Triphenylmethane derivatives

Among triphenylmethane derivatives, we ean mention Catechol violet or pyrocatechol violet  

Its properties are analogous to those of the preceding indicator. It is used for the 

It also possesses acid-base indicator properties. It can form complexes with metal cations even in acidic solution 3 pH 5. The free indicator in acidic solution exhibits a lemon yellow color. Its metal complexes are intensely red. It permits us to directly titrate Bi , Th +, Zn +, Pb +, and Co +. It is interesting to note that there are two imino-diacetic groups in its structure  

It functions in the pH range 0-12. Hence, it permits the titration of cations going from bismuth until alkaline earths (refer to the series of metallic ions that may be titrated by EDTA see preceding chapters). So a wide variety of bivalent metal ions may be titrated. In particular, this is the case for Hg for which few indicators are available. 

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For uniformity with the stmctures given in the Colourindex the ammonium radical (9) is used for the amino-substituted xanthenes and the keto form for the hydroxy derivatives. The xanthene dyes may be classified into two main groups diphenylmethane derivatives, called pyronines, and triphenylmethane derivatives (eg, (4)), which are mainly phthaleins made from phthaUc anhydride condensations. A third much smaller group of rosamines (9-phenylxanthenes) is prepared from substituted ben2aldehydes. The phthaleins may be further subdivided into the following fluoresceins (hydroxy-substituted) rhodamines (amino-substituted), eg, (6) and mixed hydroxy/amino-substituted. 

The triaryknethane dyes are broadly classified into the triphenyknethanes (Cl 42000—43875), diphenylnaphthyknethanes (Cl 44000—44100), and miscellaneous triphenylmethane derivatives (Cl 44500—44535). The triphenyknethanes are classified further on the basis of substitution in the aromatic nuclei, as follows (/) diamino derivatives of triphenylmethane, ie, dyes of the malachite green series (Cl 42000—42175) (2) triamino derivatives of triphenylmethane, ie, dyes of the fuchsine, rosaniline, or magenta series (Cl 42500—42800) (J) aminohydroxy derivatives of triphenylmethane (Cl 43500—43570) and (4) hydroxy derivatives of triphenylmethane, ie, dyes of the rosoHc acid series (Cl 43800—43875). Monoaminotriphenyknethanes are known but they are not included in the classification because they have Httie value as dyes. 

When the aldehyde is heated on the water-bath with 25 per cent, hydrochloric acid, it yields a triphenylmethane derivative, nonamethoxy-triphenylmethane, a body consisting of snow-white crystals, melting at 184 5°. The action of concentrated nitric acid upon the solution in glacial acetic acid of this triphenylmethane derivative gives rise to 1, 2, 5-trimethoxy-4-nitrobenzene (melting at 130°). With bromine, nonamethoxytriphenylmethane combines, with separation of a molecule of trimethoxy bromobenzene, into a tribromo additive compound of hexamethoxy diphenylmethane, a deep violet-blue body. The 1, 2, 5-tri-methoxy-4-bromobenzene (melting at 54 5°) may be obtained more readily from asaronic acid. 

The principle of forming the important inner salts of sulfonated triphenylmethane derivatives had thus been discovered. All of the commercially important products within this group are derived from phenylated rosaniline corresponding to the structure 121. 

A. The Basic Series.—In general, aromatic aldehydes condense with aromatic amines in the presence of zinc chloride to form triphenylmethane derivatives (0. Fischer) phenols and phenyl ethers behave similarly in the presence of concentrated sulphuric acid (Baeyer). The products formed are the leuco-compounds of well-known dyes. 

Phenolphthalein is a triphenylmethane derivative and can easily be connected with fuchsone, the parent substance of the dyes which belong to this series. Fuchsone is diphenylquinomethane and is obtained from p-hydroxytriphenylcarbinol by elimination of water (Bistrzycki) ... 

Triphenylmethane derivatives, rhodamines, and nitro derivatives of 9-dicyanomethylene fluorene are characterized by -type photoconductivity. 

A large number of useful dyes are substituted triphenylmethane derivatives. Crystal Violet (Section 28-4) and phenolphthalein (Exercise 28-28) are excellent examples of this kind of dye. 

Thus the phthaleins are triphenylmethane derivatives, being all derived from phthalophenone (diphenyl phthalide). 

Fig-1 Photochemical reactions responsible for photochromic behaviour in a) azobenzene derivatives, b) spiropyran compounds, c) fulgides, and d) triphenylmethane derivatives. 

Although picric acid is already a colouring matter, in general the colouring matters are more complicated compounds. Of the many thousands of colouring matters we shall only discuss the triphenylmethane derivatives further here. 

Pai et al. (1983) measured hole mobilities of a series of bis(diethylamino)-substituted triphenylmethane derivatives doped into a PC and poly(styrene) (PS). The mobilities varied by four orders of magnitude, while the field dependencies varied from linear to quadratic. In all materials, the field dependencies decreased with increasing temperature. The temperature dependencies were described by an Arrhenius relationship with activation energies that decrease with increasing field. Pai et al. described the transport process as a field-driven chain of oxidation-reduction reactions in which the rate of electron transfer is controlled by the molecular substituents of the hopping sites. 

According to their chemical structures and the Cl system, dyes can be classified into 17 groups nitro dyes, triphenylmethane derivatives, xanthenes, acridine derivatives, quinoline derivatives, azines, ant-hraquinones, indigoid dyes, phthalocyanines dyes, oxydation bases, insoluble azo dye precursors, and azo dyes (classes XII-XVII). In practice, dyes are classified into different application classes disperse, acid, basic, direct, vat, fiber-reactive, sulfur, preme-tallic, solvent dyes, and naphthols. 

These are used to color silk, wool, and other animal fibers, or nylon (polyamide) when high wet-fasmess is needed. Such dyes include monoazoic, diazoic, triphenylmethane, and anthraquinone compounds. Acid Yellow 23, Acid Black 48, Acid Black 63, and Acid Violet 17 (triphenylmethane derived Figure 16) were reported in the literature, mainly before 1985. Acid Yellow 61 (Supramine Yellow GW), Acid Red 359 (Neutrichrome Red SGN), and Acid Red 118 (Supramine Red GW), each tested in 5% petrolatum and removed after 3 days, were positive for skin... 

Crystal violet is another triphenylmethane derivative for which a tautomeric and pH-dependent equilibrium exists between the triphenylmethyl cation and its quinoidal form (Fig. 16). In acid medium, the quinoidal form leads to mono and dicationic forms by protonation on nitrogen atoms (Fig. 17). The pH range for Crystal violet is 0.0-1.8. UV spectrophotometry points out the three different forms (Fig. 18). 

Bromothymol blue (pH range 6.2-7.6) is a triphenylmethane derivative, the chemical structure and spectral behaviour of which are close to the ones of phenol red (Fig. 23). In basic medium, a strong bathochromic and hyperchromic effect can be noted (7 = 615 nm, e = 17800 Lmol-1 cm-1). The colour turns from yellow (X = 433 nm, e = 5900 Lmol-1 cm-1, pH = 5.0) to blue (pH = 12.0). The bromine atom located on the phenolic ring induces a more intense bathochromic shift than for Phenol red. 

Amyl nitrite Fuehsones from triphenylmethane derivatives s. 4, 270 CsHuOJVO,... 

Triphenylmethane derivatives can be converted into triphenylmethanol derivatives by various oxidizing agents. Triphenylmethane itself with nitric acid or with chromic acid in glacial acetic acid gives triphenylmethanol, and with lead tetraacetate gives triphenylmethyl acetate. The principal importance of this reaction lies in the technical synthesis of triphenylmethane dyes from their leuco bases, for which purpose very varied oxidants such as arsenic acid, nitrobenzene, nitrous acid, and nitrosylsulfuric acid are used. 

Such reactions, which will not be discussed further here, include the formation of diarylmethanes from an aldehyde and two molecules of an aromatic hydrocarbon, of triphenylmethane derivatives from an aldehyde and two molecules of an aromatic amine, and of phthaleins from phthalic anhydride and two molecules of phenol or resorcinol. 

Flavanones and Isoflavanones.- Reaction of the aryl benzyl ketone (120) with formaldehyde and dimethylamine has provided a new synthesis of isoflavanones in good yield.126 The same ketones can be cyclized to isoflavanones in good yield by treatment with di-iodomethane, a phase transfer catalyst (tetrabutylammonium iodide) and sodium thiosulphate.127 Flavanones react with hydroxylamine hydrochloride in ethanol-pyridine to give the oxime and not the oxazoline as previously claimed but when the oxime was heated with trifluoroacetic acid, the oxazoline was formed.128 The first triphenylmethane derivative to be found in nature, the flavanone melanervin (121), has been synthesized. Ammals (not animals, as printed in the abstract ) such as (122) have been applied to the... 

The xanthene dyes can be divided into two main groups viz. the biphenylmethane derivatives (pyronins) and the triphenylmethane derivatives (mainly the phthaleins). Among the phthaleins are fluorescein (hydroxy group) and rhodamin (amino group) and the dual compounds (hydroxy and amino). Both fluorescein and rhodamin, currently used as biological dyes, are also photosensitizers. 

Ramart-Lucas, P. Structure and absorption of colored triphenylmethane derivatives. Bull. Soc. Chim. 1945,12, 477-505 Chem. Abstr. 1946, 40, 22349. 

Loewe, S. Laxative activity of triphenylmethane derivatives. 1. Relationship between structure and activity of phenolphthalein congeners. J. Pharmacol. Exp. Ther. 1948, 94, 288-298. 

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