Cresol sulfonephthalein

Bromocresol green Tetrabromo-m-cresol- sulfonephthalein Yellow Blue 3.8-S.4 4.7... 

Fortunately we are able to replace bromphenol blue and brom-cresol purple with other sulfonephthaleins which do not show dichromatism. W. C. Harden and N. L. Drake have prepared tetrabromophenoltetrabromosulfonephthalein (tetrabrom-phenol blue) which may be used in place of bromphenol blue. Both indicators have the same transformation range (pH 3.0-4.6) with a color change from pure yellow to pure blue. Chlor-phenol red, with a color change from yellow to red, is a good substitute for bromcresol purple. 

Dr. Klotz has found furthermore that the unbrominated sulfonephthaleins such as phenol red, cresol purple, thymol blue, etc., possess a marked tendency to form molecular compounds with their corresponding phenols. Apparently the stability of the indicator solutions depends upon this phenol content. 

A. Cohen has made use of mixtures of sulfonephthaleins. For example, a mixture of bromcresol purple and bromthymol blue is green-yellow at pH 6.0 and blue at 6.8. He recommends also solutions of bromcresol purple with bromphenol blue and of bromphenol blue and cresol red. Other combinations have also been proposed. I. M. Kolthofp has investigated a large... 

According to the previously cited reference (Hof nan, (1991), Appendix A), some dyelike materials show up as inhibitors of glutaminolysis. Thus, the agents listed as bromcresol (or bromocresol) green and bromcresol purple are dyes derived from sulfonephthalein, starting with the compound called mcto-cresol. Cresols in turn are related to phenol or carbolic acid, and to the coal-tar mixture called creosote. Phenolic-type compounds are also known to occur in chaparral or creosote bush (genus Larrea), hence its alternate common name. 

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