Cresol red

Other Names Phenol, 4,4 -(3H-2,l-benzoxathiol-3-ylidene)fci5 [2-methyl-, 5, 5-dioxide o-Cresol, 4,4 -(3H-2,l-benzoxathiol-3-ylidene)di-, 5,5-dioxide o-Cresolsulfonephthalein o-Toluenesul-fonic acid, a-hydroxy-a,a- (4-hydroxy-m-tolyl)-, y-sultone 3H-2,l-Benzoxathiole, phenol derivative 3, 3 -Dimethylphenolsulfonephthalein Cresol red Cresolsnlfophthalein NSC 7224 o-Cresol Red o-Cresolsulfonphthalein 

CA Index Name Phenol, 4,4 -(l,l-dioxido-3H-2,l-benzoxathiol-3-ylidene)fc [2-methyl-CAS Registry Number 1733-12-6 Merck Index Number 2578 Chemical Structure 

Chemical/Dye Class Sulfonephthalein Molecular Formula C21H18O5S Molecular Weight 382.43 pH Range 0.2-1.8 

Physical Form Green glittering crystals or reddish-brown powder Solubility Sparingly soluble in water soluble in ethanol UV-Visible ( max) 570 nm, 367 nm, 432 nm Melting Point 300°C 

Boiling Point (Calcd.) 561.9 + 50.0°C Pressure 760 Torr Synthesis Synthetic methodsi-5 

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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) ... 

Sulphonphthaleins. These indicators are usually supplied in the acid form. They are rendered water-soluble by adding sufficient sodium hydroxide to neutralise the sulphonic acid group. One gram of the indicator is triturated in a clean glass mortar with the appropriate quantity of 0.1 M sodium hydroxide solution, and then diluted with water to 1 L. The following volumes of 0.1 M sodium hydroxide are required for 1 g of the indicators bromophenol blue, 15.0 mL bromocresol green, 14.4 mL bromocresol purple, 18.6 mL chlorophenol red, 23.6 mL bromothymol blue, 16.0 mL phenol red, 28.4 mL thymol blue, 21.5 mL cresol red, 26.2 mL metacresol purple, 26.2 mL. 

Procedure B. The experimental details for the preparation of the initial solution are similar to those given under Procedure A. Titrate 25 or 50 mL of the cold solution with standard 0.1M hydrochloric acid and methyl orange, methyl orange-indigo carmine, or bromophenol blue as indicator. Titrate another 25 or 50 mL of the cold solution, diluted with an equal volume of water, slowly with the standard acid using phenolphthalein or, better, the thymol-blue cresol red mixed indicator in the latter case, the colour at the end point is rose. Calculate the result as described in the Discussion above. 

In the second procedure a portion of the cold solution is slowly titrated with standard 0.1M hydrochloric acid, using phenolphthalein, or better, the thymol blue-cresol red mixed indicator. This (say, YmL) corresponds to half the carbonate (compare Section 10.32) ... 

Mixed indicator. This should be prepared from 1 part of 0.1 per cent neutralised aqueous cresol red and 3 parts of 0.1 per cent neutralised thymol blue. 

Xylenolorange. This indicator is 3,3 -bis[ IV,/V-di(carboxy methyl Jaminomethyl]-o-cresolsulphonphthalein it retains the acid-base properties of cresol red and displays metal indicator properties even in acid solution (pH = 3-5). Acidic solutions of the indicator are coloured lemon-yellow and those of the metal complexes intensely red. 

Figure 11. Absorption spectra of gel-immobilized cresol red after immersion in different pH buffer solutions (3, 4, 5, 6, 7, 8, 9, 10) for 1 min. Films prepared from TEOS MTMOS (2 1) sol.

Representative absorption spectra for cresol red in a 2 1 tetraethoxysilane (TEOS) methyltrimethoxysilane (MTMOS) film after immersion in buffer solutions of varying pH can be seen in Figure 11. The absorbance for gel-immobilized cresol red at 570 nm increases with increasing pH. Isosbestic points can be observed at ca. 480 nm for gel-immobilized cresol red. 

Methyl violet Cresol red Thymol blue Methyl orange Bromcresol green Methyl red Bromthymol blue Phenolphthalein Thymolphthalein Clayton yellow... 

Buryak and Severin have described the use of dynamic libraries of Cu(II) and Ni(II) complexes as sensors for tripeptides [61]. A notable aspect of this work is that as isolation of the metal complexes is not necessary (sensing is accomplished by observing changes in the UV-vis spectrum), potential concerns over the lability of coordination complexes do not apply. Specifically, three common dyes [Arsenazo I (41), Methyl Calcein Blue (42), and Glycine Cresol Red (43), Fig. 1.18] were mixed with varying ratios and total concentrations of Cu(II) and Ni(II) salts in a 4X5 array. Previous work had demonstrated that these conditions produced equilibrating mixtures of 1 1 and 2 1 homo- and heteroleptic complexes [62], These arrays were able to clearly and unambiguously differentiate tripeptides based on the differential pattern of response. The Severin laboratory has... 

Dissolve samples in buffer G. Electrode buffer is Soln H. Applied voltage should be 8 -10 V per centimeter of gel length. Tracking dye has to be an anionic one intensively colored at pH 2.4 (e.g., cresol red or Pyronin Y). 

Cresol red Crystal Violet Malachite Green Methanil Yellow Thymol Blue Orange IV -2,4-Dinitrophenol -Erythrosin, Na2 salt -Dimethyl Yellow Cl 11020 Bromophenol Blue Congo Red Cl 22120 Methyl Orange Bromocresol Green Alizarin Red S Cl 42750 Methyl Red Cl 13020 -Bromocresol Purple Chlorophenol Red p-Nitrophenol Alizarin Bromothymol Blue Brillant Yellow Phenol Red Neutral Red Cl 50040 -m-NItrophenol -Cresol Red Metacresol Purple Phenolphthalein -Thymolphthalein -P-Naphthyl Violet Alizarin Yellow R 2,4,6-T rinitrotoluene... 

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