Triphenylmethane dyes malachite

Finally, two or three amino or dimethylamino groups in the /jara-position stabilize trityl cations so efficiently that the associated nonionized neutral compounds are no longer able to exist at all but heterolyze quantitatively to salts. These salts include, for example, the well-known triphenylmethane dyes malachite green and crystal violet ... 

Solvents 1—3 in Table 128 are suitable for separating bismarck-brown (C. I. 21000) and other basic azo dyes [61, 83]. The triphenylmethane dyes, malachite green (C. I. 42000) and methyl violet (C. I. 42535) have been separated with solvent 4 [62]. Fuchsine (C. I. 42510), rhodamine B (C. I. 45170) and rhodamine 6G (C. I. 45160) can be separated with solvent 5. Rhodamine B, malachite green, crystal dolet (C. I. 42555), methylene blue (C. I. 52015) and Victoria blue B (C. I. 44045) have been separated with solvent 7, using silica gel layers on microscope slides [49]. Many basic dyes of the xanthene class which are used for histological staining, e. g.. Acridine Red 3B (C. I. 45000), Pyronine G (C. I. 45005), rhodamine S (C. I. 45050), rhodamine G (C. I. 45150) and rhodamine B, can be separated with solvents 8—10 [78]. Numerous subsidiary conta-... 

The leuco-base of the triphenylmethane dye malachite green is oxidized by periodate to the dye-stuff very slowly at pH 4 in an acetate buffer. In the presence of manganese the oxidation proceeds rapidly, the manganese acting as a catalyst. The dye is slowly destroyed by a second reaction but after a suitable time interval extinctions at 6150 A are nearly proportional to the initial amount of manganese present in the sample. 

Many dyes and dye-related compounds belmig to the most recalcitrant and durable pollutants and due to their water solubility present the risk especially for the aquatic life. The anthraquinone dyes Alizarin Red and quinizarin, the triphenylmethane dye malachite green, and its reduced form leucomalachite green ° are oxidizable at BDD electrodes. 

DC11 Malachite Green, Basic Blue efficiency (95-98%) achieved within 6 h for 100 mM Acid Blue 25 (anthraquinone dye), 4 h for 55 mM Malachite Green (triphenylmethane dye), and 2 h for 750 mM Basic Blue X-GRRL under anaerobic conditions ... 

The technical preparation of crystal violet and of its methyl-free parent substance, parafuchsine, almost the oldest of the triphenylmethane dyes, is not so easily explained. As is well known, in this process aniline and p-toluidine are united by oxidation in an acid melt. (In the preparation of fuchsine itself, which contains a methyl group attached to one of the benzene rings, o-toluidine is an additional ingredient.) Although all the phases of this important synthesis have not yet been experimentally established, we may nevertheless explain it on the basis of a dehydrogenation similar to that involved in the formation of malachite green. Moreover, the union of several molecules of base proceeds exactly according to the principle on which indamines are formed (p. 321) (Bucherer). 

Nonchelating dyes include basic triphenylmethane dyes (e.g., Brilliant Green, Malachite Green, Crystal Violet), xanthene dyes (e.g., Rhodamine B, Rhodamine 6G), azine dyes (e.g., Methylene Blue), and acid dyes (e.g., Eosin, Erythrosin). These are intensely colored and when paired with an oppositely charged analyte ion lead to high sensitivities. 

Diphenylmethane and triphenylmethane dyes are monomethine dyes with two or three terminal aryl groups, of which at least one, but preferably two or three, are substituted by a donor group para to the methine carbon atom. The most important donor is the amino group. Important dyes belonging to this class include the well-known malachite green (12) [9] and crystal violet (13) [10], which are some of the oldest synthetic cationic dyes ... 

Triphenylmethane dyes are usually prepared in two steps 1) condensation of an N,N-dialkylaniline with a benzaldehyde compound and 2) oxidation of the resultant leuco base (27). The synthesis of C.I. Basic Green 4 (Malachite Green) is given as an example in Fig. 13.106. Alternatively, C.I. Acid Green 50 is prepared in three steps 1) condensation of... 

Rectification and photovoltaic effects in organic p-n junctions were first reported by Kearns and Calvin [101] and by Meier [3]. The combination of rhodamines or triphenylmethane dyes (both n-type) with merocyanines or phthalocyanines (both p-type) generated photovoltages up to 200 mV and photocurrents of about 10 8 A at low light intensity, with power conversion efficiency much less than 1%. More recent studies have been performed on merocyanine and malachite green [89,90] and on phthalocyanines and TPyP (a porphyrin derivative) [102,103]. These devices showed stronger spectral sensitization and better spectral match to a solar spectrum than those of Schottky barrier cells using only one component. 

As with DNA aptamers, there is a trend towards applying RNA aptamers to a particular application. Allosteric ribozyme sensors have been developed which are specific for caffeine and aspartame. " Using a fluorescence-based assay, caffeine or aspartame may be detected in solution over a 0.5 5mM concentration range. Aptamers designed to malachite green (151) or other triphenylmethane dyes have been developed that enhance the fluorescence of the dye up to 2300-fold. " A further fluorescence-based assay has been... 

Dyeing with a Triphenylmethane Dye—Crystal Violet or Malachite Green... 

Turnipseed, S.B. Roybal, J.E. Rupp, H.S. Hurlbut, J.A. Long, A.R. Particle-beam liquid-chromatography mass-spectrometry of triphenylmethane dyes—Application to confirmation of malachite green in incurred catfish tissue. J. Chromatogr. 1995, 670, 55-62. 

Crystal violet (Gentian violet), brilliant green and malachite green are triphenylmethane dyes widely used to stain bacteria for microscopic examination. They have bacteriostatic and fungistatic activity and have been applied topically for the treatment of infections. Due to concern about possible carcinogenicity, they are now rarely used. 

The first antifungal agents included a number of early triphenylmethane dyes, such as malachite green, gentian violet and basic fuchsin (see Chapter 1). Tolfanate (129), an iV-alkylated m-toluidine derivative, is a topical antifungal agent77. 

The triphenylmethane dyes. The most important representatives of this group of compounds are crystal violet, methyl violet 6B, methyl green, malachite green, and gentian violet. 

Spectrophotometric methods based on ion associates with basic dyes are very sensitive. The Co-thiocyanate complex was associated with Malachite Green (CCI4 -i- cyclohexane), (e = 8.6-10 ) [61], Turquoise Blue (triphenylmethane dye) (toluene -1- DMF) [62], and 6-nitrodimethyline-carbocyanine [63,64]. The anionic complex of Co with chloro-oxine [65] associated with Rhodamine 6G was extracted with benzene. The complex of Co with 2-nitroso-l-hydroxynaphthalene-4-sulphonic acid was extracted into CHCI3 as the associate with a basic azo dye (e = 1.66-10 at 566 nm) [66]. 

The bromide complex of indium gives extractable ion-associates with the xanthene basic dyes Rhodamine B [49] and triphenylmethane dyes. Brilliant Green [50,51], and Crystal Violet [52], extractable into non-polar solvents. The related dye. Malachite Green, has been used to form an associate with tetra-iodoindate, extractable with benzene, hexane, and CCI4 [53]. 

A concentration cell has been described which is based upon the ionic photodissociation of the leucocyanides of the triphenylmethane dyes crystal violet or malachite green in acetonitrile or alcohol, as in reaction (4).28 This reaction is... 

S. Schneidei G. Brehm, and P. Freunscht, Comparison of Surface-Enhanced Raman and Hyper-Raman Spectra of the Triphenylmethane Dyes Crystal Violet and Malachite Green, Physica Status Solidi B-Basic Research 189, 37 (1995)... 

In fact, the earliest application of kinetic methods was to determine trace levels of substances exerting catalytic activity in oxidation-reduction reactions involving multiple electron transfers (1885-trace level V on its catalysis of the oxidation of aniline). For example, the reduced form of many triphenylmethane dyes is colorless , and loses two electrons on oxidation to the dye. The rate of reaction with such oxidants as 104 is relatively slow, but can be catalyzed by trace levels of transition metal ions which involve single electron transfer in their own redox steps. Thus, trace levels of manganese can be determined by the proportionality of the rate of oxidation of leuco-malachite green by iodate at less than micromolar concentrations. Similarly, trace levels of Cu ", < 10 M, can be determined from the catalytic effect on the atmospheric oxidation of ascorbic acid. Such systems can be written as a generalized redox reaction... 

Production of N,N-dimethylaniline in Western Europe in 1985 was around 9,0001. Among the most important compounds based on N,N-dimethylaniline is Michler s ketone, which is used to manufacture triphenylmethane dyes such as Basic Violet 3 (Crystal Violet) or Basic Green 4 (Malachite Green), which is obtainable by reaction with benzaldehyde in a sulfuric acid medium, followed by oxidation. 

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