The Structure of the So-Called Toluidine Blue

Abstract

Toluidine Blue is a dye that has certain rather unique properties, in particular, its spectral absorption characteristics, which do not resemble those of ordinary blue dyes (Fig. 1). While it has long been available on the market, its structure has never been divulged. It is not listed in Schultz (1) or the Colour Index (2), presumably because it is not important in the dyeing of textiles.1 In connection with other work on color and constitution being carried out in this laboratory, it became of interest to learn the structure of this dye.From the results of elementary analyses of the purified, salt-free dye, it was possible to write an empirical formula, C2 sH2 0N2Na2010S2. Qualitative reactions for classification indicated that it was an acid anthraquinone dye.

Investigation of Diffusion Characteristics through Microfluidic Channels for Passive Drug Delivery Applications

“…Full UV spectra of both RB and TB were shown to have peaks similar to those reported in the literature [ 28 , 29 ]. Rhodamine B was found to have a peak at 550 nm, where TB has two peaks in the 600 region (596 nm and 640 nm).…”

“…After devices were filled, they were placed in a sealed plastic centrifuge tube with 4 mL of (PBS) and placed in a Series 2 Water Jacketed Incubator (Thermo Scientific) at 37°C to simulate the vitreous humor of the eye. Absorbance values of the solution of PBS and dye for each device were measured using Genesys 10S UV-Vis Spectrophotometer (Thermo Scientific) every 24 hours at 550 nm [ 28 ] and 640 nm [ 29 ] for Rhodamine B (RB) and Toluidine Blue (TB), respectively. The device was taken out of the centrifuge tube and the liquid was mixed in a vortex mixer before each measurement.…”

Some Observations Upon the Relation Between Absorption Spectra and Constitution of Certain Acid Anthraquinone Dyes

“…An inspection of these curves reveals the great differences between the 1,4-and 1.5series; thus, the differences between the second and third peaks in the green 1 This dye may not be strictly comparable, for it appears to have four bands in the ultraviolet with a suggestion of a fifth at about 384 µ. The band head at 330 has been assumed to be comparable to the third band in the other dyes, and the values in Table II series in the ultraviolet is more than double that in the blue series (125 vs. 35-55), the third peak in the former appearing in the visible.…”

“…The isomers and homologs are derived by varying the nature of the groups in the rings A, B, and C. The older dyes considered (the formulas of which are not given in this paper) are the sodium salts of 1,5-di(2,-sulfo-4'-methylanilino)anthraquinone (Anthraquinone Violet) (4), 1.4di-(2'-sulfo-4'-methylanilino)anthraquinone (Alizarin Cyanine Green) (5), 1.4-di-(3'-sulfo-4,-methylanilino)anthraquinone (Alizarin Direct Green) (6), 7,8-dihydroxy-1,4-di-(2,-sulfo-4'-methylanilino)anthraquinone (Alizarin Viridin) (7), and l-amino-2-bromo-4-(2'-sulfo-4'-methylanilino)anthraquinone (Alizarin Pure Blue B) (8). Toluidine Blue is the sodium salt of 1,5-di-(2'-sulfo-4'-methylanilino)-4,8-dihydroxyanthraquinone, and Toluidine Green is the 1.4-isomer (1).…”

New Poly(arylene ethynylene)s Consisting of Electron‐Deficient Aryleneimide Units

“…The compounds 3,6-dibromophthalic anhydride [13] and diethyl-2,5-dibromoterephthalate [14] were synthesized according to literature methods. The compound 2,5-diethynylpyridine [15] was prepared by modifying a reported method.…”