Triarylmethane derivatives

Sulfur-containing triarylmethane derivatives XIXa,b react with oxygen in sunlight to yield the peroxides of XXa,b.246,247 The formation of XX may be explained in either way ... 

Phthaleins. Dyes of this class are usually considered to be triarylmethane derivatives. Phenolphthalein [77-09-8] (23, R = CO) and phenol red [143-74-8] (23, R = S02) are used extensively as indicators in colorimetric and titrimetric determinations (see Hydrogen-ion activity). These compounds are prepared by the condensation of phenol with phthalic anhydride or o-sulfobenzoic anhydride, respectively, in the presence of a dehydrating agent. 

A number of papers concerning the formation of carbocations by photolysis of mono-, di-, and triarylmethane derivatives have been... 

Shi et al. [161-164] studied a different reaction of an array of triphenylmethane and triarylmethane derivatives such as alkanes, alkenes, alkynes, phosphonates, phosphonic acids and esters, dialkylamines, triaryl acetic acid, triaryl acetonitriles, triaryl acetates, and tetraarylmethanes and published a review of their work [65]. Mainly from product studies they proposed the special case of di-Jt-methane and oxa-di-7u-methane reactions [165], viz. a,a-elimination gives a biaryl and the corresponding carbenes and operates in polar and nonpolar sol-... 

In this reaction, usually carried out in an acid medium (H2SO4, HCl), di- or triarylmethane derivatives are formed which are intensely colored (seep. 47). Pomeroy and Pollard (7) investigated 11 phenolic compotmds and their... 

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],... 

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. 

Use of benzotriazole in the preparation of diphenylmethanes and triphenylmethanes has been reviewed." Benzotriazole is condensed with an aldehyde and then allowed to react with naphthols to form a diphenyl-methane benzotriazole derivative such as 69 (Scheme 9). The benzotriazole moiety in 69 is displaced by a Grignard reagent to give triphenylmethanes.79 100 This method allows for the preparation of triarylmethanes which contain three different aromatic rings. Compounds 70-72 are prepared by this method. 

The presence of at least two sulphonic acid groups in the triarylmethane ring system permits the derivatives to be applied as acid dyes. Although sulphonic acid groups are often present in the intermediates used, acid dyes can also be obtained by direct sulphonation of the basic dye itself or at the leuco stage. 

The incorporation of an indole ring system often leads to an improvement in the light fastness. A suitable example is Cl Acid Blue 123 (6.177), which is derived from 4,4 -dichlorobenzophenone. Condensation with l-methyl-2-phenylindole in the presence of phosphorus oxychloride produces the triarylmethane ring system. Replacement of the chlorine atoms with p-phenetidine, followed by sulphonation, gives the dye. 

Several examples of typical triarylmethane dyes have already been mentioned, in particular, pararosaniline (6.161), malachite green (6.162) its o-chloro derivative (6.169), crystal violet (6.164), rosaniline (6.165) and diphenylamine blue (6.173). Cl Basic Green 1 (6.168 R = C2H5), the ethyl analogue of malachite green, is prepared by the aldehyde route and is isolated as the sulphate. The ethyl analogue of crystal violet is Cl Basic Violet 4 (6.167 R = C2H5) and is obtained by the ketone route. 

Triarylmethane compounds also dissociate into ions (Scheme 9) giving cationic dyes which are stabilized by resonance. Many derivatives of Malachite Green (129) have been made including examples where the unsubstituted phenyl group has been replaced by a pyridyl (130) or furyl (131) group (B-57MI11400). 

The triarylmethane dyes are broadly classified into the triphenyl-methanes (Cl 42000-43875), diphenylnaphthylmethanes (Cl 44000-44100), and miscellaneous triphenylmethane derivatives (Cl 44500-44535). The triphenylmethanes are classified further on the basis of substitution in the aromatic nuclei, as follows (1) diamino derivatives of triph-enyhnetliane, i.e., dyes of the malachite green series (Cl 42000-42175) (2) triamino derivatives of triphenylmethane, i.e., dyes of the fuchsine, rosani-line. or magenta series (Cl 42500-42800) (3) aminohydroxy derivatives of triphenylmethane (Cl 43500-43570) and (4) hydroxy derivatives of triphenylmethane, i.e., dyes of the rosolic acid series (Cl 43800-43875). Monoaminotriphcnylmcthancs arc known but they arc not included in the classification because they have little value as dyes. 

Heteroarylmethane Dyes. Dyes of this class usually have either one or two lieteroaiyl groups attached to die methane carbon atom. Trihetarylmediane dyes are known and have been investigated for their pharmacological activity as well as their color characteristics. These types of triarylmethane dyes and their derivatives are used as color formers in thermoreactive and pressure-sensitive recording materials. 

Triarylmethane Dyes with Near-Infrared Absorption. The long wavelength absorption bands of triarylmethane dyes can be shifted into the near-infrared region, but the dyes still remain colored because other absorption bands are shifted to or stay in the visible region. These types of triarylmediane dyes and their derivatives have been claimed as infrared absorbers for optical information recording media and security devices, and as organic photoconductors for nse in lithographic plate production. 

Triarylmethane dyes are derivatives of triphenylmethane and diphenylnaphthylmethane. The presence of one or more primary, secondary, or tertiary amino or -OH groups in the para position to the methane carbon determines the dye color. Halogen, carboxyl, or sulfonic acid substituents also may be present on the aromatic rings. Triarylmethane colorant applications include basic, acid, solvent, and mordant dyes. Major uses are in printing inks. 

The history of the discovery of the dye Malachite Green in the mid-1870s, followed by its structural elucidation as a trityl derivative, was reviewed.51 Cationic triarylmethane dyes containing one, two, or three naphthalenes [e.g. (16)] were prepared, and their... 

The current organic photoreceptors are triarylamines, triarylmethanes, hy-drazones, oxadiazoles, pyrazolines, oxazoles, and more recently, stilbene derivatives. The polymer matrix, on the other hand, is constituted by polyesters and polycarbonates (Fig. 5). The common presence of aromatic amines as substituents in all these materials contributes to efficient hole transport [44]. The nonbonding electron pair on the nitrogen atom, in fact, confers on these molecules a low oxidation potential, and consequently, the production of a chemically stable radical cation with the possibility of an effective overlap of nonbonding molecular orbitals between neighboring molecules. 

The oxidation of the methyl group in toluene derivatives to the aldehyde is an important stage in triarylmethane dye manufacture, p- toluene sul-fonyl chloride is first hydrolyzed in concentrated sulfuric acid and then subjected to the oxidizing action of a manganese compound to produce benzaldehyde-4-sulfonic acid [11]. 

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