthalein
Molecular Formula: C21H14Br4O5S
Molecular Weight: 698.01
Percent Composition: C 36.13%, H 2.02%, Br 45.79%, O 11.46%, S 4.59%
Literature 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).
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. pK = 4.7. 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.
Melting point: mp 218-219°
pKa: pK = 4.7
Use: As indicator, pH 3.8 yellow; pH 5.4 blue-green.
Bromcresol Purple Bromelain Bromfenac Bromhexine Bromic Acid