Semi-Methylthymol Blue

Bis(carboxymethyl)aminomethyl-3,3 -bis(methylethyl)-6,6 -dimethyl-4 -hvdroxvfuchson-2" sulfonic acid (Semi-Methylthymol Blue)... 

A variety of papers on substitution reactions at aluminium(iii) in aqueous media have appeared. Complexation with 5-nitrosalicylic acid has been studied and compared with related studies involving other salicylic acid derivatives. It seems possible that the substitution process may be associative in character. There has been an investigation of the kinetics and equilibria of the reactions with Semi-xylenol Orange and Semi-methylthymol Blue. The latter two reactions involve a pre-equilibrium step, followed by a substitution stage in which several outer-sphere water molecules are removed. The relative reactivities of three different reaction pathways are [HaL]"- -[A10H] +> [HaL] "- -[A10H] +> [HaL] -- -Al +. The kinetics of complexation of aluminium(iii) with fluoride are... 

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. 

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