Thiazine blue

Strictly, the name Thiazine blue refers to the chloride. Chloride [2391-29-9]. 

Ethylrhodamine B, in R-00002 Thiazine blue Chloride, in T-00136 Diethylammonium diethyldithiocarbamate, in D-00344... 

Methylene Blue [61-73-4] CI Basic Blue 9 (CI 52015), (26), is the classic thiazine dye still in use today. This dye was first reported in 1876 (1). 

Synthesis. The method of synthesis for Methylene Blue described in reference 14 is stiU the stepwise method of choice for thiazine dyes. /V,/V-Dimethy1-y-pheny1ene diamine [99-98-9], CgH22N2, reacts with sodium thiosulfate [7772-98-7] to form the thiosulfonic acid which condenses with /V, /V-dimetby1 ani1 ine [121 -69-7], CgH N, in the presence of sodium dichromate [10588-01-9] to the indamine, then with copper sulfate [18939-61 -2] and sodium dichromate to Methylene Blue (26). 

When Methylene Blue is reduced, the yellowish leuco cannot be isolated due to instant air oxidation. Benzoylation of the leuco form provides stabilization. There are also leuco thiazine dyes stable enough to be isolated without the need for aroylation. 

There are cationic thiazine dyes (3 to 5) and neutral thiazinone dyes exemplified by Methylene Violet (6). Like leuco Methylene Blue, leuco Methylene Violet is too air sensitive to be isolated and therefore requires acylation. 

Phenazine leucos are capable of providing yellow, orange, red, and magenta images whereas thiazine and oxazine leucos are normally restricted to turquoise, blue, and purple colors.19 Color depends on the electronic nature of substituents R1 to R4, as shown in Table 3. 

HPLC-UV-Vis-ESI MS was used to identify indigoid dyes in blue fibre extracts taken from a Japanese tapestry (nineteenth century). Two main colourants were recognized as indigotin and Methylene Blue, [44] a thiazine cationic dye first synthesized at the end of the nineteenth century, commonly used for silk and cotton dying (Figure 13.9). 

The decolorization potential of immobilized P. chrysosporium MTCC 787 for azo dyes Acid Orange, Acid Red 114, triphenylmethane dye Methyl Violet, diazoic dye Congo Red, vat dye Vat Magenta, thiazine dye Methylene Blue, and anthraqui-none Acid Green was demonstrated by Radha et al. [53]. Decolorization experiments were carried out with immobilized calcium alginate (Ca-ALG) beads of different sizes (2-6 mm). 

The delocalised charged dyes are dominated by cyanine dyes, exemplified by the azacarbocyanine Cl Basic Yellow 11 (2.27), the diazacarbocyanine Cl Basic Yellow 28 (2.30) and the diazahemicyanine Cl Basic Blue 41 (2.49). Where necessary quatemisation is carried out as a post colour forming reaction. Other structural types include oxazines, thiazines and triphenyhnethane dyes. 

Three absorption bands are found in the UV spectra of 6//-l,3-thiazine-6-thiones 33 and 34. The spectrum of the 2-phenyl derivative contains bands at A ax = 253, 314, and 425 nm. A blue shift is seen when the 2-phenyl substituent is replaced by the dimethylamino group and the bands are observed at Aniax= 240.5, 288, and 428 nm <1997S573>. 

Thus, the presence of a thiamine ring in Cl Sulfur Blue 9 was conclusively proved. The thiazine ring is the fundamental chromophore that accounts for the high color value of both the sulfur dye and Methylene Blue [61-73 1-], including their ability to form pale yellow leuco forms on reduction. Methylene Violet (IS) is obtained from Methylene Blue (16) by hydrolysis in boiling alkali... 

On more severe thionation, a third thiazine ring is formed to give a sulfur black. However, if hydroxyl groups instead of amino groups are attached at positions 2 and 2, no ring closure would take place and the blue dye would be stable to heat. These formulas are general expressions for the nuclear structures of the blue-to-black sulfur dyes they do not take into consideration the quinonoid formation of each dye and other aspects. 

Immedial Pure Blue (25) forms a crystalline complex with sodium bisulfite and the thiazine ring structure has been clearly established (48AG141). The compound is isosteric with a number of vat dyes, e.g. indanthrone, and thus its hue and good affinity for cellulosic fibres might reasonably be expected. 

Many complex dye molecules form triplet states which undergo facile reduction. Thiazine dyes such as thionine, 49, and methylene blue are photoreduced by a variety of oxidizing agents, including ferrous ion.475... 

Blue dyes are derived from anthraquinone, phthalocyanine, or metallized formazan. See also Anthraquinone (Figs. I and 2). There are also oxazine and thiazine dyes reported (Fig. 2). 

MB belongs to the group of thiazine dyes and is widely used as a redox indicator in analytical chemistry and as a staining dye in biology. In aqueous solutions, which are intensely blue due to the strong light absorbance, MB forms monomers and dimers. The reduced form of MB, called Leuco Methylene blue (LMB), is colorless. 

As can be seen from Table 9.12, photochromism is also strongly affected by humidity. It is well known that thiazine and its derivatives undergo photoreduction smoothly in the presence of such activated surfaces as silica gel and alumina with water molecules,37 and that methylene blue is also photochemically reduced in acid solution, even with only available water as the reducing agent38 Therefore the water present in polymer films must produce a thionine-water hydration system, which accelerates the rate of the photoreduction of thionine, as well as promoting the contact of reductants by a plasticizer effect. PVA, used as the matrix, can also play the role of reductant, but its extent may be minor as compared with the added reductant. The effect of water is supported by the fact that a less hydrophilic polymer matrix such as poly(methyl methacrylate) does not exhibit photochromism even though the system contains an appreciable amount of reductants. 

OXAZINE AND THIAZINE DYES Methylene Blue from Dimethylaniline... 

Heinecken et found that a series of quinoneiminoid pheno-thiazine dyes, like methylene blue and its analogs, give ESR signals in sulfuric acid, the four lines of which have relative intensities 1 2 2 1. In alkaline solutions the spectrum consists of a 1 1 1 triplet. In both cases high resolutions were achieved with solutions in... 

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