Triarylmethanes

ANHBIOHCS - BETA-LACTAMS - PENICILLINS AND OTHERS] (Vol 3) Assaying triarylmethane dyes... 

A useful classification of sensitizing dyes is the one adopted to describe patents in image technology. In Table 1, the Image Technology Patent Information System (ITPAIS), dye classes and representative patent citations from the ITPAIS file are Hsted as a function of significant dye class. From these citations it is clear that preferred sensitizers for silver haUdes are polymethine dyes (cyanine, merocyanine, etc), whereas other semiconductors have more evenly distributed citations. Zinc oxide, for example, is frequendy sensitized by xanthene dyes (qv) or triarylmethane dyes (see Triphenylmethane and related dyes) as well as cyanines and merocyanines (see Cyanine dyes). 

The hexoses that are the initial products of acid hydrolysis of sucrose (1) react at el vated temperature under the influence of acids to yield furfural derivatives (2). Thed condense, for example, with the phenols to yield triarylmethanes (3), these react furthei by oxidizing to yield colored quinoid derivatives (2, 4). Polyhydric phenols, e. g. resorj cinol, on the other hand, yield condensation products of Types 5 and 6 [2],... 

Dyes. Vital dyes have been used for many years in a variety of clinical situations. Patent blue V (also called E131, Acid blue 3, Disulfine blue) and Isosulfan blue (also called Patent blue violet or Lymphazurine), belong to the group of triarylmethane dyes and are the most commonly used [24]. Reports of IgE-dependent anaphylaxis arise. Anaphylactic reactions involving methylene blue seems to be very rare, however, several reports of sensitization to both Patent blue and methylene blue have previously been reported. 

Azo dyes Allura Red AC, Amaranth, Azorubine, Brilliant Black BN, Brown FK, Brown HT, Lithol Rubine BK, Ponceau 4R, Red 2G, Sunset Yellow, Tartrazine Triarylmethane (triphenylmethane) dyes Brilliant Blue FCF, Fast green FCF, Green S, Patent Blue V... 

Briliant Blue FCF (E 133, FD C Blue No. 1, Cl Food Blue 2) is a triarylmethane dye disodium 3-[N-ethyl-N-[4-[[4-[N-ethyl-N-(3-sulfonatobenzyl)-amino] phenyl] (2-sulfonatophenyl)methylene]-2,5-cyclohexadiene-l-ylidene]ammoniome-thyl] benzenesulfonate (or disodium (4-(N-ethyl-3-sulfonato-benzylamino) phenyl)-a-(4-N-ethyl-3-sulfonatobenzylamino)cyclohexa-2,5-dienylidene)-toluene-2-sul-... 

Fast Green FCF (FD C Green No. 3, Cl Food Green 3) is a triarylmethane dye related to Brilliant Blue, the disodinm 3-[N-ethyl-N-[4-[[4-[N-ethyl-N-(3-snl-fonatobenzyl)amino] -phenyl] (4-hydroxy-2-snlfonatophenyl)methylene] -2,5-cyclo-hexadien-l-ylidene]ammonio-methyl]-benzenesnlfonate. Fast green is a red to brown-violet powder or crystals, solnble in water, sparingly solnble in ethanol, with a maximnm absorption in water at 625 nm. It is not permitted as food colorant in the EU. -"... 

Green S (E 142, Cl Food Green 4, Brilliant Green BS) is a triarylmethane dye, with the chemical name sodinm N-[4-[[4-(dimethylamino)phenyl](2-hydroxy-3,6-disnlfo-l-naphthalenyl)-methylene]-2,5-cyclohexadien-l-ylidene]-N-methylmetha-naminium. The calcium and potassinm salts are also permitted. Green S is a dark bine or green powder or grannies, solnble in water, slightly solnble in ethanol, with a maximum absorption in water at 632 nm = 1720). It is not permitted as a... 

Patent Blue V (E 131, Cl Food Blue 5, Patent Blue 5) is a triarylmethane dye, the calcium or sodium salt of 2-[(4-diethylaminophenyl)(4-diethylimino-2,5-cyclo-hexadien-l-ylidene)methyl]-4-hydroxy-l,5-benzenedisulfonate. It is a dark-blue powder, soluble in water, slightly soluble in ethanol. The absorption maximum is 638 nm in water, pH 5, with = 2000. Patent blue is not permitted for use as... 

Benzoyl leuco Methylene Blue (1), which is a phenothiazine leuco dye, has been known since 1900. The material was developed to extend the range of hues and colors obtainable in such applications as pressure-sensitive carbonless paper and to complement other classes of leuco dyes such as triarylmethanes, crystal violet lactone, and fluorans. Benzoyl leuco Basic Blue 3 (2), which is a phenoxazine leuco dye, is a more recent development. 

The possibility of replacing all three phenyl rings in the triarylmethane lactone structure by heterocycles has also been exploited. The first compound to be described83 was the 3,3-bisindolyl-7-azaphthalide (18). This... 

Introduction of an ethylene bridge between the maso-carbon atom and one of the diaminophenyl groups of a triarylmethane-type phthalide results in a considerable bathochromic shift, thus producing color formers exhibiting absorption in the near infrared region of the electromagnetic spectrum. 

Fusion of the two arylamino groups of a triarylmethane phthalide color former results in the formation of spirofluorene phthalides. Due to the increased planarity of this system, a bathochromic shift results leading also to color formers showing infrared absorption when developed. This was first exemplified in 1983102 by preparation of phthalide 26 as shown in Scheme... 

One further example of this principle of bridging the aryl groups of a triarylmethane phthalide was reported in 1986.108 Thus, treatment of phthalide 27 with aluminum chloride results in the formation of the spirobenzanthracene 28 as shown in Scheme 11. These color formers also exhibit absorption in the near infrared spectral region, but no further reports of such compounds have since been published. 

Arylmethane leuco dyes are converted into di- or triarylmethane dyes on oxidation. This class of dye precursors sometimes is referred to as leuco di- or triphenylmethane dyes, or di- or triphenylmethane leuco dyes. The use of the term di- or triarylmethane dyes can be misleading as the central carbon atom is a carbonium ion. Instead, the term di- and triarylmethine dye is recommended for this class as it correlates with the well-known polymethine dyes. Nevertheless, it has not been commonly used. 

In general, the triarylmethane leuco skeleton can be represented by structures 1-4. Traditional leuco di- and triphenylmethane dyes frequently include compounds of type 1 and 3. The closely related compounds 2 and 4 are derived from 1 and 3. Another closely related type is the lactone or phthalide 5 (see Chapter 4). In all of these leuco dyes, one or more of the phenyl rings can be replaced by a hetaryl ring or by a fused aromatic ring such as a naphthalene. 

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