Triphenyl blue

In 1860, Girard and de Laire heated fuchsin with aniline and found triphenyl-fuchsin, known as Lyon Blue. Nicholson, in an attempt to make this structure water soluble, in 1862 introduced free sulfonic acid groups into the molecule through sulfonation. 

Addition of a few drops of 60% perchloric or cone, sulfuric acid to a solution of 2.4.6-triphenyl-X -phosphorin 22 affords a deep blue compound which is soluble in polar solvents. This new compound is not the protonated form of the X -phosphorin, but rather a cation which results from oxidation of the X -phosphorin (see p. 50). 

The formation of blue cations like 73 is a very general type of reaction. It can be used as a characteristic reaction with all 2.4.6-aryl-substituted X -phospha-cyclohexadiene compounds with an OH or OR group at position 2 or 4. An analogous reaction is well known from experiments with 2.4.6-triphenyl-4-hydroxy-(or alkoxy) cyclohexadiene(2,5)-one 76 which also gives a deep blue cation 77 with strong acids. With water or alcohols it can be reconverted to the hydroxy or alkoxy compounds 76... 

The betaines 297 are easily prepared from a pyrylium salt and the appropriate 4-aminophenol followed by deprotonation. Typically, 2,4,6-triphenyl-pyridinium iodide and 4-aminophenol give the blue-black betaine (297 R = R = Ph, R = H) which also occurs as a red hexahydrate. With methyl iodide this compound gives 7V-(p-methoxyphenyl)-2,4,6-triphenyl-pyridinium iodide. 10,221... 

In the presence of H2O2 and LiBr l,l-dimethoxy-2,4,6-triphenyl-A5-phosphorin, (59) adds OH+ to position 4 and eliminates MeBr, giving the two cis-trans stereoisomers of 4-hydroxy-l-methoxy-2,4,6-triphenylphosphorin 1-oxide (60). Treatment with CF3C02H affords the stable delocalized deep blue cation (61) which again with water regenerates the two (separable) isomers (60). 

This catalyst3 is prepared in quantitative yield by refluxing 200 ml. of benzene solution containing 10 g. (0.046 mole) of anhydrous cobalt dibromide and 24.4 g. (0.092 mole) of triphenyl phosphine. A color change is observed, and the blue-green solid that precipitates on cooling to room temperature is filtered and dried. This catalyst, stored in a dry atmosphere, appears to be active indefinitely. 

Treatment of the conanine (372) with bromine-aqueous sodium carbonate yields192 (100%) the conenium salt (375) which is readily converted into (376) (80%). Compound (376) is also formed starting from (373). When C-20 is substituted by two methyl groups as in (374) the product is (377). The conanine (373) is photo-oxygenated,193 in the presence of methylene blue, to (376). The nitrone (378) is quantitatively deoxygenated by triphenyl phosphite with trimethyl phosphite the reaction is more complex.194... 

Since 2,4,6-triphenylphenol can be easily oxidized to a stable radical, we were interested in the behaviour of various substituted 2,4,6-triphenylbenzenes. When Schromm 140) oxidized 2,4,6-triphenyl-aniline by shaking a solution in benzene with lead dioxide, no radical was detected either by ESR spectroscopy or by trapping with tri-phenylmethyl. A red color (A. = 520 nm) possibly due to the ArNH radical was, however, observed.,40>. The addition of 70% perchloric acid changes the color to deep blue-violet. The compound was isolated when a benzene solution of 2,4,6-... 

Triphenyl Telluronium Acetonitrosolate 3.9 g (10 mmol) of triphenyl telluronium chloride are suspended in 50 ml of liquid ammonia in an apparatus suitable for work with liquid ammonia. To this suspension is added a solution of 1.9 g (10 mmol) of silver acetonitrosolate in 50 ml of liquid ammonia. The mixture is refluxed at the boiling point of liquid ammonia for 1 h, the ammonia is evaporated, and the residue is dried at 20° under high vacuum. 200 ml of methanol are added to the dry residue, the mixture is stirred for 30 min, silver chloride is filtered off, and the blue filtrate is evaporated to dryness. The residue is recrystallizcd from water and then from liquid anunonia yield 2.9 g (65%) m.p. 139° (dec.). 

In 1863 the same chemist prepared ethyl- and methyl-derivatives of rosaniline, and showed aniline blue to be triphenyl-rosaniline [13]. 

The arylation of 2,4,6-trisubstituted A -phosphorins with benzenediazonium tetrafluoroborates in methanol gives the trisubstituted 1-aryl-1-methoxy-X -phosphorin and a second product with aryl substitution in the 4-aryl group of the original phosphorin. Related investigations have been carried out using other benzenediazonium salts (0. Schaffer and Dimroth, Ber., 1975, 1Q8. 3271, 3281). 2,4,6-Triphenyl-or 4--benzyl-2,6-diphenyl-X -phosphorin reacts with diazoalkanes in the presence of protic nucleophiles to form 1-substituted 1--alkyl-2,4,6-triphenyl- or 1-substituted 1-alkyl-4-benzyl--2,6-diphenyl-X -phosophorin (P. Kieselack, C. Helland, and Dimroth, Ber., 1975, 108, 3656). 1-Methoxy-1-phenylphosphorins readily couple with benzenediazonium tetrafluoroborates in methanol-benzene to give blue to blue-violet disazo dyes (23) (Markl and R. Liebl, Synth., 1978, 846). 

Derivatives of triphenyl methane. This is the oldest class of which Nicholson s blue was the first exampk. Of comparatively simple structure is Xykne Blue VS (C.I. acid blue 1), formula (3) ... 

Mordant blue 29 Anionic Triphenyl methane 420 Guibal et al. (2003)... 

The zones or spots of separated compormds are generally visualized by detecting dehydrogenase activity with tetrazolium salt-based reagents. The metabolically active bacteria convert the tetrazolium salt into red formazan dye (2,3,5-triphenyl-2H-tetra-zolium chloride, tetrazolium red). A number of tetrezolium salts were evaluated as potential substrates for the enzymatic reaction, but p-iodonitrote-trazolium violet, tetranitro blue tetrazolium, and MTT were found to be suitable substrates. The equations below show the principle of the reaction with tetrazolium salt, 3-[4,5-dimethylthiazol-2-yl]-2,5 dip-henyltetrazolium bromide (MTT, tetrazolium dye). 

To enhance the applicability of UV spectrophotometry in pharmaceutical steroid analysis by increasing its selectivity and sensitivity, various methods have been developed based on chemical reactions leading to colored derivatives. Although their importance has decreased considerably, some of these methods are still in use in pharmacopoeias, mainly in the assay of formulations. For example, the A" -3-oxo and A " -3-oxo steroids can be determined as iso-nicotinoyl hydrazones (/Uax 380 and 410 nm 11500 and 17000, respectively). The dihydroxy-acetone side chain of corticosteroids at C17 reduces tetrazolium reagents to colored formazans (Amax 485 and 525 nm with triphenyl tetrazolium chloride and Tetrazolium Blue reagents, respectively e 16000 and 24000), thus creating the basis for a stability-indicating indirect colorimetric assay. Corticosteroids... 

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