Cresol phthalein

Metalphthalein (H2O) [2411-89-4] M 636.6, m 186. Dissolved in sodium acetate and fractionally ppted with HCI. This removed unsubstituted and monosubstituted cresol phthaleins (which separated at lower acidities). Washed with cold water, dried to mononhydrate at 30° in vacuo. 

Calcium can be estimated by its formation with cresol-phthalein complexone to form a coloured complex. 8-Hydroxyquinoline can be added to bind magnesium and prevent interference from this ion. Other complexing agents have been tried, e.g. methylthymol blue. This type of method is used in many continuous flow and discrete analysers. 

Similarly o-sulphobeiizoic anhydride and o-cresol yields o-cresolsulphone-phthalein (o-cresol red) dibromination of the last-named gives dibromo-o-sulphonephthaleln (bromocresol purple) ... 

Meta cresol purple m-Cresolsulphone-phthalein Red Yellow 1-2-2-8... 

Cresol red (base) o-Cresol-sulphone-phthalein Yellow Red 7-2-88... 

The pH required for the precipitation of C is about 5-5 this can be more conveniently achieved by the use of either nitrazine (sodium dinitrophenyl-azo-naphthol sulphonate) or bromocresol purple (dibromo-o-cresol-sulphone-phthalein) test-papers. All that is necessary is to add the sodium hydroxide solution until the appropriate colour change is produced it is best to use a... 

F) Preparation of Sulfonphthaleins. The preparations described involve (1) hydrolysis of o-sulfobenzoic imide (saccharin) to the ammonium salt of o-sulfobenzoic acid (2) preparation of o-sulfo-benzoic anhydride (3) preparation of phenolsulfonphthalein (phenol red) (4) bromination of phenolsulfonphthalein to tetrabromo derivative (bromophenol blue) (5) preparation of o-cresolsulfon-phthalein (cresol red) (6) bromination of o-cresolsulfonphthalein to the dibromo derivative (bromocresol purple)The equations for the steps are ... 

Facile and rapid polycondensation reactions of N,N -(pyromellitoyl)-bis-L-leucine diacid chloride, N,N -(pyromellitoyl)-bis-L-phenylalanine diacid chloride, 4,4 -earbonyl-bis(phthaloyl-L-alanine) diacid chloride or 4,4 -(hexafluoroisopropylidene)-N,N -bis(phthaloyl-Lleucine) diacid chloride with several aromatic diols such as phenol phthalein, bisphenol-A, 4,4 -hydroquinone, l,8-dihydro5g anthraquinone, 1,5-dihydroxy naphthalene, 4,4-dihydroxy biphenyl and 2,4-dihydroxyacetophenone were reported by using a domestic microwave oven in the presence of a small amount of a polar otganic solvent such as o-cresol (Mallakpour and Habibi, 2003). The polymerization reactions occurred rapidly and are completed within 10-20 min, producing a series of optically active poly(ester-imide)s with good yields and moderate inherent viscosities. 

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