Methylxylenol blue

Methylthymol blue and methylxylenol blue, prepared by the Mannich reaction from thymol-sulfonphthalein and p- xylenol blue respectively, have been intensively studied and resemble xylenol orange in many respects. If only one chelating group is introduced into cresol red, semi-xylenol orange results which is a common contaminant in XO and proves to be a more sensitive reagent for zirconium. 

Bis(carboxymethy1)amino-methyl]-3,3, 6 -trimethyl-4 -hydroxyfuchson-2 -sulfonic acid (Methylxylenol Blue)... 

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